This demo gives an idea about interfacing multiplexed ... · 3 Demo 2 - 4 Digit Multiplexed...

1

Demo 2 - 4 Digit Multiplexed 7-Segment Display With 7 Segment I/P

www.MightyMicons.com

4 Digit Multiplexed 7-Segment Display With 7 Segment I/Pwww.MightyMicons.com

Introduction:

This demo gives an idea about interfacing multiplexed seven segment display with seven segment

data input. The interfacing can be verified using a 4 digit counter program which will counts from

H’0000 to H’FFFF.

Demo Hardware:

4 digits of seven segment LED displays are connected in multiplexed mode with seven segment

data input.

Connect P0 to the seven segments sequentially and the Port lines P30, P31, P32 and P33 to the

digit selection lines.

2




Circuit Connection:+

5V

+5V

+5V

+5V

+5V

+5V

+5V

+5V

+5V

+5V

+5V

CN

C

NC

C

PR

OG

RA

M

NO

RM

AL

+5V

EX

43

21

a b c d e f g h

GD F

C

D.P

D.P

D GFEC D.P

E

C

GFD

GD FE D.P

C E

AA

BAA B

BB

A B C D E F G

D.P

0.1u

FC

1

33P

FC

4

20M

HZ

XT

AL1

33P

FC

3

JP4

1 2 3

IN41

48D

1

CD

4010

6

U2

12

+ 4.7u

FC

6

10K

R1

T4

BC

557

R36

1K

U11

KLS 563 G

A7

B6

C4

D2

E1

F9

G10

C8

D.P

5

C3

T3

BC

557

R35

1K

U10

KLS 563 G

A7

B6

C4

D2

E1

F9

G10

C8

D.P

5

C3

U9

KLS 563 G

A7

B6

C4

D2

E1

F9

G10

C8

D.P

5

C3

R34

1K

T2

BC

557

R33

1K

T1

BC

557

U8

KLS 563 G

A7

B6

C4

D2

E1

F9

G10

C8

D.P

5

C3

R29

10K

R30

10K

R31

10K

R32

10K

U20

A

74LS

07

1 2

U20

B

74LS

07

3 4

U20

C

74LS

07

5 6

U20

D

74LS

07

9 8

JP6

12

34

R53

1K

0.1u

FC

2

CD

4010

6U

2

34

R1

4K7

JP2

123

RE

SE

T

SW

1

JP1 1

23

JP3

1 2 3R2

4K7

R48

10K

R38

56E

R43

56E

R40

56E

R42

56E

R44

56E

R41

56E

R37

56E

R39

56E

A1

2

A2

3

A3

4

A4

5

A5

6

A6

7

A7

8

A8

9

G19DIR1

B1

18

B2

17

B3

16

B4

15

B5

14

B6

13

B7

12

B8

11

VCC20GND

10

R8C

11/1

3U

1

P37

/TX

D10

/RX

D1

1

CN

VS

S2

RE

SE

T3

XO

UT

/P47

4

VSS5

XIN

/P46

6

VCC7

P17

/INT

1/C

NT

R0

8

P16

/CLK

09

P15

/RX

D0

10

P14

/TX

D0

11

P13

/KI3

12

P12

/KI2

13

P11

/KI1

14

P10

/KI0

15

P45

/INT

016

MO

DE

28

IVCC23

P30

/CN

TR

022

AVSS21

P31

/TZ

OU

T20

AV

CC

/VR

EF

19

P32

/INT

2/C

NT

R1

18

P33

/INT

3/T

CIN

17

P00

/AN

7/T

XD

1132

P01

/AN

631

P02

/AN

530

P03

/AN

429

P04

/AN

327

P05

/AN

226

P06

/AN

125

P07

/AN

024

BC

DN

ote:

Dot

ted

lines

indi

cate

the

requ

ired

conn

ectio

ns m

eant

for

the

appl

icat

ion.

3




Connections:

Port lines Display LinesP00 Segment a

P01 Segment b

P02 Segment c

P03 Segment d

P04 Segment e

P05 Segment f

P06 Segment g

P07 Segment dp

P30 Digit Selection Control for digit 1




Functional Description:

In this demo, a four digit counter program is provided to study the interfacing of seven segment

display in multiplexed mode with seven segment data input. The 4 digit counter will be displayed

on the display counting from H’0000 to H’FFFF.

Registers Used:

PD0 - Port 0 Direction Register

PD3 - Port 3 Direction Register

TXMR- Timer X mode Register

PREX- Prescaler X Register

TX - Timer X Register

TCSS- Timer Count Source Setting Register

4




Port Direction Register:

PD0 is set to H’FF to select all lines of port 0 (P00 to P07) as output lines to control seven

segment display. Port lines P30 to P33 are set as output lines by moving data H’0F to PD3

register.

TXMR - Timer X Mode Register:

5




Timer X mode register TXMR is loaded with H’00 to set timer mode.

PREX -Prescaler X Register:

The prescaler register PREX is loaded with 100 to divide the input selected clock to timer X by

100.

TX - Timer X Register:

The timer X register TX loaded with 100 to generate an interrupt at 1 milli second rate.

6




TCSS - Timer Count Source Setting Register:

The data H’03 is moved to Timer Count Source Setting Register TCSS to select “f2” as source

clock for Timer X.

Software Description:

In this demo, a four digit counter program is provided to study the interfacing of seven segment

display in multiplexed mode with seven segment data input.

Timer X is used to generate an interrupt at a rate of one milli second. In the timer X interrupt

service routine, the seven segment display is refreshed and the milli seconds are counted to get

one second delay. This milli second counter is used in main loop to get 1 second delay.

In the main loop, the timer X is initialized to generate interrupt at 1KHZ rate to refresh the display

and wait for one second. After a second, the count value is increment by one and displayed on

the 4 digit display. The process is repeated.

7




The files used in this demo are listed below:

Files Description

Demo2.C

The only file for this module, has the processing function for the 4 digit counter ,

timer X interrupt service routine and initialization routines for seven segment

display, timer X etc.

The functions in the file Demo2.C and short descriptions are listed below:

Files

Files Description

main

A 4 digit counter which will counts from H'0000 to H'FFFF.

Input: None. Output : None.

LEDInterrupt

Timer X interrupt service routine. Here the seven segment display was refreshed and the milli

seconds are counted to get one second delay. Input: None.

Output : None.

InitLEDDisplay

Timer X is initialized to generate an interrupt at a rate of one milli second.Timer X and variables

used for refreshing display. Input: None.

Output : None.

Initialize7SegmentMuxDisplay

This routine will initialize I/O lines used for seven segment display,

Input: None. Output : None.

Display4Digits

Displays the given 4 digit number on seven segment display.

Input: 4 Digit number. Output : None.

8




Program Flow:For Main Loop

Start

1 . I n i t i a l iz e P o r t 0 a so u tp u t p o r t a n d p o r tl i n e P 3 0 t o P 3 3 a soutput lines. In itia lizevariables to 0.

2 . In i t ia l ize T im e r X togenerate an interruptat 1 msec rate.

Check millisecond count with

999

< 999

> 999

Increm ent the counta n d d is p la y i t o nLED display.

9




For Timer X Interrupt Service Routine

Start

Get the lower 2 bitsof digit selection

variable (MuxData).(Only 4 digits)

Switch off all thedigits

Send the 7-segment datato port 0 and digitselection data for

currently selected digit toport 3.

Increment the currentlyselected digit

variable.(MuxData)

Return from Interrupt

Increment milli secondcount

Execute Demo:

After reset, the 4 digit counter will be displayed on the display counting from H’0000 to H’FFFF.

1 0




Use Topview Simulator to Verify the Design.

Open the project Demo2 in the R8C/Tiny System Simulator using Open Project option from

Project menu. The project window opens up along with the Demo2.c file. Use Build option from

Build menu to compile the project. An output window captures the compiler ouput.

Use Project -> Download Project from main menu to download the Demo2.mot file into the

simulator’s memory for simulation.

1 1




Open the LED Module settings window and do the settings to the 7-segment LED module as

shown. Connect 7 segments of the display to the port lines P00 to P07 and the 4 digit selection

lines to P30, P31, P32 and P33 respectively using radio buttons.

1 2




Then open the LED window usign the option View -> External Modules -> LED as shown

below and the Program Window.

Run the program using Go from the Run menu. The program will display a 4 digit counter in the

7-segment display and counts from H’0000 to H’FFFF and it is repeated.

Date post:	29-May-2018
Category:	Documents
Upload:	doanphuc
View:	250 times
Download:	0 times

This demo gives an idea about interfacing multiplexed ... · 3 Demo 2 - 4 Digit Multiplexed...

Documents