PIC16F877 serial program

[Erwin_Macaraig]

I am programming a PIC16F877 serial port. I am trying to send to the serial port the character 'e'. I am using hyperterminal to view the said character. I use 9600 baud rate, one stop bit,no parity and no hardware control settings. But the character I am trying to send to the hyperterminal does not seem to appear, mostly the its just a series of 1's and s.

here is my code. Your comments and suggestiions will be appreciated! Thank you in advance!!!



;source code(firmaware fragment) for the PIC16F877 serial communications



#include "P16f877.inc"



__config _wdt_off & _pwrte_on & _xt_osc & _boden_on & _wrt_enable_on & _lvp_off & _cpd_off





errorlevel -302



#define transmitEnable portc,5





cblock h'20'

temp

char

endc



org h'0000'



init

bcf STATUS,RP1

bsf STATUS,RP0 ;selects bank1

movlw b'10000000'

movwf TRISC ;makes pin7<RX> of portC input



movlw b'1000000' ;Fosc = 12Mhz

movwf SPBRG ;9600 baud rate hispeed



bsf TXSTA,BRGH ;bit2: High speed

bcf TXSTA,SYNC ;bit4: Asynchronous mode

bcf TXSTA,TX9 ;bit6: 8-Bit Transmit Enable bit



bcf PIE1,TXIE ;bit4: USART transmit Interrupt Enable bit

bsf TXSTA,TXEN ;bit5: Transmit enable bit



bcf STATUS,RP0 ;selects bank0

movlw b'10010000'

movwf RCSTA ;bit7: Serial Port Enable bit

bsf transmitEnable



main

call message_one

goto main







message_one

movlw d'101'

call sendit



call delay

call delay

call delay



return




sendit



btfss PIR1,TXIF ;poll bit4: Transmit Interrupt Flag

goto sendit

movwf TXREG


return




delay

movlw d'255'

movwf char

movwf temp



delayloop

decfsz char

goto delayloop

decfsz temp

goto delayloop

return





end

 

[motion]

Looking at your code, your baud rate setting may be incorrect. Assuming you're using a 12Mhz crystal as comments in your code suggest, the value of b'1000000' or 40h for SPBRG is wrong.

With BRGH=1, the correct value for 9600baud @ 12Mhz is D'77'.

 

[Nigel Goodwin]

You might also try my tutorials, I have an RS232 one which includes the 16F876/7 - but using a 20MHz clock - as motion says, you would have to make changes for your clock speed.

 

[Erwin_Macaraig]

thank you guys. But do you think that the remaining code are ok?