Help with pic16f684 adc

[slimjims]

It's been awhile since I've attempted any assembly programming, and I always remember having lots of trouble debugging. Anyways I'm to get back into it, I'm trying to read voltage values from a photo-resistor. Everything seems to work fine except the only values that are returned are 0x01 and 0x61. I can't figure out what might be causing the problem everything seems to be exactly how it should be.

;	
LIST R=DEC
LIST P=16f684
INCLUDE p16f684.inc
INCLUDE macros.inc
 __CONFIG _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _CPD_OFF & _CP_OFF & _MCLRE_ON & _PWRTE_ON & _WDT_OFF & _INTOSCIO


 PAGE
 org    0
;Configure EEPROM
 bcf	STATUS, 5
 bcf	INTCON, GIE		; disable interrupts

 bank1
 clrf	EEADR
 clrf	EEDAT
;Configure ADC
 movlw	7
 movwf	CMCON0			; turn off comparator

 bsf	TRISA, 0		; set RA0 to input
 bsf	ANSEL, 0		; set ANS0 to analog input
 movlw	01010000b
 movwf	ADCON1			; clock set to Fosc/16

 bcf	STATUS, 5
 movlw	00000001b		;configure ADCON0
 movwf	ADCON0		
;Start process
;wait 8uS, maximum required aquisition time
;In this example I'm gonna use it to do any 
; eeprom maintennance. In this case write eedat to eeprom
 pauc	1
main: 
 bcf	STATUS, 5
 bsf	ADCON0, GO		; begin conversion
 btfsc	ADCON0, GO
 goto	$-1			; wait for completion
 movf	ADRESH, 1
 bank1
 movwf	EEDAT 




 bsf	STATUS, 5
 bsf	EECON1, WREN
 movlw	0x55
 movwf	EECON2
 movlw	0xAA
 movwf	EECON2
 bsf	EECON1, WR		; write begins

 btfsc	EECON1, WR
 goto	$-1			;wait for write to end
 nop
 nop
 incf	EEADR, 1
 bcf	STATUS, 5
 bcf	PIR1, EEIF
;back to ADC stuff


 tenth	8
 goto	main

end

 

[upand_at_them]

First, checking your banking. CMCON0 is not in bank 1.

 

[slimjims]

Thanks for the response, I'm not sure how I missed that. :-? But after tweaking different values (clock speed, delays, etc.) I'm still at a total loss as to what could be preventing this from working. I've cleaned up the code a little, and if anyone wants to take a shot at fixing it I'd appreciate it.

LIST R=DEC
LIST P=16f684
INCLUDE p16f684.inc
INCLUDE macros.inc
 __CONFIG _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _CPD_OFF & _CP_OFF & _MCLRE_ON & _PWRTE_ON & _WDT_OFF & _INTOSCIO

;  Variables
 CBLOCK 0x020
   count0
   count1
   count2
 ENDC


 PAGE
 org    0

eeprom_config:
 bank0
 bcf	INTCON, GIE		; disable interrupts
 bank1
 clrf	EEADR
 clrf	EEDAT


adc_config:
  bank0
  movlw	7
  movwf	CMCON0			; turn off comparator
  bank1
  movlw	01010000b
  movwf	ADCON1			; clock set to Fosc/16
  bsf	TRISA, 0		; set RA0 to input
  bsf	ANSEL, 0		; set ANS0 to analog input
  bank0
  movlw	00000001b		;configure ADCON0
  movwf	ADCON0		
  pauc	1                   ;delay macro  -  ten cycles


main:
  bsf	ADCON0, GO		; begin conversion
  btfsc	ADCON0, GO
  goto	$-1			; wait for completion
  movf	ADRESH, 1
  bank1
  movwf	EEDAT 

save:
  bsf	STATUS, 5
  bsf	EECON1, WREN
  movlw	0x55
  movwf	EECON2
  movlw	0xAA
  movwf	EECON2
  bsf	EECON1, WR		; write begins
  btfsc	EECON1, WR
  goto	$-1			;wait for write to end
  nop
  nop
  incf	EEADR, 1
  bcf	STATUS, 5
  bcf	PIR1, EEIF

 tenth	8                      ;delay macro   -   800 cycles
 goto	main

end

 

[upand_at_them]

You should use the proper mneumonics for assembly instructions. "movf ADRESH, 1" in particular isn't moving the value into the W register.

Mike

 

[sankar.m8]

Make port A as input (by entering values in TRISA)
movlw 7 .....you hav to specify whether it is hex,binary or digit movlw H'07' or movlw D'7' etc
use some delay instead of pauc 1

 

[slimjims]

Thanks, that was the problem. I must have misread the instruction set summary or something.

---------- Post added at 18:10 ---------- Previous post was at 18:08 ----------

and thanks for that suggestion sankar.

 

[upand_at_them]

Glad to help. Using "F" and "W" instead of "1" and "0" helps to alleviate problems.