MEM800-005 MEM380-006 Control Applications Using DSP Lab …€¦ · Cntrl Using DSP, Lab 1: F28335...

Cntrl Using DSP, Lab 1: F28335 & CCSv5 March 2013

B.C. Chang & M.U. Salman, MEM Dept. Drexel Univ. 1/19

MEM800-005 MEM380-006

Control Applications Using DSP

Lab 1

Getting Started with DSP F28355 & CCSv5

B.C. Chang and Mishah U. Salman

Department of Mechanical Engineering & Mechanics

Drexel University

2013



1. Objective

The objective of this lab is to provide hands-on experience for the students to get acquainted with the Texas Instruments DSP microprocessor TMS320F28335 and the Code Composer Studio V5.2, which is TI’s integrated development environment (IDE) for TI embedded processors, and use them to assemble, debug, and run a C program project to generate controllable PWM signals that can control virtually everything accessible.

The enhanced pulse width modulator (ePWM) peripheral is a key element in digital control and switch mode power control systems. The ePWM peripheral performs a power-efficient digital to analog conversion (DAC) function, where the duty cycle is equivalent to a DAC analog value.

In this lab, you will

• Use a DSP microprocessor to generate 3 pairs of PWM signals: i) ePWM1: Active high PWMs, Use Up Count Mode ii) ePWM2: Active low PWM, Complementary, Use Up-Down Count Mode iii) ePWM3: Active high PWMs, Use Up-Down Count Mode

• Program a DSP microprocessor in C. 2. Brief Description of the TI TMS320F28335 DSP Microprocessor

A DSP microprocessor is an embedded computer. Similar to the processor inside a personal computer, a DSP microprocessor is a high-power computational device.

The Texas Instruments (TI) F28335 DSP will be utilized for this lab. This specific DSP microprocessor contains various onboard peripherals that allow it to interface with various types of sensors, actuators, and secondary processors. Because of these peripherals, the F28335 can easily be implemented as a microcontroller. For ease of use, the F28335 will be used within an evaluation system known as the Spectrum Digital F28335 eZdsp.

P8 P9



eZdsp F28335. The P8 port cluster contains various programmable digital I/O pins. The These interfaces will be utilized in this lab.

P8, I/O Connectors

Pin # Signal Pin # Signal

1 +3.3V/+5V/NC * 2 +3.3V/+5V/NC *

3 MUX_GPIO29_SCITXDA_XA19 4 MUX_GPIO28_SCIRXDA_XZCS6n

5 GPIO14_TZ3n_XHOLD_SCITXDB_MCLKXB 6 GPIO20_EAEP1A_MXDA_CANTXB

7 GPIO21_EQEP18_MDRA_CANRXB 8 GPIO23_EQEP1_MFSXA_SCIRXDB

9 GPIO0_EPWM1A 10 GPIO1_EPWM1B/ECAP6/MFSRB

11 GPIO2_EPWM2A 12 GPIO3_EPWM2B_ECAP5_MCLKRB

13 GPIO4_EPWM3A 14 GPIO5_EPWM3B_MFSRA_ECAP1

15 GPIO27_ECAP4_EQEP2S_MFSXB 16 GPIO6_EPWMN4A_EPWMSYNCI/EPWMSYNCO

17 GPIO13_TZ2N_CANRXB_MDRB 18 GPIO34_ECAP1_XREADY

19 GND 20 GND

21 GPIO7_EPWM4B_MCLKRA_ECAP2 22 GPIO15TZ4n_XHOLDA_SCIRXDB_MFSXB

23 GPIO16_SPISIMOA_CANTXB_TZ5n 24 GPIO17_SPISOMIA_CANRXB_TZ6n

25 GPIO18_SPICLKA_SCITXDB_CANRXA 26 GPIO19_SPISTAn_SCIRXDB_CANTXA

27 _MUX_GPIO31_CANRXA_XA17 28 MUX_GPIO30_CANRXA_XA18

29 MUX_GPIO11_EPWM6B_SCIRXDB_ECAP4 30 MUX_GPIO8EPWM5A_CANTXB_ADCSOCA0nP3

31 MUX_GPIO9_EPWM5B_SCITXDB_ECAP3 32 MUX_GPIO10_EPWM6A_CANRXB_ADCASOCB0n

33 MUX_GPIO22 34 GPIO25_ECAP2_EPEQ2B_MDRB

35 GPIO26_ECAP3_EQEP21_MCLKXB 36 GPIO32_SDAA_EPWMSYNCI_ADCSOCAOn

37 GPIO12_TZ1N_CANTXB_MDXB 38 GPIO33_SCLA_EPWNSYNCVO_ADCSOCBOn

39 GND 40 GND

F28335 eZdsp P4/P8/P7, Digital Interface Connector

3. Connect the DSP F28335 to PC and the DAQ with LabVIEW VI

DO NOT OPEN THE SOCKET on the board to avoid damaging the DSP chip inside. Connect the NI USB-6211 (DAQ) box to PC via USB cable and connect AI0, AI1, and AIGND to eZdsp Pins P8: #9, #10 and P8: #19, respectively. A simple LabVIEW VI as follows will be needed to observe the PWM signals.

NI USB-6211 (DAQ) TI F28335 eZdsp

AI0 P8: #9 AI1 P8: #10

AIGND P8: #19





4. Get Started with the Code Composer Studio Version 5.2

http://processors.wiki.ti.com/index.php?title=C2000_Getting_Started_with_Code_Composer_Studio_v5 http://processors.wiki.ti.com/index.php/Main_Page C2000 Getting Started with Code Composer Studio v5

4A. Key terminologies in CCSv5

Workspaces: When you open CCSv5 the first time, you’ll be asked to select a workspace, which is a folder to store the information the settings, views, watch variables, etc. of your project.



Workbench is a CCSv5 GUI window that contains all the various views and resources used for development and debug.

Views are the windows that display the information within the workbench.

Perspectives: They are mainly two perspectives, ie., layouts of views, in the workbench window. These two are “CCS Edit” for project development and “CCS Debug” for debugging. You also can create custom perspectives.

4B. Starting up CCSv5

1. Open the Texas Instruments Code Composer Studio v5 (CCS v5) Start >> All Programs >> Texas Instruments >> Code Composer Studio v5. 2. The pop-up CCS window will appear either in the CCS Debug prospective or in the CCS Edit

prospective. You can click the button "CCS Edit" or "CCS Debug" on the upper right corner of the window to change the prospective back and forth. In the CCS Edit prospective shown in the following figure, you can see the empty space inside the "Project Explorer" view where the project files will reside after you create them.

3. You will also see the welcome window where you can click on “New Project” to start constructing a new project, on “Examples” to open existing Example projects, or on “Import Project” to migrate the projects created in older CCS versions like CCSv3 or CCSv4. You can even click “Getting Started” to watch the tutorial video.



4C. Create a Target Configuration File

A Target Configuration specifies the emulator, the device, and other information for CCSv5.

1. Go to the "View → Target Configurations" menu. 2. Click on the "New Target Configuration File" icon shown in the following:

3. Type a name for the Target Configuration File like “eZdspF28335.ccxml” and leave the “Use shared location” box checked.

4. Click “Finish” and then choose “Spectrum Digital DSK-EVM-eZdsp onboard_USB Emulator” as Connection and check the little square box at the Device EZDSPF28335.



5. Click on the "Save" button or use “File → Save” 6. Go to the "View → Target Configurations", Under “User-Defined”, you will see your new target

configuration. 7. Right-click the configuration and select “Set as Default” if you want to use this emulator and

device GEL file by default for all future projects opened in your workspace that do not have a target configuration assigned to them.

8. Alternatively, you can right-click the configuration and select “Link File to Project → xxxx” to associate this target configuration to this specific project in your workspace.



4D. Migrate a CCSv3.3 Project to CCSv5.2

In the following, we will migrate a project, 1s_epwm.pjt, from CCSv3.3 to CCSv5.2. The CCSv3.3 project, 1s_epwm.pjt, together with the associated C program, 1s_epwm.c and a gel file 1s_epwm.gel can be found in the folder 1s_epwm_orignal, which is inside the directory C:\tidcs\c28\DSP2833x\v131\CntrlDSP.

To start the migration process, you’ll do the following:

1. Duplicate the folder 1s_epwm_orignal in the same directory and rename the new folder as 1s_epwm. Note that the duplicated folder now consists of three files: 1s_epwm.pjt, 1s_epwm.c, and 1s_epwm.gel.

2. Make sure you are in the CCSv5.2 Edit prospective – the “CCS Edit” button on the upper right corner is selected.

3. In the CCSv5.2 Edit prospective, select "Project → Import Legacy CCSv3.3 Project ". 4. In the pop-up “Import Legacy CCS Projects” window, browse to select the following CCSv3.3

project file: C:\tidcs\c28\DSP2833x\v131\CntrlDSP\1s_epwm\1s_epwm.pjt



5. Press the "Next " button, and select a compiler.

6. Press the "Next " button, and specify whether DSP/BIOS support should be enabled or automatically determined. If you do not know, then select "Automatically Determine DSP/BIOS support enablement".



7. Press the "Next" button. Then de-select "Use common root for all migrated projects" to allow CCS to automatically determine the unique common root for all files referenced by the project.

8. Press the "Finish" button.

Now you have migrated a CCS3.3 project to CCSv5.2. This process has created a new folder (also named 1s_epwm) with the new CCSv5.2 files .ccsproject, .cproject, .project, and a folder .settings. Furthermore, the successfully migrated CCSv5.2 project, 1s_epwm, now appears in the Project Explorer View window.



If you double click the C program file, 1s_epwm.c, in the Project Explorer, you’ll see the file open to show the C code in the new View window, 1s_epwm.c.



4E. Link the Target Configuration File eZdspF28335.ccxml to the Project 1s_epwm.pjt

1. Go to the "View → Target Configurations", Under “User-Defined”, you will see your newly created target configuration file, eZdspF28335.ccxml.

2. Right-click the configuration and select “Link File to Project → 1s_epwm” to associate this target configuration to the project 1s_epwm.pjt.

3. Then you will see the target configuration file eZdspF28335.ccxml appear in the Project Explorer View window.



Now, the project 1s_epwm.pjt is ready for CCSv5.2. In the following, you will Debug, Build, and Run the project to generate the designated PWM signals.

5. Generate PWM Signals Using the Project 1s_epwm.pjt

Three ePWM modules of F28335: ePWM1, ePWM2, and ePWM3 will be used in this project to generate PWM signals. The ePWM module represents one complete PWM channel which is capable of generating two PWM outputs: EPWMxA and EPWMxB. 5A. Debug, Build and Run the Project 1. Select the project by clicking the project's name 1s_epwm in the "Project Explorer" view. 2. Click on the green bug (debug button) on the tool bar as shown in the following figure.

3. The debugging process will do the following:

(i) Save all open files in the project selected (ii) Build the selected project and create an executable file 1s_epwm.out, which appears in the folder

Debug (iii) Automatically switched the CCS Debug perspective

4. The "Debug" view is now visible.

(i) This view should always be open. Do not close it. If it is accidently closed, you can open it again using the "view → debug" menu item.

(ii) It allows you to connect the target device and control it (run, suspend, etc.)



5. Select "Run → Load → Load Program" to load the executable file 1s_epwm.out to the target device. In the Load Program pop-up window, press the “OK” button.

6. Run → Resume 7. Observe the following PWM signals: Observe the waveform of ePWM1 - ePWM3 on an oscilloscope or LabVIEW with DAQ card. EPWM1A is on GPIO0, eZdsp P8:pin9 EPWM1B is on GPIO1, eZdsp P8:pin10 EPWM2A is on GPIO2, eZdsp P8:pin11 EPWM2B is on GPIO3, eZdsp P8:pin12 EPWM3A is on GPIO4, eZdsp P8:pin13 EPWM3B is on GPIO5, eZdsp P8:pin14

8. Select View → Expresions. Type the names of the registers on the Expressions view as shown at the top of the CCS window.

EPwm1Regs.TBPRD EPwm1Regs.TBCTR EPwm1Regs.CMPA.half.CMPA EPwm1Regs.CMPB



EPwm2Regs.TBPRD EPwm2Regs.TBCTR EPwm2Regs.CMPA.half.CMPA EPwm2Regs.CMPB EPwm3Regs.TBPRD EPwm3Regs.TBCTR EPwm3Regs.CMPA.half.CMPA EPwm3Regs.CMPB

9. Select Run → Suspend. Observe the values of the registers in the following "Expressions" view.

10. Compute the period and duty cycle of these PWM signals based on the programmed register values

and verify the results by the observed PWM waveforms on the oscilloscope or the LabVIEW Front Panel.

5B. Use the Expressions view to Manipulate the Register Values 1. Type to change the value of EPwm1Regs.CMPA.half.CMPA that would change the duty cycle of

the PWM signal to 15% and verify the results by observing the PWM waveforms on the LabVIEW graphs.

2. Repeat Step 5B 1 to change the duty cycle of the PWM signal to 80% and verify the results by the observed PWM waveforms on the LabVIEW graphs.

3. Repeat Steps 5B 1 and 5B 2 of EPwm2Regs.CMPA.half.CMPA and compute the periods and duty cycles, and verify them by observing the PWM waveforms on the LabVIEW graphs.

4. Repeat Steps 5B 1 and 5B 2 of EPwm3Regs.CMPA.half.CMPA and compute the periods and duty cycles, and verify them by observing the PWM waveforms on the LabVIEW graphs.



5C. Enable Real-Time Mode to Observe Continuous Update of the Values in the Expresions view 1. Click on the clock icon at the top of the CCS Debug perspective.

2. CCS will ask if you would like to change bit 1 of the ST1 status register to 0. This is required to enter

real-time mode. 3. Select "Yes". 4. In the upper right corner of the Expressions view, click the "Continuous Refresh" button. 5. Observe how the values of registers are changing with time. 6. Repeat 5B in real-time mode.

6. Observations and Discussions

6A. Discuss how to change the period of a PWM signal. 6B. Discuss how to change the duty cycle of a PWM signal. 6C. Discuss how to modify a C program that produces an active high PWM to an active low PWM. 6D. In a later lab, you will be asked to modify one of the above PWM Example programs to

produce a pair of PWM signals that can be used together with a H-bridge to change the velocity (including direction) of a DC motor.

Appendix A:

//============================================================================= // FILE: 1s_epwm.c // // This program is modified from Example_2833xEpwmDeadBand.c, // // by B.C. Chang, Mishah U. Salman, Drexel Univ. // on April 5, 2010 //



// This program requires the // DSP2833x/DSP2823x C/C++ Header Files V1.31, released by TI on August 4, 2009. //========================================================================== // // Observe the waveform of ePWM1 - ePWM3 on an oscilloscope or LabVIEW // with DAQ card. // // EPWM1A is on GPIO0, eZdsp P8:pin9 // EPWM1B is on GPIO1, eZdsp P8:pin10 // // EPWM2A is on GPIO2, eZdsp P8:pin11 // EPWM2B is on GPIO3, eZdsp P8:pin12 // // EPWM3A is on GPIO4, eZdsp P8:pin13 // EPWM3B is on GPIO5, eZdsp P8:pin14 // // Use Expression View to observe // // EPwm1Regs.TBPRD // EPwm1Regs.TBCTR // EPwm1Regs.CMPA.half.CMPA // EPwm1Regs.CMPB // // EPwm2Regs.TBPRD // EPwm2Regs.TBCTR // EPwm2Regs.CMPA.half.CMPA // EPwm2Regs.CMPB // // EPwm3Regs.TBPRD // EPwm3Regs.TBCTR // EPwm3Regs.CMPA.half.CMPA // EPwm3Regs.CMPB // // DESCRIPTION: // // This example configures ePWM1, ePWM2 and ePWM3 for: // // 3 Examples are included: // * ePWM1: Active high PWMs, Use Up Count Mode // * ePWM2: Active low PWM, Complementary, Use Up-Down Count Mode // * ePWM3: Active high PWMs, Use Up-Down Count Mode //==========================================================================

Appendix B: ePWM1: White: ePWM1A, Red: ePWM1B,



Period by formula: Period by measurement: Duty cycle of ePWM1A by formula: Duty cycle of ePWM1B by measurement:

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