You have no items in your shopping cart.

Subtotal: 0.00

User Manual for 8279 Keyboard and Display Interface Card

Introduction of 8279 Keyboard and Display

8279 Keyboard and Display controller card designed to study the features of keyboard and Display controller PS- 8279 Interface card consist of 6 Nos. numbers of Common Cathode 7segment displays arranged in order with driver by using PNP transistors, and 8X2 Matrix keypad consist of 16 Nos. snap on keys arranged in matrix format, Address lines, Chip select lines and the Power lines are terminated with 50-pin connector.

Specification

8279 (keyboard and Display )

  • 40 pin keyboard and display IC
  • Simultaneous keyboard and Display operation.
  • 3 input mode such as scanned keyboard mode, scanned sensor mode and strobed input entry
  • 6 character Display
  • 8 character keyboard FIFO
  • Right or Left entry 6 Byte Display RAM
  • Programmable Scan Timing
  • 2 Key lockout or N-key Roll-over with contact debounce.
  • Auto Increment facility for easy programming
  • Display Interface : 6 No of Seven Segment
  • Matrix Key Interface : 18 No of snap on keys

 

50-pin Box Header

All data| control lines | Power lines terminated at box connector

50-pin FRC Cable

To connect host boards (Microcontroller/Micro Processor)

Card Features

  • 16 Nos. Tact Switch
  • 6 No of seven segment
  • 20-pin Box Connector

 

Kit Includes

  • 8279 keyboard and display IC
  • 8x2 Keypad matrix
  • 6 No of seven segment
  • Interface Cable

 

Hardware Description of 8279 Interface Card

keyboard and display is configured in the encoded mode. In the encoded mode, a binary count sequence is put on the scan lines SL0-SL3. These lines must be externally decoded to provide the scan lines for keyboard and display. A 3 to 8 decoder 74LS138 is provided for this purpose. The S0-S1 output lines of this decoder are connected to the two rows of the keyboard. And QA0 to QA7 is connected to 7 Segment Display

8279-Keyboard-and-Display-Interface-Card-block-diagram

a) PIN DIAGRAM OF 8279


8279-pin-out-diagram
 

b) PIN DIAGRAMOF 74LS138

74ls138-pin-configuration

Hardware Configuration of 8279 With 8051/8086/8085

 

 

50 PIN HEADER

8279

CONNECTIONS

OUTPUT

CONTROL LINES

RD

RD

Connect the 50 pin FRC cable to PS - 8279 interface card and trainer kit

 

 

8279 Output will be displayed on Seven Segment or Memory address Specified in the Program(D0 to D7)

WR

WR

From Decoder

CS

RST

RST

RST 5.5

IRQ

CLK

CLK

DATA LINES

D0

D0

D1

D1

D2

D2

D3

D3

D4

D4

D5

D5

D6

D6

D7

D7

VCC

VCC

VCC

Supply drawn from MCU/MPU.

Pin number 24 to 31 is connected to 7 segments. SL0 – SL2 is connected to decoder and SL2 is no connect RL0 – RL7 is connected to keypad

GND

GND

GND

 

Programs on Ps-Addon 8279 Interface Card


a) 8279 Interface With 8085


8085 Micro Processor on Board I/O Decoding Address

 

CONTROL

ADDRESS

Control REG

62H

Control Data

60H

 

Program 1:

 

Display data "a":

 

AIM:

To initialize 8279 and to display the character "A" in the first digit of the display. However, before sending codes to the display RAM, a write display RAM control word should be sent. Then, write the data to be displayed, to the data register.

 

ADDRESS

OPCODE

MNEMONICS

9100

3E 00

MVI A,00

9102

D3 62

OUT CNT

9104

3E CC

MVI A,CC

9106

D3 62

OUT CNT

9108

3E 90

MVI A,90 ;

910A

D3 62

OUT CNT

910C

3E 88

MVI A,98 ; data

910E

D3 60

OUT DAT

9110

3E FF

MVI A,FF

9112

D3 60

OUT DAT

9114

D3 60

OUT DAT

9116

D3 60

OUT DAT

9118

D3 60

OUT DAT

911A

D3 60

OUT DAT

911C

76

HLT

 

Program 2:

 

Read a key:

 

AIM:

 

To read a key and store the key code in memory location 9200. This code will be entered into the FIFO whenever a key is pressed. To read a key, procedure to be followed is,

1) Read the status word

2) Check for a key closure:

This can be done by checking the least significant 3 bits of the status word. If it zero, it means there is no key closure, so keep checking again.

3) If a key closure is encountered, read the data from FIFO RAM, and store this data (key code) in memory location 9200

The following program waits for a key to be pressed in the keyboard, reads the same and stores it in the location 9200

 

ADDRESS

OPCODE

MNEMONICS

9150

DB 62

LOOP: IN CNT

9152

E6 07

ANI 07

9154

CA 50 91

JZ LOOP

9157

3E 40

MVI A,40H

9159

D3 62

OUT CNT

915B

DB 60

IN DAT

915D

32 00 92

STA 9200

9160

76

HLT

 

Program 3:

Rolling display:

AIM:

To display the rolling message 'HELP US' in the display. The initialization of 8279 is same as that of Example-1. Then, the data is fetched from address 9200CH and displayed in the first digit of the display. The next data is displayed in the second Digit of the display, since in the command word for 'write display RAM' the Auto Increment flag is set. A time delay is given between successive digits for a lively display

 

ADDRESS

OPCODE

MNEMONICS

9100

21 2C 92

LXI H,9200H

9103

16 0F

MVI D,0FH

9105

3E 10

MVI A,10H

9107

D3 62

OUT CNT

9109

3E CC

MVI A,0CCH

910B

D3 62

OUT CNT

910c

3E 90

MVI A,90H

910F

D3 62

OUT CNT

9111

7E

LOP: MOV A,M

9112

D3 60

OUT DAT

9114

CD 1F 91

CALL DELAY

9117

23

INX H

9118

15

DCR D

9119

C2 11 91

JNZ LOP

911C

C3 00 91

JMP START

911F

06

DELAY: MVI B,0A0H

9121

0E FF

LOP1: MVI C,0FFH

9123

0D

LOP2: DCR C

9124

C2 23 91

JNZ LOP 2

9127

05

DCR B

9128

C2 21 91

JNZ LOP1

912B

C9

RET

 

Look-Up Table:-

9200 FFH FFH FFH FFH

9204 FFH FFH FFH FFH

9208 98H 68H 7CH C8H

920C FFH ICH 29H FFH

Program 4:

Accept a key and display it:

AIM:

To accept a key from the Hex keyboard and display it in the display. The initialization of 8279's FIFO RAM and DISPLAY RAM are the same as that given in example 3. A lookup table is provided to obtain the corresponding display codes for the keys

 

ADDRESS

style="margin-bottom: 10pt; text-align: center;">OPCODE

MNEMONICS

9100

06 08

MVI B,08

9102

3E 00

MVI A,00H

9104

D3 62

OUT CNT

9106

3E CC

MVI A,0CCH

9108

D3 62

OUT CNT

910A

3E 90

MVI A,90H

910C

D3 62

OUT CNT

910E

3E FF

MVI A,0FFH

9110

D3 60

BACK: OUT DAT

9112

05

DCR B

9113

C2 10 91

JNZ BACK

9116

DB 62

LOOP: IN CNT

9118

E6 07

ANI 07H

911A

CA 16 91

JZ LOP

911D

3E 40

MVI A,040H

911F

D3 62

OUT CNT

9121

DB 60

IN DAT

9123

E6 0F

ANI 0F

9125

4 6F

MOV L,A

9126

26 92

MVI H,92

9128

7E

MOV A,M

9129

D3 60

OUT DAT

912B

C3 16 91

JMP LOOP

 

Look-Up Table:-

9200 0CH 9FH 4AH 0BH

9204 99H 29H 28H 8FH

9208 08H 09H 88H 38H

920C 6CH 1AH 68H E8H

b) 8279 Interface With 8051

8051 Micro Processor on Board I/O Decoding Address

 

CONTROL

ADDRESS

Control REG

40A2H

Control Data

40A0H

 

Display data "a":

AIM:

To initialize 8279 and to display the character "A" in the first digit of the display. However, before sending codes to the display RAM, a write display RAM control word should be sent. Then, write the data to be displayed, to the data register.

 

ADDRESS

OPCODE

MNEMONICS

9100

90 40 A2

MOV DPTR,#40A2

9103

74 00

MOV A,#00

9105

F0

MOVX @DPTR,A

9106

74 CC

MOV A,#CC

9108

F0

MOVX @DPTR,A

9109

74 90

MOV A,#90

910B

F0

MOVX @DPTR,A

910C

90 40 A0

MOV DPTR,#40A0

910F

74 88

MOV A,#88

9111

F0

MOVX @DPTR,A

9112

78 05

MOV R0,#05

9114

74 FF

MOV A,#FF

9116

F0

LOOP: MOVX @DPTR,A

9117

D8 FD

DJNZ R0,LOOP

9119

80 FE

HERE: SJMP HERE

 

Program 2:

Read a key:

AIM:

To read a key and store the key code in memory location 9200. This code will be entered into the FIFO whenever a key is pressed. To read a key, procedure to be followed is,

1) Read the status word

2) Check for a key closure:

This can be done by checking the least significant 3 bits of the status word. If it zero, it means there is no key closure, so keep checking again.

3) If a key closure is encountered, read the data from FIFO RAM, and store this data (key code) in memory location 9200

The following program waits for a key to be pressed in the keyboard, reads the same and stores it in the location 9200

 

ADDRESS

OPCODE

MNEMONICS

9100

90 40 A2

MOV DPTR,#40A2

9103

E0

WAIT: MOVX A,@DPTR

9104

54 07

ANL A,#07

9106

60 FB

JZ WAIT

9108

74 40

MOV A,#40

910A

F0

MOVX @DPTR,A

910B

90 40 A0

MOV DPTR,#40A0

910E

E0

MOVX A,@DPTR

910F

90 86 00

MOV DPTR,#9200

9112

F0

MOVX @DPTR,A

9113

80 FE

HERE: SJMP HERE

 

Program 3:

Rolling display:

AIM:

To display the rolling message 'HELP US' in the display. The initialization of 8279 is same as that of Example-1. Then, the data is fetched from address 9200CH and displayed in the first digit of the display. The next data is displayed in the second Digit of the display, since in the command word for 'write display RAM' the Auto Increment flag is set. A time delay is given between successive digits for a lively display

 

ADDRESS

OPCODE

MNEMONICS

9100

90 40 A2

START: MOV DPTR,#40A2

9103

78 00

MOV R0,#00

9105

79 92

MOV R1,#92 : to initialize

9107

74 10

MOV A,#10 : look-up table

9109

F0

MOVX @DPTR,A : at 8700

910A

74 CC

MOV A,#CC

910C

F0

MOVX @DPTR,A

910D

74 90

MOV A,#90

910F

F0

MOVX @DPTR,A

9110

89 83

LOOP: MOV DPH,R1

9112

88 82

MOV DPL,R0

9114

E0

MOVX A,@DPTR

9115

90 40 A0

MOV DPTR,#40A0

9118

F0

MOVX @DPTR,A

9119

12 86 00

LCALL DELAY

911C

08

INC R0

911D

B8 0F F0

CJNE R0,#0F,LOOP

9120

02 91 00

LJMP START

8600

7C A0

DELAY: MOV R4,#A0

8602

7D FF

LOOP2 : MOV R5,#FF

8604

00

LOOP1 : NOP

8605

DD FD

DJNZ R5,LOOP1

8607

DC F9

DJNZ R4,LOOP2

8609

22

RET

 

Look-Up Table:-

9200 FFH FFH FFH FFH

9204 FFH FFH FFH FFH

9208 98H 68H 7CH C8H

920C FFH 1CH 29H FFH

Program 4:

Accept a key and display it:

AIM:

To accept a key from the Hex keyboard and display it in the display. The initialization of 8279's FIFO RAM and DISPLAY RAM are the same as that given in example 3. A lookup table is provided to obtain the corresponding display codes for the keys

 

ADDRESS

OPCODE

MNEMONICS

9100

79 86

MOV R1,#92

9102

78 08

MOV R0,#08

9104

90 40 A2

MOV DPTR,#40A2

9107

74 00

MOV A,#00

9109

F0

MOVX @DPTR,A

910A

74 CC

MOV A,#CC

910C

F0

MOVX @DPTR,A

910D

74 90

MOV A,#90

910F

F0

MOVX @DPTR,A

9110

74 40

MOV A,#FF

9112

90 40 A0

MOV DPTR,#40A0

9115

F0

LOOP: MOVX @DPTR,A

9116

D8 FD

DJNZ R0,LOOP

9118

90 40 A2

AGAIN: MOV DPTR,#40A2

911B

E0

WAIT: MOVX A,@DPTR

911C

54 07

ANL A,#07

911E

60 FB

JZ WAIT

9120

74 40

MOV A,#40

9122

F0

MOVX @DPTR,A

9123

90 40 A0

MOV DPTR,#40A0

9126

E0

MOVX A,@DPTR

9127

54 0F

ANL A,#0F

9129

F5 82

MOV DPL,A

912B

89 83

MOV DPH,R1

912D

E0

MOVX A,@DPTR

912E

90 40 A0

MOV DPTR,#40A0

9131

F0

MOVX @DPTR,A

9132

80 E4

SJMP AGAIN

 

Look-Up Table:-

9200 0CH 9FH 4AH 0BH

9204 99H 29H 28H 8FH

9208 08H 09H 88H 38H

920C 6CH 1AH 68H E8H

c) 8229 Interface With 8086

8086 Micro Processor on Board I/O Decoding Address

 

CONTROL

ADDRESS

Control REG

40A2H

Control Data

40A0H

 

Program 1:

Display data "A":

AIM:

To initialize 8279 and to display the character "A" in the first digit of the display. However, before sending codes to the display RAM, a write display RAM control word should be sent. Then, write the data to be displayed, to the data register.

 

ADDRESS

OPCODE

MNEMONICS

1100

BA 52 FF

START:MOV DX,FF52

1103

B0 00

MOV AL,00

1105

EE

OUT DX,AL

1106

B0 CC

MOV AL,CC

1108

EE

OUT DX,AL

1109

B0 90

MOV AL,90

110B

BA 50 FF

MOV DX,FF50

110E

B0 88

MOV AL,88

1110

EE

OUT DX,AL

1111

B0 FF

MOV AL,FF

1113

B9 05 00

MOV CX,0005

1116

EE

LP1: OUT DX,AL

1117

E2 FD

LOOP LP1

1119

EB E5

JMP START

 

Program 2:

Read a key:

AIM:

To read a key and store the key code in memory location 1200. This code will be entered into the FIFO whenever a key is pressed. To read a key, procedure to be followed is,

1) Read the status word

2) Check for a key closure:

This can be done by checking the least significant 3 bits of the status word. If it zero, it means there is no key closure, so keep checking again.

3) If a key closure is encountered, read the data from FIFO RAM, and store this data (key code) in memory location 1200

The following program waits for a key to be pressed in the keyboard, reads the same and stores it in the location 1200

 

ADDRESS

OPCODE

MNEMONICS

1100

BB 00 12

MOV BX,1200

1103

BA 52 FF

MOV DX,FF52

1106

EC

LOP1: IN AL,DX

1107

A8 07

TEST AL,07

1109

74 FB

JZ L0P1

110B

B0 40

MOV AL,40

110D

BA 52 FF

MOV DX,FF52

1110

EE

OUT DX,AL

1111

BA 50 FF

MOV DX,FF50

1114

EC

IN AL,DX

1115

88 07

MOV [BX],AL

1117

F4

HLT

 

Program 3:

Rolling display:

AIM:

To display the rolling message 'HELP US' in the display. The initialization of 8279 is same as that of Example-1. Then, the data is fetched from address 1200CH and displayed in the first digit of the display. The next data is displayed in the second Digit of the display, since in the command word for 'write display RAM' the Auto Increment flag is set. A time delay is given between successive digits for a lively display

 

ADDRESS

OPCODE

MNEMONICS

1100

BE 00 12

START:MOV SI,1200

1103

B9 0F 00

MOV CX,000F

1106

B0 10

MOV AL,10

1108

BA 52 FF

MOV DX,FF52

110B

EE

OUT DX,AL

110C

B0 CC

MOV AL,CC

110E

EE

OUT DX,AL

110F

B0 90

MOV AL,90

1111

EE

OUT DX,AL

1112

8A 04

LOP1: MOV AL,[SI]

1114

BA 50 FF

MOV DX,FF50

1117

EE

OUT DX,AL

1118

E8 E5 01

CALL 1300

111B

46

INC SI

111C

E2 F4

LOOP LOP1

111E

EB E0

JMP START

1300

BA FF A0

DELAY:MOV DX,A0FF

1303

4A

DEC DX

1304

75 FD

JNZ 1303

1306

C3

RET

 

Look-Up Table:-

1200 FFH FFH FFH FFH

1204 FFH FFH FFH FFH

1208 98H 68H 7CH C8H

120C FFH 1CH 29H FFH