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Search: Search by Price Search Between: $ &	3X4 Diode Matrix Keypad This information is based on works by Mike Rigby-Jones. I have rewritten the code just a little to allow a better understanding of code writing for the beginner. This routine proves invaluable when I/O pins are in short supply. I see no reason why this same technique of scanning cannot be used on most any micro. Care should be taken when using it with another micro. The PIC 16F84 has weak pullup resistors allowing this program to scan as it is written. This is also compatible with the 16F628. This code may need some work. This is a piece of code from a larger project. As with any code from the internet, test it completely before using!!!! We provide this code as an example. It is written so it is obvious to see the flow of the code. ***** CODE BEGINS CUT HERE ***** Filename: Keypdex.asm Date: 11-28-02 File Version:1.1 Author: N8HKI Company: Shultz Electronics Files Required: p16f628.inc LIST P=16F84 ; LIST DIRECTIVE TO DEFINE PROCESSOR #INCLUDE <P16F84.INC> ; PROCESSOR SPECIFIC VARIABLE DEFINITIONS __CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _RC_OSC ; '__CONFIG' DIRECTIVE IS USED TO EMBED CONFIGURATION DATA WITHIN .ASM FILE. ; THE LABLES FOLLOWING THE DIRECTIVE ARE LOCATED IN THE RESPECTIVE .INC FILE. ; SEE RESPECTIVE DATA SHEET FOR ADDITIONAL INFORMATION ON CONFIGURATION WORD. ;***** VARIABLE DEFINITIONS W_TEMP EQU 0X0C ; VARIABLE USED FOR CONTEXT SAVING STATUS_TEMP EQU 0X0D ; VARIABLE USED FOR CONTEXT SAVING KEY EQU 0X0E ;You may find variables that are not in use!!!!! CODENO EQU 0X11 DIGONE EQU 0X12 DIGTWO EQU 0X13 DIGTHREE EQU 0X14 DIGFOUR EQU 0X15 KEYNO EQU 0X16 SHIFT EQU 0X17 COUNT EQU 0X18 CNTA EQU 0X19 CNTB EQU 0X1A PINONE EQU 0X1B PINTWO EQU 0X1C PINTHREE EQU 0X1D PINFOUR EQU 0X1E ;********************************************************************** ORG 0X000 ; PROCESSOR RESET VECTOR GOTO SETUP ; GO TO BEGINNING OF PROGRAM ORG 0X004 ; INTERRUPT VECTOR LOCATION MOVWF W_TEMP ; SAVE OFF CURRENT W REGISTER CONTENTS MOVF STATUS,W ; MOVE STATUS REGISTER INTO W REGISTER MOVWF STATUS_TEMP ; SAVE OFF CONTENTS OF STATUS REGISTER ; ISR CODE CAN GO HERE OR BE LOCATED AS A CALL SUBROUTINE ELSEWHERE MOVF STATUS_TEMP,W ; RETRIEVE COPY OF STATUS REGISTER MOVWF STATUS ; RESTORE PRE-ISR STATUS REGISTER CONTENTS SWAPF W_TEMP,F SWAPF W_TEMP,W ; RESTORE PRE-ISR W REGISTER CONTENTS RETFIE ; RETURN FROM INTERRUPT SETUP CLRF PORTA CLRF PORTB MOVLW B'00000000' TRIS PORTB MOVLW B'11111111' TRIS PORTA MOVLW 0X00 MOVWF COUNT CALL DELAY BSF PORTB,7 ;PIEZO BEEPER ON AND OFF CALL DELAY BCF PORTB,7 CALL DELAY BSF PORTB,7 CALL DELAY BCF PORTB,7 CALL DELAY MOVLW D'1' ;SET FIRST DIG. OF CODE HERE PUNCH IN 1,2,3,4 TO GET GOODCHECK MOVWF PINONE MOVLW D'2' ;SET SECOND DIG. MOVWF PINTWO MOVLW D'3' ;SET THIRD DIG MOVWF PINTHREE MOVLW D'4' ;SET FOURTH DIG MOVWF PINFOUR GOTO MAIN TABLEONE ADDWF PCL,F RETLW 0XFF ;FAKE SHOULD NEVER GET HERE!!! RETLW 0X0B RETLW 0X0A RETLW 0X00 TABLETWO ADDWF PCL,F RETLW 0X08 RETLW 0XFF ;FAKE SHOULD NEVER GET HERE!!! RETLW 0X07 RETLW 0X09 TABLETHREE ADDWF PCL,F RETLW 0X05 RETLW 0X06 RETLW 0XFF ;FAKE SHOULD NEVER GET HERE!!! RETLW 0X04 TABLEFOUR ADDWF PCL,F RETLW 0X02 RETLW 0X03 RETLW 0X01 VERIFY MOVF DIGONE,W SUBWF PINONE,W BTFSS STATUS,Z GOTO CHECKBAD MOVF DIGTWO,W SUBWF PINTWO,W BTFSS STATUS,Z GOTO CHECKBAD MOVF DIGTHREE,W SUBWF PINTHREE,W BTFSS STATUS,Z GOTO CHECKBAD MOVF DIGFOUR,W SUBWF PINFOUR,W BTFSS STATUS,Z GOTO CHECKBAD GOTO GOODCHECK MAIN ;PLACE CODE TO DO OTHER THINGS HERE! GOTO SCAN SCAN MOVLW B'00100000' ;SCAN BUTTON ROW1 *,0,# TRIS PORTB MOVLW B'11111110' TRIS PORTA BCF PORTA,0 MOVF PORTA,W MOVWF KEY SUBLW B'00011110' ;TESTING TO SEE IF BUTTON HAS BEEN PRESSED IN THE ROW BTFSS STATUS,Z GOTO OFFONE GOTO ROWTWO OFFONE CALL DELAY LOOPONE MOVF PORTA,W ;THIS LOOP IS WAITING FOR THE BUTTON TO BE RELEASED SUBLW B'00011110' BTFSS STATUS,Z GOTO LOOPONE CALL CALC MOVF SHIFT,W CALL TABLEONE MOVWF KEY GOTO KEYLOAD ROWTWO BSF PORTA,0 ;SCAN BUTTON ROW2 7,8,9 MOVLW B'11111101' TRIS PORTA BCF PORTA,1 MOVF PORTA,W MOVWF KEY SUBLW B'00011101' BTFSS STATUS,Z GOTO OFFTWO GOTO ROWTHREE OFFTWO CALL DELAY LOOPTWO MOVF PORTA,W SUBLW B'00011101' BTFSS STATUS,Z GOTO LOOPTWO CALL CALC MOVF SHIFT,W CALL TABLETWO MOVWF KEY GOTO KEYLOAD ROWTHREE BSF PORTA,1 ;SCAN BUTTON ROW 4,5,6 MOVLW B'11111011' TRIS PORTA BCF PORTA,2 MOVF PORTA,W MOVWF KEY SUBLW B'00011011' BTFSS STATUS,Z GOTO OFFTHREE GOTO ROWFOUR OFFTHREE CALL DELAY LOOPTHREE MOVF PORTA,W SUBLW B'00011011' BTFSS STATUS,Z GOTO LOOPTHREE CALL CALC MOVF SHIFT,W CALL TABLETHREE MOVWF KEY GOTO KEYLOAD ROWFOUR BSF PORTA,2 ;SCAN BUTTON ROW 1,2,3 MOVLW B'11110111' TRIS PORTA BCF PORTA,3 MOVF PORTA,W MOVWF KEY SUBLW B'00010111' BTFSS STATUS,Z GOTO OFFFOUR GOTO MAIN OFFFOUR CALL DELAY LOOPFOUR MOVF PORTA,W ;THIS LOOP IS WAITING FOR THE BUTTON TO BE RELEASED SUBLW B'00010111' BTFSS STATUS,Z GOTO LOOPFOUR CALL CALC MOVF SHIFT,W CALL TABLEFOUR MOVWF KEY GOTO KEYLOAD KEYLOAD INCF COUNT,1 MOVF COUNT,W SUBLW 0X01 BTFSC STATUS,Z GOTO LOADONE MOVF COUNT,W SUBLW 0X02 BTFSC STATUS,Z GOTO LOADTWO MOVF COUNT,W SUBLW 0X03 BTFSC STATUS,Z GOTO LOADTHREE MOVF COUNT,W SUBLW 0X04 BTFSC STATUS,Z GOTO LOADFOUR GOTO CHECKBAD LOADONE MOVF KEY,W MOVWF DIGONE MOVWF PORTB BSF PORTB,7 CALL DELAY BCF PORTB,7 GOTO MAIN LOADTWO MOVF KEY,W MOVWF DIGTWO MOVWF PORTB BSF PORTB,7 CALL DELAY BCF PORTB,7 GOTO MAIN LOADTHREE MOVF KEY,W MOVWF DIGTHREE MOVWF PORTB BSF PORTB,7 CALL DELAY BCF PORTB,7 GOTO MAIN LOADFOUR MOVF KEY,W MOVWF DIGFOUR MOVWF PORTB BSF PORTB,7 CALL DELAY BCF PORTB,7 MOVLW 0X00 MOVWF COUNT GOTO VERIFY CALC CLRF SHIFT LOOP BTFSC KEY,0 RETURN INCF SHIFT,1 RRF KEY,1 GOTO LOOP GOODCHECK BSF PORTB,7 CALL DELAY CALL DELAY CALL DELAY CALL DELAY BCF PORTB,7 GOTO MAIN DELAY MOVLW 0XFF MOVWF CNTA LOOPY MOVLW 0XFF MOVWF CNTB DEC DECFSZ CNTB GOTO DEC DECFSZ CNTA GOTO LOOPY RETURN CHECKBAD BSF PORTB,7 CALL DELAY CALL DELAY BCF PORTB,7 CALL DELAY CALL DELAY BSF PORTB,7 CALL DELAY CALL DELAY BCF PORTB,7 CALL DELAY CALL DELAY BSF PORTB,7 CALL DELAY CALL DELAY BCF PORTB,7 GOTO MAIN END Schematic of diode matrix for keypad. Diodes are 1N4148 We receive many requests to assist students and others with their code. We do try to provide help but can only do so as time allows. Click the "ASK A QUESTION" button above. SHULTZ ELECTRONICS 58 Smokey Crest Dr. Morgantown, WV 26508 PHONE: 1-888-474-8589 email: sales@shultzie.com	Featured Product VHF Marine Band Antenna Model 1600 No ground plane design. $ 24.95
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