SMART ARM-based Microcontrollers

AT13526: ASF Manual (SAM C21)

APPLICATION NOTE

Preface

The Atmel® Software Framework (ASF) is a collection of free embeddedsoftware for Atmel microcontroller devices. It simplifies the usage of Atmelproducts, providing an abstraction to the hardware and high-value middle-ware. ASF is designed to be used for evaluation, prototyping, design, andproduction phases. ASF is integrated in the Atmel Studio IDE with agraphical user interface or available as a standalone package for severalcommercial and open source compilers. This document describes the APIinterfaces to the low level ASF module drivers of the device.

For more information on ASF, refer to the online documentation at http://www.atmel.com/asf.

Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

http://www.atmel.com/asfhttp://www.atmel.com/asf

Table of Contents

Preface............................................................................................................................ 1

1. Software License..................................................................................................... 19

2. SAM Analog Comparator (AC) Driver......................................................................202.1. Prerequisites...............................................................................................................................202.2. Module Overview........................................................................................................................20

2.2.1. Driver Feature Macro Definition...................................................................................212.2.2. Window Comparators and Comparator Pairs.............................................................. 212.2.3. Positive and Negative Input MUXes............................................................................ 212.2.4. Output Filtering............................................................................................................ 212.2.5. Input Hysteresis........................................................................................................... 212.2.6. Single Shot and Continuous Sampling Modes............................................................ 222.2.7. Events..........................................................................................................................222.2.8. Physical Connection.................................................................................................... 22

2.3. Special Considerations...............................................................................................................232.4. Extra Information........................................................................................................................ 232.5. Examples....................................................................................................................................232.6. API Overview..............................................................................................................................24

2.6.1. Variable and Type Definitions...................................................................................... 242.6.2. Structure Definitions.................................................................................................... 242.6.3. Macro Definitions......................................................................................................... 262.6.4. Function Definitions..................................................................................................... 272.6.5. Enumeration Definitions...............................................................................................36

2.7. Extra Information for AC Driver.................................................................................................. 402.7.1. Acronyms.....................................................................................................................402.7.2. Dependencies..............................................................................................................402.7.3. Errata........................................................................................................................... 402.7.4. Module History.............................................................................................................40

2.8. Examples for AC Driver..............................................................................................................402.8.1. Quick Start Guide for AC - Basic................................................................................. 402.8.2. Quick Start Guide for AC - Callback............................................................................ 44

3. SAM Analog-to-Digital Converter (ADC) Driver.......................................................493.1. Prerequisites...............................................................................................................................493.2. Module Overview........................................................................................................................49

3.2.1. Sample Clock Prescaler.............................................................................................. 503.2.2. ADC Resolution........................................................................................................... 503.2.3. Conversion Modes.......................................................................................................503.2.4. Differential and Single-ended Conversion................................................................... 503.2.5. Sample Time................................................................................................................513.2.6. Averaging.....................................................................................................................513.2.7. Offset and Gain Correction.......................................................................................... 523.2.8. Pin Scan...................................................................................................................... 523.2.9. Window Monitor........................................................................................................... 52

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

2

3.2.10. Events..........................................................................................................................523.3. Special Considerations...............................................................................................................533.4. Extra Information........................................................................................................................ 533.5. Examples....................................................................................................................................533.6. API Overview..............................................................................................................................53

3.6.1. Variable and Type Definitions...................................................................................... 533.6.2. Structure Definitions.................................................................................................... 543.6.3. Macro Definitions......................................................................................................... 563.6.4. Function Definitions..................................................................................................... 573.6.5. Enumeration Definitions...............................................................................................68

3.7. Extra Information for ADC Driver................................................................................................733.7.1. Acronyms.....................................................................................................................733.7.2. Dependencies..............................................................................................................733.7.3. Errata........................................................................................................................... 743.7.4. Module History.............................................................................................................74

3.8. Examples for ADC Driver........................................................................................................... 743.8.1. Quick Start Guide for ADC - Basic...............................................................................743.8.2. Quick Start Guide for ADC - Callback..........................................................................763.8.3. Quick Start Guide for Using DMA with ADC/DAC....................................................... 80

4. SAM Brown Out Detector (BOD) Driver...................................................................874.1. Prerequisites...............................................................................................................................874.2. Module Overview........................................................................................................................874.3. Special Considerations...............................................................................................................874.4. Extra Information........................................................................................................................ 874.5. Examples....................................................................................................................................884.6. API Overview..............................................................................................................................88

4.6.1. Structure Definitions.................................................................................................... 884.6.2. Function Definitions..................................................................................................... 884.6.3. Enumeration Definitions...............................................................................................90

4.7. Extra Information for BOD Driver................................................................................................924.7.1. Acronyms.....................................................................................................................924.7.2. Dependencies..............................................................................................................924.7.3. Errata........................................................................................................................... 924.7.4. Module History.............................................................................................................92

4.8. Examples for BOD Driver........................................................................................................... 924.8.1. Quick Start Guide for BOD - Basic.............................................................................. 924.8.2. Application Use Case for BOD - Application................................................................94

5. SAM Configurable Custom Logic (CCL) Driver....................................................... 955.1. Prerequisites...............................................................................................................................955.2. Module Overview........................................................................................................................955.3. Special Considerations...............................................................................................................955.4. Extra Information........................................................................................................................ 955.5. Examples....................................................................................................................................965.6. API Overview..............................................................................................................................96

5.6.1. Structure Definitions.................................................................................................... 965.6.2. Function Definitions..................................................................................................... 975.6.3. Enumeration Definitions...............................................................................................99

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

3

5.7. Extra Information for CCL Driver.............................................................................................. 1015.7.1. Acronyms...................................................................................................................1015.7.2. Dependencies............................................................................................................1015.7.3. Errata......................................................................................................................... 1015.7.4. Module History...........................................................................................................101

5.8. Examples for CCL Driver..........................................................................................................1015.8.1. Quick Start Guide for CCL - Basic............................................................................. 102

6. SAM Digital-to-Analog (DAC) Driver......................................................................1066.1. Prerequisites.............................................................................................................................1066.2. Module Overview......................................................................................................................106

6.2.1. Conversion Range..................................................................................................... 1076.2.2. Conversion.................................................................................................................1076.2.3. Analog Output............................................................................................................1076.2.4. Events........................................................................................................................1086.2.5. Left and Right Adjusted Values..................................................................................1086.2.6. Clock Sources............................................................................................................108

6.3. Special Considerations.............................................................................................................1096.3.1. Output Driver............................................................................................................. 1096.3.2. Conversion Time........................................................................................................109

6.4. Extra Information...................................................................................................................... 1096.5. Examples..................................................................................................................................1096.6. API Overview............................................................................................................................109

6.6.1. Variable and Type Definitions.................................................................................... 1096.6.2. Structure Definitions.................................................................................................. 1096.6.3. Macro Definitions....................................................................................................... 1106.6.4. Function Definitions....................................................................................................1116.6.5. Enumeration Definitions.............................................................................................122

6.7. Extra Information for DAC Driver..............................................................................................1236.7.1. Acronyms...................................................................................................................1236.7.2. Dependencies............................................................................................................1246.7.3. Errata......................................................................................................................... 1246.7.4. Module History...........................................................................................................124

6.8. Examples for DAC Driver......................................................................................................... 1246.8.1. Quick Start Guide for DAC - Basic.............................................................................1246.8.2. Quick Start Guide for DAC - Callback........................................................................127

7. SAM Direct Memory Access Controller (DMAC) Driver.........................................1337.1. Prerequisites.............................................................................................................................1337.2. Module Overview......................................................................................................................133

7.2.1. Driver Feature Macro Definition.................................................................................1357.2.2. Terminology Used in DMAC Transfers.......................................................................1357.2.3. DMA Channels...........................................................................................................1357.2.4. DMA Triggers.............................................................................................................1357.2.5. DMA Transfer Descriptor........................................................................................... 1357.2.6. DMA Interrupts/Events...............................................................................................136

7.3. Special Considerations.............................................................................................................1367.4. Extra Information...................................................................................................................... 1367.5. Examples..................................................................................................................................136

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

4

7.6. API Overview............................................................................................................................1367.6.1. Variable and Type Definitions.................................................................................... 1367.6.2. Structure Definitions.................................................................................................. 1377.6.3. Macro Definitions....................................................................................................... 1397.6.4. Function Definitions................................................................................................... 1397.6.5. Enumeration Definitions.............................................................................................146

7.7. Extra Information for DMAC Driver...........................................................................................1497.7.1. Acronyms...................................................................................................................1497.7.2. Dependencies............................................................................................................1497.7.3. Errata......................................................................................................................... 1497.7.4. Module History...........................................................................................................149

7.8. Examples for DMAC Driver...................................................................................................... 1507.8.1. Quick Start Guide for Memory to Memory Data Transfer Using DMAC.....................150

8. SAM Divide and Square Root Accelerator (DIVAS) Driver.................................... 1548.1. Prerequisites.............................................................................................................................1548.2. Module Overview......................................................................................................................154

8.2.1. Overload Operation................................................................................................... 1548.2.2. Operand Size.............................................................................................................1558.2.3. Signed Division.......................................................................................................... 1558.2.4. Divide By Zero........................................................................................................... 1558.2.5. Unsigned Square Root.............................................................................................. 155

8.3. Special Considerations.............................................................................................................1558.4. Extra Information...................................................................................................................... 1558.5. Examples..................................................................................................................................1568.6. API Overview............................................................................................................................156

8.6.1. Structure Definitions.................................................................................................. 1568.6.2. Function Definitions................................................................................................... 156

8.7. Extra Information for DIVAS Driver...........................................................................................1608.7.1. Acronyms...................................................................................................................1608.7.2. Dependencies............................................................................................................1608.7.3. Errata......................................................................................................................... 1608.7.4. Module History...........................................................................................................160

8.8. Examples for DIVAS Driver...................................................................................................... 1608.8.1. Quick Start Guide for DIVAS - No Overload.............................................................. 1618.8.2. Quick Start Guide for DIVAS - Overload....................................................................164

9. SAM Event System (EVENTS) Driver................................................................... 1689.1. Prerequisites.............................................................................................................................1689.2. Module Overview......................................................................................................................168

9.2.1. Event Channels......................................................................................................... 1699.2.2. Event Users............................................................................................................... 1699.2.3. Edge Detection.......................................................................................................... 1699.2.4. Path Selection............................................................................................................1699.2.5. Physical Connection.................................................................................................. 1709.2.6. Configuring Events.................................................................................................... 170

9.3. Special Considerations.............................................................................................................1719.4. Extra Information...................................................................................................................... 1719.5. Examples..................................................................................................................................171

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

5

9.6. API Overview............................................................................................................................1719.6.1. Variable and Type Definitions.................................................................................... 1719.6.2. Structure Definitions.................................................................................................. 1719.6.3. Macro Definitions....................................................................................................... 1729.6.4. Function Definitions................................................................................................... 1729.6.5. Enumeration Definitions.............................................................................................181

9.7. Extra Information for EVENTS Driver.......................................................................................1829.7.1. Acronyms...................................................................................................................1829.7.2. Dependencies............................................................................................................1829.7.3. Errata......................................................................................................................... 1829.7.4. Module History...........................................................................................................182

9.8. Examples for EVENTS Driver...................................................................................................1829.8.1. Quick Start Guide for EVENTS - Basic......................................................................1829.8.2. Quick Start Guide for EVENTS - Interrupt Hooks...................................................... 185

10. SAM External Interrupt (EXTINT) Driver............................................................... 19110.1. Prerequisites.............................................................................................................................19110.2. Module Overview......................................................................................................................191

10.2.1. Logical Channels....................................................................................................... 19110.2.2. NMI Channels............................................................................................................ 19210.2.3. Input Filtering and Detection......................................................................................19210.2.4. Events and Interrupts.................................................................................................19210.2.5. Physical Connection.................................................................................................. 192

10.3. Special Considerations.............................................................................................................19310.4. Extra Information...................................................................................................................... 19310.5. Examples..................................................................................................................................19310.6. API Overview............................................................................................................................193

10.6.1. Variable and Type Definitions.................................................................................... 19310.6.2. Structure Definitions.................................................................................................. 19410.6.3. Macro Definitions....................................................................................................... 19510.6.4. Function Definitions................................................................................................... 19510.6.5. Enumeration Definitions.............................................................................................201

10.7. Extra Information for EXTINT Driver.........................................................................................20210.7.1. Acronyms...................................................................................................................20210.7.2. Dependencies............................................................................................................20310.7.3. Errata......................................................................................................................... 20310.7.4. Module History...........................................................................................................203

10.8. Examples for EXTINT Driver.................................................................................................... 20310.8.1. Quick Start Guide for EXTINT - Basic....................................................................... 20310.8.2. Quick Start Guide for EXTINT - Callback.................................................................. 205

11. SAM Frequency Meter (FREQM) Driver................................................................20811.1. Prerequisites.............................................................................................................................20811.2. Module Overview......................................................................................................................20811.3. Special Considerations.............................................................................................................20811.4. Extra Information...................................................................................................................... 20911.5. Examples..................................................................................................................................20911.6. API Overview............................................................................................................................209

11.6.1. Variable and Type Definitions.................................................................................... 209

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

6

11.6.2. Structure Definitions.................................................................................................. 20911.6.3. Function Definitions................................................................................................... 21011.6.4. Enumeration Definitions.............................................................................................214

11.7. Extra Information for FREQM Driver........................................................................................ 21511.7.1. Acronyms...................................................................................................................21511.7.2. Dependencies............................................................................................................21511.7.3. Errata......................................................................................................................... 21511.7.4. Module History...........................................................................................................215

11.8. Examples for FREQM Driver....................................................................................................21511.8.1. Quick Start Guide for FREQM - Basic....................................................................... 21611.8.2. Quick Start Guide for FREQM - Callback.................................................................. 218

12. SAM Non-Volatile Memory (NVM) Driver.............................................................. 22212.1. Prerequisites.............................................................................................................................22212.2. Module Overview......................................................................................................................222

12.2.1. Driver Feature Macro Definition.................................................................................22212.2.2. Memory Regions........................................................................................................22312.2.3. Region Lock Bits........................................................................................................22412.2.4. Read/Write.................................................................................................................224

12.3. Special Considerations.............................................................................................................22412.3.1. Page Erasure.............................................................................................................22412.3.2. Clocks........................................................................................................................ 22412.3.3. Security Bit.................................................................................................................224

12.4. Extra Information...................................................................................................................... 22512.5. Examples..................................................................................................................................22512.6. API Overview............................................................................................................................225

12.6.1. Structure Definitions.................................................................................................. 22512.6.2. Macro Definitions....................................................................................................... 22712.6.3. Function Definitions................................................................................................... 22712.6.4. Enumeration Definitions.............................................................................................234

12.7. Extra Information for NVM Driver............................................................................................. 23912.7.1. Acronyms...................................................................................................................23912.7.2. Dependencies............................................................................................................23912.7.3. Errata......................................................................................................................... 23912.7.4. Module History...........................................................................................................239

12.8. Examples for NVM Driver.........................................................................................................24012.8.1. Quick Start Guide for NVM - Basic............................................................................ 240

13. SAM Peripheral Access Controller (PAC) Driver................................................... 24313.1. Prerequisites.............................................................................................................................24313.2. Module Overview......................................................................................................................243

13.2.1. Locking Scheme........................................................................................................ 24313.2.2. Recommended Implementation.................................................................................24413.2.3. Why Disable Interrupts.............................................................................................. 24613.2.4. Run-away Code......................................................................................................... 24713.2.5. Faulty Module Pointer................................................................................................24913.2.6. Use of __no_inline..................................................................................................... 24913.2.7. Physical Connection.................................................................................................. 249

13.3. Special Considerations.............................................................................................................249

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

7

13.3.1. Non-Writable Registers..............................................................................................24913.3.2. Reading Lock State................................................................................................... 249

13.4. Extra Information...................................................................................................................... 25013.5. Examples..................................................................................................................................25013.6. API Overview............................................................................................................................250

13.6.1. Macro Definitions....................................................................................................... 25013.6.2. Function Definitions................................................................................................... 251

13.7. Extra Information for PAC Driver.............................................................................................. 25313.7.1. Acronyms...................................................................................................................25313.7.2. Dependencies............................................................................................................25413.7.3. Errata......................................................................................................................... 25413.7.4. Module History...........................................................................................................254

13.8. Examples for PAC Driver..........................................................................................................25413.8.1. Quick Start Guide for PAC - Basic............................................................................. 254

13.9. List of Non-Write Protected Registers...................................................................................... 256

14. SAM Port (PORT) Driver....................................................................................... 25914.1. Prerequisites.............................................................................................................................25914.2. Module Overview......................................................................................................................259

14.2.1. Driver Feature Macro Definition.................................................................................25914.2.2. Physical and Logical GPIO Pins................................................................................ 26014.2.3. Physical Connection.................................................................................................. 260

14.3. Special Considerations.............................................................................................................26014.4. Extra Information...................................................................................................................... 26014.5. Examples..................................................................................................................................26014.6. API Overview............................................................................................................................261

14.6.1. Structure Definitions.................................................................................................. 26114.6.2. Macro Definitions....................................................................................................... 26114.6.3. Function Definitions................................................................................................... 26214.6.4. Enumeration Definitions.............................................................................................268

14.7. Extra Information for PORT Driver........................................................................................... 26914.7.1. Acronyms...................................................................................................................26914.7.2. Dependencies............................................................................................................26914.7.3. Errata......................................................................................................................... 26914.7.4. Module History...........................................................................................................269

14.8. Examples for PORT Driver.......................................................................................................26914.8.1. Quick Start Guide for PORT - Basic.......................................................................... 270

15. SAM RTC Count (RTC COUNT) Driver.................................................................27215.1. Prerequisites.............................................................................................................................27215.2. Module Overview......................................................................................................................272

15.2.1. Driver Feature Macro Definition.................................................................................27315.3. Compare and Overflow.............................................................................................................273

15.3.1. Periodic Events..........................................................................................................27315.3.2. Digital Frequency Correction..................................................................................... 27415.3.3. RTC Tamper Detect................................................................................................... 274

15.4. Special Considerations.............................................................................................................27515.4.1. Clock Setup............................................................................................................... 275

15.5. Extra Information...................................................................................................................... 276

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

8

15.6. Examples..................................................................................................................................27615.7. API Overview............................................................................................................................276

15.7.1. Structure Definitions.................................................................................................. 27615.7.2. Macro Definitions....................................................................................................... 27715.7.3. Function Definitions................................................................................................... 27915.7.4. Enumeration Definitions.............................................................................................292

15.8. RTC Tamper Detect..................................................................................................................29615.9. Extra Information for RTC COUNT Driver................................................................................ 296

15.9.1. Acronyms...................................................................................................................29615.9.2. Dependencies............................................................................................................29715.9.3. Errata......................................................................................................................... 29715.9.4. Module History...........................................................................................................297

15.10. Examples for RTC (COUNT) Driver......................................................................................... 29715.10.1. Quick Start Guide for RTC (COUNT) - Basic.............................................................29815.10.2. Quick Start Guide for RTC (COUNT) - Callback........................................................30015.10.3. Quick Start Guide for RTC Tamper with DMA............................................................303

16. SAM RTC Calendar (RTC CAL) Driver..................................................................30716.1. Prerequisites.............................................................................................................................30716.2. Module Overview......................................................................................................................307

16.2.1. Driver Feature Macro Definition.................................................................................30816.2.2. Alarms and Overflow................................................................................................. 30816.2.3. Periodic Events..........................................................................................................30816.2.4. Digital Frequency Correction..................................................................................... 30916.2.5. RTC Tamper Detect................................................................................................... 309

16.3. Special Considerations.............................................................................................................30916.3.1. Year Limit...................................................................................................................30916.3.2. Clock Setup............................................................................................................... 310

16.4. Extra Information...................................................................................................................... 31116.5. Examples..................................................................................................................................31116.6. API Overview............................................................................................................................311

16.6.1. Structure Definitions...................................................................................................31116.6.2. Macro Definitions....................................................................................................... 31316.6.3. Function Definitions................................................................................................... 31416.6.4. Enumeration Definitions.............................................................................................327

16.7. RTC Tamper Detect..................................................................................................................33116.8. Extra Information for RTC (CAL) Driver....................................................................................332

16.8.1. Acronyms...................................................................................................................33216.8.2. Dependencies............................................................................................................33216.8.3. Errata......................................................................................................................... 33216.8.4. Module History...........................................................................................................332

16.9. Examples for RTC CAL Driver..................................................................................................33216.9.1. Quick Start Guide for RTC (CAL) - Basic...................................................................33316.9.2. Quick Start Guide for RTC (CAL) - Callback..............................................................335

17. SAM Sigma-Delta Analog-to-Digital Converter (SDADC) Driver........................... 34017.1. Prerequisites.............................................................................................................................34017.2. Module Overview......................................................................................................................340

17.2.1. Sample Clock.............................................................................................................340

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

9

17.2.2. Gain and Offset Correction........................................................................................ 34117.2.3. Window Monitor......................................................................................................... 34117.2.4. Events........................................................................................................................341

17.3. Special Considerations.............................................................................................................34117.4. Extra Information...................................................................................................................... 34117.5. Examples..................................................................................................................................34117.6. API Overview............................................................................................................................342

17.6.1. Variable and Type Definitions.................................................................................... 34217.6.2. Structure Definitions.................................................................................................. 34217.6.3. Macro Definitions....................................................................................................... 34417.6.4. Function Definitions................................................................................................... 34417.6.5. Enumeration Definitions.............................................................................................354

17.7. Extra Information for SDADC Driver.........................................................................................35617.7.1. Acronyms...................................................................................................................35617.7.2. Dependencies............................................................................................................35717.7.3. Errata......................................................................................................................... 35717.7.4. Module History...........................................................................................................357

17.8. Examples for SDADC Driver.................................................................................................... 35717.8.1. Quick Start Guide for SDADC - Basic........................................................................35717.8.2. Quick Start Guide for SDADC - Callback...................................................................359

18. SAM Serial USART (SERCOM USART) Driver.....................................................36318.1. Prerequisites.............................................................................................................................36318.2. Module Overview......................................................................................................................363

18.2.1. Driver Feature Macro Definition.................................................................................36418.2.2. Frame Format............................................................................................................ 36418.2.3. Synchronous Mode....................................................................................................36518.2.4. Asynchronous Mode.................................................................................................. 36518.2.5. Parity..........................................................................................................................36518.2.6. GPIO Configuration................................................................................................... 366

18.3. Special Considerations.............................................................................................................36618.4. Extra Information...................................................................................................................... 36618.5. Examples..................................................................................................................................36618.6. API Overview............................................................................................................................366

18.6.1. Variable and Type Definitions.................................................................................... 36618.6.2. Structure Definitions.................................................................................................. 36618.6.3. Macro Definitions....................................................................................................... 37018.6.4. Function Definitions................................................................................................... 37118.6.5. Enumeration Definitions.............................................................................................384

18.7. Extra Information for SERCOM USART Driver........................................................................ 39018.7.1. Acronyms...................................................................................................................39018.7.2. Dependencies............................................................................................................39018.7.3. Errata......................................................................................................................... 39118.7.4. Module History...........................................................................................................391

18.8. Examples for SERCOM USART Driver....................................................................................39118.8.1. Quick Start Guide for SERCOM USART - Basic....................................................... 39218.8.2. Quick Start Guide for SERCOM USART - Callback.................................................. 39418.8.3. Quick Start Guide for Using DMA with SERCOM USART.........................................39618.8.4. Quick Start Guide for SERCOM USART LIN.............................................................402

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

10

18.9. SERCOM USART MUX Settings..............................................................................................407

19. SAM I2C Master Mode (SERCOM I2C) Driver...................................................... 40819.1. Prerequisites.............................................................................................................................40819.2. Module Overview......................................................................................................................408

19.2.1. Driver Feature Macro Definition.................................................................................40919.2.2. Functional Description............................................................................................... 40919.2.3. Bus Topology............................................................................................................. 40919.2.4. Transactions.............................................................................................................. 41019.2.5. Multi Master................................................................................................................41119.2.6. Bus States................................................................................................................. 41219.2.7. Bus Timing................................................................................................................. 41219.2.8. Operation in Sleep Modes......................................................................................... 413

19.3. Special Considerations.............................................................................................................41319.3.1. Interrupt-driven Operation..........................................................................................413

19.4. Extra Information...................................................................................................................... 41319.5. Examples..................................................................................................................................41319.6. API Overview............................................................................................................................414

19.6.1. Structure Definitions.................................................................................................. 41419.6.2. Macro Definitions....................................................................................................... 41519.6.3. Function Definitions................................................................................................... 41619.6.4. Enumeration Definitions.............................................................................................430

19.7. Extra Information for SERCOM I2C Driver............................................................................... 43219.7.1. Acronyms...................................................................................................................43219.7.2. Dependencies............................................................................................................43219.7.3. Errata......................................................................................................................... 43219.7.4. Module History...........................................................................................................432

19.8. Examples for SERCOM I2C Driver........................................................................................... 43319.8.1. Quick Start Guide for SERCOM I2C Master - Basic.................................................. 43319.8.2. Quick Start Guide for SERCOM I2C Master - Callback............................................. 43619.8.3. Quick Start Guide for Using DMA with SERCOM I2C Master....................................439

20. SAM I2C Slave Mode (SERCOM I2C) Driver........................................................ 44420.1. Prerequisites.............................................................................................................................44420.2. Module Overview......................................................................................................................444

20.2.1. Driver Feature Macro Definition.................................................................................44520.2.2. Functional Description............................................................................................... 44520.2.3. Bus Topology............................................................................................................. 44520.2.4. Transactions.............................................................................................................. 44620.2.5. Multi Master............................................................................................................... 44720.2.6. Bus States................................................................................................................. 44820.2.7. Bus Timing................................................................................................................. 44820.2.8. Operation in Sleep Modes......................................................................................... 449

20.3. Special Considerations.............................................................................................................44920.3.1. Interrupt-driven Operation..........................................................................................449

20.4. Extra Information...................................................................................................................... 44920.5. Examples..................................................................................................................................44920.6. API Overview............................................................................................................................450

20.6.1. Structure Definitions.................................................................................................. 450

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

11

20.6.2. Macro Definitions....................................................................................................... 45120.6.3. Function Definitions................................................................................................... 45320.6.4. Enumeration Definitions.............................................................................................464

20.7. Extra Information for SERCOM I2C Driver............................................................................... 46620.7.1. Acronyms...................................................................................................................46620.7.2. Dependencies............................................................................................................46620.7.3. Errata......................................................................................................................... 46620.7.4. Module History...........................................................................................................466

20.8. Examples for SERCOM I2C Driver........................................................................................... 46620.8.1. Quick Start Guide for SERCOM I2C Slave - Basic.................................................... 46720.8.2. Quick Start Guide for SERCOM I2C Slave - Callback............................................... 46920.8.3. Quick Start Guide for Using DMA with SERCOM I2C Slave......................................472

21. SAM Serial Peripheral Interface (SERCOM SPI) Driver........................................47721.1. Prerequisites.............................................................................................................................47721.2. Module Overview......................................................................................................................477

21.2.1. Driver Feature Macro Definition.................................................................................47821.2.2. SPI Bus Connection...................................................................................................47821.2.3. SPI Character Size.................................................................................................... 47921.2.4. Master Mode..............................................................................................................47921.2.5. Slave Mode................................................................................................................47921.2.6. Data Modes............................................................................................................... 47921.2.7. SERCOM Pads..........................................................................................................48021.2.8. Operation in Sleep Modes......................................................................................... 48021.2.9. Clock Generation....................................................................................................... 480

21.3. Special Considerations.............................................................................................................48021.3.1. pinmux Settings......................................................................................................... 480

21.4. Extra Information...................................................................................................................... 48121.5. Examples..................................................................................................................................48121.6. API Overview............................................................................................................................481

21.6.1. Variable and Type Definitions.................................................................................... 48121.6.2. Structure Definitions.................................................................................................. 48121.6.3. Macro Definitions....................................................................................................... 48321.6.4. Function Definitions................................................................................................... 48421.6.5. Enumeration Definitions.............................................................................................499

21.7. Extra Information for SERCOM SPI Driver...............................................................................50321.7.1. Acronyms...................................................................................................................50321.7.2. Dependencies............................................................................................................50321.7.3. Workarounds Implemented by Driver........................................................................ 50321.7.4. Module History...........................................................................................................503

21.8. Examples for SERCOM SPI Driver.......................................................................................... 50421.8.1. Quick Start Guide for SERCOM SPI Master - Polled................................................ 50421.8.2. Quick Start Guide for SERCOM SPI Slave - Polled.................................................. 50721.8.3. Quick Start Guide for SERCOM SPI Master - Callback.............................................51021.8.4. Quick Start Guide for SERCOM SPI Slave - Callback...............................................51421.8.5. Quick Start Guide for Using DMA with SERCOM SPI............................................... 517

21.9. MUX Settings............................................................................................................................52721.9.1. Master Mode Settings................................................................................................52721.9.2. Slave Mode Settings..................................................................................................528

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

12

22. SAM System (SYSTEM) Driver............................................................................. 52922.1. Prerequisites.............................................................................................................................52922.2. Module Overview......................................................................................................................529

22.2.1. Voltage Regulator...................................................................................................... 52922.2.2. Voltage References................................................................................................... 52922.2.3. System Reset Cause................................................................................................. 53022.2.4. Sleep Modes..............................................................................................................530

22.3. Special Considerations.............................................................................................................53022.4. Extra Information...................................................................................................................... 53022.5. Examples..................................................................................................................................53122.6. API Overview............................................................................................................................531

22.6.1. Structure Definitions.................................................................................................. 53122.6.2. Function Definitions................................................................................................... 53122.6.3. Enumeration Definitions.............................................................................................536

22.7. Extra Information for SYSTEM Driver.......................................................................................53722.7.1. Acronyms...................................................................................................................53722.7.2. Dependencies............................................................................................................53722.7.3. Errata......................................................................................................................... 53722.7.4. Module History...........................................................................................................537

23. SAM System Clock Management (SYSTEM CLOCK) Driver................................53923.1. Prerequisites.............................................................................................................................53923.2. Module Overview......................................................................................................................539

23.2.1. Clock Sources............................................................................................................53923.2.2. CPU / Bus Clocks...................................................................................................... 54023.2.3. Clock Masking........................................................................................................... 54023.2.4. Generic Clocks.......................................................................................................... 540

23.3. Special Considerations.............................................................................................................54223.4. Extra Information...................................................................................................................... 54223.5. Examples..................................................................................................................................54223.6. API Overview............................................................................................................................542

23.6.1. Structure Definitions.................................................................................................. 54223.6.2. Function Definitions................................................................................................... 54723.6.3. Enumeration Definitions.............................................................................................562

23.7. Extra Information for SYSTEM CLOCK Driver......................................................................... 56923.7.1. Acronyms...................................................................................................................56923.7.2. Dependencies............................................................................................................56923.7.3. Errata......................................................................................................................... 56923.7.4. Module History...........................................................................................................569

23.8. Examples for System Clock Driver...........................................................................................57023.8.1. Quick Start Guide for SYSTEM CLOCK - Basic........................................................ 57023.8.2. Quick Start Guide for SYSTEM CLOCK - GCLK Configuration.................................572

24. SAM System Interrupt (SYSTEM INTERRUPT) Driver......................................... 57624.1. Prerequisites.............................................................................................................................57624.2. Module Overview......................................................................................................................576

24.2.1. Critical Sections......................................................................................................... 57624.2.2. Software Interrupts.................................................................................................... 576

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

13

24.3. Special Considerations.............................................................................................................57724.4. Extra Information...................................................................................................................... 57724.5. Examples..................................................................................................................................57724.6. API Overview............................................................................................................................577

24.6.1. Function Definitions................................................................................................... 57724.6.2. Enumeration Definitions.............................................................................................582

24.7. Extra Information for SYSTEM INTERRUPT Driver.................................................................59724.7.1. Acronyms...................................................................................................................59724.7.2. Dependencies............................................................................................................59724.7.3. Errata......................................................................................................................... 59724.7.4. Module History...........................................................................................................597

24.8. Examples for SYSTEM INTERRUPT Driver.............................................................................59824.8.1. Quick Start Guide for SYSTEM INTERRUPT - Critical Section Use Case................59824.8.2. Quick Start Guide for SYSTEM INTERRUPT - Enable Module Interrupt Use Case. 598

25. SAM System Pin Multiplexer (SYSTEM PINMUX) Driver..................................... 60025.1. Prerequisites.............................................................................................................................60025.2. Module Overview......................................................................................................................600

25.2.1. Driver Feature Macro Definition.................................................................................60025.2.2. Physical and Logical GPIO Pins................................................................................ 60025.2.3. Peripheral Multiplexing.............................................................................................. 60125.2.4. Special Pad Characteristics.......................................................................................60125.2.5. Physical Connection.................................................................................................. 601

25.3. Special Considerations.............................................................................................................60225.4. Extra Information...................................................................................................................... 60225.5. Examples..................................................................................................................................60225.6. API Overview............................................................................................................................602

25.6.1. Structure Definitions.................................................................................................. 60225.6.2. Macro Definitions....................................................................................................... 60325.6.3. Function Definitions................................................................................................... 60325.6.4. Enumeration Definitions.............................................................................................606

25.7. Extra Information for SYSTEM PINMUX Driver........................................................................60825.7.1. Acronyms...................................................................................................................60825.7.2. Dependencies............................................................................................................60825.7.3. Errata......................................................................................................................... 60825.7.4. Module History...........................................................................................................608

25.8. Examples for SYSTEM PINMUX Driver................................................................................... 60825.8.1. Quick Start Guide for SYSTEM PINMUX - Basic...................................................... 608

26. SAM Timer/Counter (TC) Driver............................................................................ 61126.1. Prerequisites.............................................................................................................................61126.2. Module Overview......................................................................................................................611

26.2.1. Driver Feature Macro Definition.................................................................................61326.2.2. Functional Description............................................................................................... 61326.2.3. Timer/Counter Size.................................................................................................... 61326.2.4. Clock Settings............................................................................................................61426.2.5. Compare Match Operations.......................................................................................61526.2.6. One-shot Mode.......................................................................................................... 617

26.3. Special Considerations.............................................................................................................617

Atmel AT13526: ASF Manual (SAM C21) [APPLICATION NOTE]Atmel-42698A-ASF-Manual-(SAMC21)_AT13526_Application Note-09/2016

14

26.4. Extra Information...................................................................................................................... 61826.5. Examples..................................................................................................................................61826.6. API Overview............................................................................................................................618

26.6.1. Variable and Type Definitions.................................................................................... 61826.6.2. Structure Definitions.................................................................................................. 61826.6.3. Macro Definitions....................................................................................................... 62126.6.4. Function Definitions................................................................................................... 62326.6.5. Enumeration Definitions.............................................................................................632

26.7. Extra Information for TC Driver.................................................................................................63526.7.1. Acronyms...................................................................................................................63526.7.2. Dependencies............................................................................................................63526.7.3. Errata......................................................................................................................... 63526.7.4. Module History...........................................................................................................635

26.8. Examples for TC Driver............................................................................................................ 63626.8.1. Quick Start Guide for TC - Basic............................................................................... 63626.8.2. Quick Start Guide for TC - Match Frequency Wave Generation................................63926.8.3. Quick Start Guide for TC - Timer............................................................................... 64126.8.4. Quick Start Guide for TC - Callback.......................................................................... 64426.8.5. Quick Start Guide for Using DMA with TC.................................................................648

27. SAM Timer Counter for Control Applications (TCC) Driver................................... 65527.1. Prerequisites.............................................................................................................................65527.2. Module Overview......................................................................................................................655

27.2.1. Functional Description............................................................................................... 65627.2.2. Base Timer/Counter...................................................................................................65727.2.3. Capture Operations................................................................................................... 65927.2.4. Compare Match Operation........................................................................................ 66027.2.5. Waveform Extended Controls.................................................................................... 66127.2.6. Double and Circular Buffering....................................................................................66327.2.7. Sleep Mode................................................................................................................663

27.3. Special Considerations.............................................................................................................66327.3.1. Driver Feature Macro Definition.................................................................................66327.3.2. Module Features........................................................................................................66327.3.3. Channels vs. Pinouts................................................................................................. 664

27.4. Extra Information...................................................................................................................... 66427.5. Examples..................................................................................................................................66427.6. API Overview............................................................................................................................664

27.6.1. Variable and Type Definitions.................................................................................... 66427.6.2. Structure Definitions.................................................................................................. 66527.6.3. Macro Definitions....................................................................................................... 67027.6.4. Function Definitions................................................................................................... 67227.6.5. Enumeration Definitions.............................................................................................687

27.7. Extra Information for TCC Driver..............................................................................................69727.7.1. Acronyms...................................................................................................................69727.7.2. Dependencies............................................................................................................69727.7.3. Errata......................................................................................................................... 69727.7.4. Module History...........................................................................................................697

27.8. Examples for TCC Driver..........................................................................................................69727.8.1.