Using an Assmbly Routine in PBP
Hi--
I'm trying to adapt Microchip's AN1076 appnote on DMX to use as an assembly language subroutine in PBP. I'm using a PIC18F4520, 16MHz resonator, PBP 2.5a. What the code should do is initialize the LCD, read the DMX data stream, and then display the value present on DMX channel 7 on the LCD. I am feeding in a DMX signal, and I've had a PBP-coded subroutine working just fine on my hardware test board, but I need more speed. Both the SetupSerial subroutine and the DMXloop subroutine compile just fine, but when I call the DMXloop subroutine, that's the last I see of my program's execution, nothing else happens. I assume I'm jumping off into oblivion somehow... my understanding of assembly is limited, so I'd appreciate any commentary.
Thanks in advance--
--Alan
Code:' for PIC18F4530 DEFINE OSC 16 INCLUDE "modedefs.bas" include "LCD_defines602.pbp" ' **************************************** ' SETUP ' **************************************** PORTA = %00000000 PORTB = %00000000 PORTC = %00000000 PORTD = %00000000 trisa = %11111101 trisb = %01111111 TRISC = %11101000 trisd = %11001011 ADCON1 = %00001111 'port a is all digital IO CMCON = 7 'and turn off those pesky comparators RBPUx VAR INTCON2.7 'port b pull-ups 1 = disabled 0 = enabled RBPUx = 0 trise.4 =%0 'disable PSP port ' =================================== ' define hardware pins: ' =================================== BKLT var portd.5 'LCD backlight ' ================================ ' define constants & variables: ' ================================ DMXrxbuffer var byte[512] CountH var byte CountL var byte count0 var byte ' **************************************** ' INITIALIZATION ' **************************************** init: call SetupSerial 'set up USART and clear DMXrxbuffer ' **************************************** ' MAIN LOOP ' **************************************** begin: low bklt 'turn on backlight pause 125 'pause to let LCD initialize lcdout $fe,1 'clear screen LCDout " test routine " 'display splashscreen lcdout $fe,$c0,"S/W Version 6xxx" pause 1200 low bklt mainloop: Call DMXloop lcdout $fe,1 pause 3 lcdout dec DMXrxbuffer[7] pause 300 goto mainloop asm _DMXloop ; first loop, synchronizing with the transmitter _WaitBreak btfsc PIR1,RCIF ; if a byte is received correctly movf RCREG,W ; discard it btfss RCSTA,FERR ; else bra _WaitBreak ; continue waiting until a frame error is detected movf RCREG,W ; read the Receive buffer to clear the error condition ; second loop, waiting for the START code _WaitForStart btfss PIR1,RCIF ; wait until a byte is correctly received bra _WaitForStart btfsc RCSTA,FERR bra _WaitForStart movf RCREG,W ; check for the START code value, if it is not 0, ignore the rest of the frame andlw 0xff bnz _DMXloop ; ignore the rest of the frame if not zero ; init receive counter and buffer pointer clrf _CountL clrf _CountH lfsr 0,_DMXrxbuffer ; third loop, receiving 512 bytes of data _WaitForData btfsc RCSTA,FERR ; if a new framing error is detected (error or short frame) bra _RXend ; the rest of the frame is ignored and a new synchronization ; is attempted btfss PIR1,RCIF ; wait until a byte is correctly received bra _WaitForData ; movf RCREG,W ; _MoveData movwf POSTINC0 ; move the received data to the buffer ; (auto-incrementing pointer) incf _CountL,F ; increment 16-bit counter btfss STATUS,C bra _WaitForData incf _CountH,F btfss _CountH,1 ; check if 512 bytes of data received bra _WaitForData _RXend return ;**************************************************************** ; Setup Serial port and buffers _SetupSerial ;Clear the receive buffer lfsr 0,_DMXrxbuffer _CBloop clrf POSTINC0 ; clear INDF register then increment pointer incf _CountL,F btfss STATUS,C bra _CBloop incf _CountH,F btfss _CountH,1 bra _CBloop ; Setup EUSART bsf TRISC,7 ; allow the EUSART RX to control pin RC7 bsf TRISC,6 ; allow the EUSART TX to control pin RC6 movlw 0x04 ; Disable transmission movwf TXSTA ; enable transmission and CLEAR high baud rate movlw 0x90 movwf RCSTA ; enable serial port and reception bsf BAUDCON,BRG16 ; Enable UART for 16-bit Asyn operation clrf SPBRGH movlw .15 ; Baud rate is 250KHz for 16MHz Osc. freq. movwf SPBRG return endasm
Originally Posted by alanmcf
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