Tony Nixon [sales at picnpoke.com] of ICmicro's says:
Title "Your Program" ; list P = 16F877 ; include "P16f877.inc" ; ; ------------------ ; CONFIGURATION FUSE ; ------------------ ; __CONFIG _CP_OFF & _WRT_ENABLE_ON & _RC_OSC & _WDT_ON & _PWRTE_OFF & _BODEN_ON & _LVP_ON & _CPD_OFF & _DEBUG_OFF ; ; CRYSTAL SPEED = 4000000Hz ; CBLOCK 0x20 dataL ENDC ; ; ------------- ; PROGRAM START ; ------------- ; org 0x0000 ; startup = 0000h ; Start movlw 0x00 ; setup ports movwf PORTA movlw 0x00 movwf PORTB movlw 0x40 movwf PORTC movlw 0x00 movwf PORTD movlw 0x00 movwf PORTE bsf STATUS,RP0 ; RAM Page 1 movlw 0x00 movwf TRISA movlw 0x00 movwf TRISB movlw 0x80 movwf TRISC movlw 0xFF movwf TRISD movlw 0xFF movwf TRISE ; ; ------------------------- ; SET ANALOG/DIGITAL INPUTS ; ------------------------- ; movlw 0x06 ; all digital movwf ADCON1 ; ; ------------------------------------ ; SET BAUD RATE TO COMMUNICATE WITH PC ; ------------------------------------ ; Boot Baud Rate = 19200, No Parity, 1 Stop Bit ; movlw 0x0C ; 19200 baud movwf SPBRG movlw b'00100100' ; brgh = high (2) movwf TXSTA ; enable Async Transmission, set brgh movlw b'10010000' ; enable Async Reception bcf STATUS,RP0 ; RAM Page 0 movwf RCSTA ; ; ------------------------------------ ; PROVIDE A SETTLING TIME FOR START UP ; ------------------------------------ ; clrf dataL settle decfsz dataL,F goto settle ; movf RCREG,W movf RCREG,W movf RCREG,W ; flush receive buffer Loop call Receive ; wait for a char movwf TXREG ; echo data back to sender goto Loop ; ; ---------------------------- ; RECEIVE CHARACTER FROM RS232 ; ---------------------------- ; This routine does not return until a character is received. ; Receive btfss PIR1,RCIF ; (5) check for received data goto Receive ; movf RCREG,W return ; ; ------------------------------------ ; WAIT UNTIL RS232 IS FINISHED SENDING ; ------------------------------------ ; TransWt bsf STATUS,RP0 WtHere btfss TXSTA,TRMT ; (1) transmission is complete if hi goto WtHere ; clrf STATUS ; RAM Page 0 return ; ; end
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