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8279keypadN.pptx
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- 7. 3/23/2023 7 4 4 4 8 DATA BUS CLK RESET DB0-7 RD WR CS A0 IRQ RL0-7 SHIFT CNT/STB SL0-3 OUTA0-3 OUT B0-3 DB 8279 TO KEYPAD TO DISPLAY CPU INTERFACE
- 8. 3/23/2023 8 CLK RESETDB0-7 OUT A0-3 OUT B0-3 BD RD WR CS A0 IRQ SL0-3 RL0-7 SHIFT CNT/STB DATA BUFFERS I/O CONTROL FIFO SENSOR RAM DISPLAY ADDRESS REG 16X8 DISPLAY RAM CONTROL & TIMING REG 8X8 FIFO/SENSOR RAM KEYBOARD DEBOUNCE & CONTROL DISPLAY REG TIMING & CONTROL SCAN COUNTER RETURN 8 4 8
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- 13. 3/23/2023 13 Decoded Mode: Internal Decoder Encoded Mode : External Decoder SL0 0 SL1 1 SL2 1 SL3 1 1 0 1 1 1 1 0 1 1 1 1 0 SL0 0 SL1 0 SL2 0 1 0 0 0 1 0 1 1 0 0 1 2 3 CH. 0 0 1 4 1 0 1 5 0 1 1 6 1 1 1 7
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- 16. 3 SL0 SL1 SL3 SL2 OA0 OA1 OA2 OA3 OB0 OB1 OB2 OB3 RL0 RL1 RL2 RL3 RL4 RL5 RL6 RL7 IRQ BD SHFT CN/ST 0 0 0 0 1 1 0 11 1 1 1 1 1 0 7 6 5 4 3 2 1 0 0 0 0 0 0 0 x x RL0 RL1 RL2 SL0 SL1 SL2 CNT SHFT 1 D E F . , + : REG 2 3 4 5 6 7 - 8 9 B C A 7 6 5 4 3 2 1 0 1 0 1 0 0 0 x x RL0 RL1 RL2 SL0 SL1 SL2 CNT SHFT 0 0 0 0 1 1 1 1 1 1 1 0 1 1 1 0 0 1 0 1 1 0 1 1 1 1 1 1 7 6 5 4 2 1 0 1 0 0 0 0 0 0 RL0 RL1 RL2 SL0 SL1 SL2 CNT SHFT 74LS145 0 7 6 5 4 3 2 1 IC34 C B A DB0 DB1 DB2 DB3 DB0 DB6 DB4 DB5 RD WR CS CLK RESET A0 AD0-AD7 /RD /WR 8279 PCLK RESET A1 8279 IC30 1 Scanned keypad Register 3/23/2023 16 Scan Code
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- 18. Mode Command (Mode Selection) 00 0 D D K K K Keyboard Mode 0 0 0 Encoded Scan, 2 key lockout 0 0 1 Decoded Scan, 2 key lockout 0 1 0 Encoded Scan, N key Rollover 0 1 1 Decoded Scan, N key Rollover 1 0 0 Encoded Scan Sensor Matrix 1 0 1 Decoded Scan Sensor Matrix 1 1 0 Strobed Input,Encoded Display Scan 1 1 0 Strobed Input,Decoded Display Scan A0=1 D0 D7 D6 D5 D4 D3 D2 D1 3/23/2023 18
- 19. 0 0 1P P P P P A0=1 D0 D7 D6 D5 D4 D3 D2 D1 Divide the internal clock by PPPPP to get the basic internal frequency 2.5 MHz / ? = 100 KHz. 1 1 0 0 1 Clock Command (Scan Rate Selection) 25D 19h 3/23/2023 19
- 20. 3/23/2023 20 Read FIFOCommand (Write) 0 1 0 AI X A A A A0=1 D0 D7 D6 D5 D4 D3 D2 D1 Auto Increment Select the desired FIFO location
- 21. FIFO Status Register (Read) DS/E O U F N N N D0 D7 D6 D5 D4 D3 D2 D1 Number of Characters in FIFO FIFO Full Error– Underrun Error - Overrun Sensor Closure/Error Flag for Multiple Closure Display Unavailable 3/23/2023 21 A0=0
- 22. 3/23/2023 22 MOV DX,5002h;CW Address MOV AL,0 OUT DX,AL MOV AL,39h ;Clock Command OUT DX,AL CONT: MOV DX,5002h ;FIFO Status Add. IN AL,DX AND AL,07h JZ CONT MOV DX,5000h ;Scan Code Buffer IN AL,DX MOV SCODE,AL JMP CONT
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- 24. 3/23/2023 24 3 7 65 4 3 2 1 0 0 0 0 0 0 0 x x 7 6 5 4 3 2 1 0 1 0 1 0 x x 7 6 4 2 1 0 RL0 A0=0 RL1 RL2 RL3 RL4 RL5 RL6 RL7
- 25. 1. Draw theaddress decoder for an 8086 Microprocessor system having a 4x4 keypad matrix using 8279 controller putting the control word address = 3006h using: discrete components. 74138 decoder. 2. Write a program to initialize the controller then read keypad states and save it continuously in the memory. 3. Add a PPI with LEDs and a 7-Seg with start address=5000h, and display the key-N0. on both .
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