Heyas,

To get myself accustomed to mcu programming I am trying to set up a =
stoplight style program.
I am using the onboard USART and can get chars transmitted and received =
in hyperterminal. But I can't
get the LEDs I attached to PortB bits 0, 1, and 2 to light up.

Does the use of PortB as the serial comm port somehow make the other =
bits on that port unusable?

I've pasted my code below, I checked it a couple times for errors but =
it's hard to set up a good test because of the need to go through the =
USART. MPSIM doesn't have a way to set up stimulus files to do this =
afaik.

Thanks a bunch
=20
// =3D=3D=3D=3D=3D Code Below =3D=3D=3D=3D=3D
=20
; Hardware Notes: PIC16F876 @ 4Mhz
;
; _MCLR pulled up through 10k-ohm
; RC6 - Serial Transmit Pin
; RC7 - Serial Receive Pin
;
; v1.0

 LIST P=3D16F876, R=3DDEC
 INCLUDE "p16F876.inc"
=20
 CBLOCK 0x020            ; Var not used in this incarnation, was used =
previously to
 SerTemp                      ; store the serial value to work with all =
3 lights.
 ENDC
=20
 __CONFIG _CP_OFF & _HS_OSC & _PWRTE_ON & _WDT_OFF & _BODEN_ON
=20
; Mainline

 org 0
=20
 bcf PORTB, 0   ; PortB 0, off (Red)
 bcf PORTB, 1   ; PortB 1, off (Yellow)
 bcf PORTB, 2   ; PortB 2, off (Green)
=20
 bsf STATUS, RP0  ; Enable the Serial Port
 movlw (1 << TXEN)  ; Enable Serial Transmission
 movwf TXSTA ^ 0x080
 movlw 51    ; Serial Port running at 1200baud
 movwf SPBRG ^ 0x080
=20
 bsf TRISB ^ 0x080, 0 ; Set PortB 0.1.2 to output
 bsf TRISB ^ 0x080, 1
 bsf TRISB ^ 0x080, 2
=20
 bcf STATUS, RP0
 movlw (1 << SPEN) | (1 << CREN)
 movwf RCSTA   ; Enable Serial I/O
=20
Loop
 btfss PIR1, RCIF  ; Wait for rx character set
  goto Loop    ; Nothing there
 movf RCREG, 0   ; Get rx character
 bcf PIR1, RCIF   ; Clear the Character Present Flag
=20
 ; Check the rx char against R, Y, G to set indicators
 ;movwf SerTemp
 ;sublw 'R'
 ;BTFSS STATUS, Z
 ; call GORED
 ;movf SerTemp, 0
 ;movwf SerTemp
 ;sublw 'Y'
 ;BTFSS STATUS, Z
 ; call GOYEL
 ;movf SerTemp, 0
 ;movwf SerTemp
 ;sublw 'G'
 ;BTFSS STATUS, Z
 ; call GOGRN
 ;
=20
 bsf PORTB, 0        ; Can I set the bits on at all?
 bsf PORTB, 1
=20
 XORWF 'R', w
 BTFSS STATUS, Z
  ;call GORED        ; Didn't work this way, trying to set it explicitly =
below
  bsf PORTB, 0
=20
 movwf TXREG        ; Transmit char for error checking
=20
 goto Loop
=20
 ; Subroutines
GORED:
 bsf PORTB, 0
 bcf PORTB, 1
 bcf PORTB, 2
 goto Loop
 return
=20
GOYEL:
 bcf PORTB, 0
 bsf PORTB, 1
 bcf PORTB, 2
 goto Loop
 return
=20
GOGRN:
 bcf PORTB, 0
 bcf PORTB, 1
 bsf PORTB, 2
 goto Loop
 return

 end

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu