I'm working with a PIC2455, trying to get it to send a byte on the EUSART every few milliseconds.
What is happening is I get a constant pulse train out, rather than
9bits-pause-9bits. I know the timer is working by scoping the A1 pin. I thought it was because I was sending 0x55 at first, but I still get a pulse train even when loading 0x00 into TXREG.
It's reassurring that I'm getting something other than a flatline, but still...
What am I overlooking?
#include
config LVP = OFF config XINST = OFF config CPUDIV = OSC1_PLL2 config PLLDIV = 12 ;12 config WDT = OFF config MCLRE = OFF config DEBUG = OFF config PBADEN = ON config LPT1OSC = OFF config FOSC = INTOSCIO_EC
cblock 0x20 TimerVal RESULTHI RESULTLO endc
org 0 goto Start
Start
movlw 0x09 ;'00001001' movwf TRISA ; BSF TRISA,0 ;Set RA0 to ADC input ; BCF TRISA,1 ;Set RA1 to output ; bsf TRISA,3 ;set A3 for input - pushbutton
movlw 0xFF ; make PORTB all input movwf TRISB
;setup PORTC for EUSART out CLRF TRISC BSF TRISC, 6
;setup ADC clrf ADCON0 movlw 0x0E movwf ADCON1 movlw 0xAF movwf ADCON2
;set timer1 for 2ms operation clrf T1CON clrf TMR1H
;set EUSART for Transmit movlw b'11110111' ;SENDB=0 movwf TXSTA
clrf SPBRGH movlw 0x01 ;set baud control register for 117.6k movwf SPBRG ; pg. 244, 4MHz
clrf BAUDCON bsf BAUDCON, BRG16 ;baud rate bit=high
movlw 0x90 movwf RCSTA
; more timer stuff movlw 0x00 ;set timer interval movwf TimerVal
; activate timer movwf TMR1L movlw b'10000001' movwf T1CON
TransmitLoop BTFSS PIR1, TMR1IF ; wait for timer to go off goto $-2 setf TMR1H decf TMR1H movf TimerVal, w movwf TMR1L ;reset timer for next countdown bcf PIR1, TMR1IF
; pulse to trigger scope BSF PORTA, 1 ; BCF PORTA, 1
movlw 0x00;55 btfsc RESULTHI, 3 movlw 0x00
BSF TXSTA, TX9D ;set/clear 9th bit before updating TXREG! movwf TXREG goto TransmitLoop end