First of all, thanks for the previous help with this program to all who took the time. I would not bother you again with the same program, but I am stumped.

The program runs fine, outputs work. Not sure about the A/D working though. I had originally set up AN3 to get the delay value that is decremented. It was not working apparently, so I just put in a value in the code for "Delay".

The problem is that no matter what I set the value at, the delay I actually see on the LEDs is always the same, and only changes with the prescalar on Timer0. I tried changing the RAM address of "Delay" to 0x0022 from 0x0020, did not help. I am at a loss here. The program runs exactly as it should otherwise. The thing that puzzles me is that Delay is being decremented somewhere, as the program will not continue to the next LED until is is 0. Unless it never had a value to begin with and is always 0?

http://h1.ripway.com/AmbientSix/Strobe.txt

EDIT: I am not sure how to make the text file open in the post, when I just copied it the format was awful.

 

List p=12f683
include P12F683.INC
__CONFIG _FCMEN_ON & _IESO_OFF & _CP_OFF & _CPD_OFF & _BOD_OFF & _MCLRE_ON & _WDT_OFF & _PWRTE_OFF & _INTOSCIO &_INTRC_OSC_NOCLKOUT
errorlevel -302 ; suppress message 302 from list file

w_temp EQU 0x7E ; variable used for context saving
status_temp EQU 0x7F ; variable used for context saving
Delay EQU 0x0022
Done EQU 0x0021
red EQU b'00000001'
wht EQU b'00000010'
blue EQU b'00000100'

;*****************[code]***********************************
org 0x0000
goto INIT
NOP
NOP
NOP

org 0x0004
GOTO ISR

org 0x0005
INIT

BSF STATUS,RP0 ;selects memory Bank 1

MOVLW b'01000001'
MOVWF OSCCON ;sets oscillator to 1MHz

MOVLW b'00000000'
MOVWF OPTION_REG ;enables Timer0, 1:4 PS (1.024ms/overflow)

MOVLW b'10100000'
MOVWF INTCON ;enable GIE, Timer0 interrupt

MOVLW b'00000111'
MOVWF CMCON0 ;disables comparator

BCF STATUS,RP0 ;selects memory Bank 0
CLRF GPIO
BSF STATUS,RP0 ;Bank 1 selected

MOVLW b'00011000' ;GP0,1,2,5 as outputs, GP3,4 as inputs.
MOVWF TRISIO ;GP3,5 are for future add-ons.
MOVLW b'00010000' ;GP4 analog input enable, FOSC/2
MOVWF ANSEL

MOVLW b'10001101' ;right justify, VDD ref, AN0, ADON
MOVWF ADCON0
BCF STATUS,RP0 ;Bank 0 selected

MOVLW h'0009'
MOVWF Delay

START
CLRF TMR0
; BSF ADCON0,ADON
; BSF ADCON0,GO ;get A/D data for "Delay" variable
; BTFSC ADCON0,GO
; GOTO $-1
; MOVF ADRESL,W
; MOVWF Delay
; BCF ADCON0,ADON ;disables A/D till next use.


;==================RED=========================
RedON
BCF Done,h'0000'
MOVLW red
MOVWF GPIO ;turns red LED on.
BTFSC Done,h'0000' ;tests for decrementing complete
GOTO WhtON ;executed when complete
GOTO $-2 ;executed when not complete

;==================WHITE========================
WhtON
BCF Done,h'0000'
MOVLW wht
MOVWF GPIO ;turns white LED on.
BTFSC Done,h'0000'
GOTO BlueON
GOTO $-2

;==================BLUE=========================
BlueON
BCF Done,h'0000'
MOVLW blue
MOVWF GPIO ;turns blue LED on.
BTFSC Done,h'0000'
GOTO START
GOTO $-2

;*********************ISR************************
ISR
movwf w_temp ; save off current W register contents
movf STATUS,w ; move status register into W register
movwf status_temp ; save off contents of STATUS register
BCF INTCON,T0IF
DECFSZ Delay,F
GOTO CONTEXT ;If not done decrementing, returns to current loop
MOVLW h'0001'
MOVWF Done ;done decrementing, places h'1' in "Done" register
GOTO CONTEXT
CONTEXT
movf status_temp,w ;retrieve copy of STATUS register
movwf STATUS ; restore pre-isr STATUS register contents
swapf w_temp,f
swapf w_temp,w ; restore pre-isr W register contents
retfie ; return from interrupt
END

 

Hi,
You have initially set the delay value to be '9'. In the ISR, you have:
When the content of 'delay' is decreased until 0, bit 0 of Done is set, at the same time, the delay time should be restored. Otherwise, the next round the program entering the ISR, it will decrement the delay from 0, but not from 9.
Besides, I suggest you to use rotate to switch the LED since you're turning on only one LED each time.
Good luck

__________________
Superman returns..

 

Dumb mistake, again. It seems to work now. I will see if the A/D works for getting the value. Since the value will be changing I will just make two variables, Delay and DelayTemp, with the latter being the only decremented one.

Rotate is an great idea that I did not think about, but I may change the pattern in the future. I have to leave it as is if I decide on another pattern. There are other ways that I can reduce the code as well, but I do not need to, as the PIC has only the job of turning LED's on and off.

Thanks for your help.

Sean

 

A couple of comments on the ADC configuration:

But I think that you want to left-justify the result and read the eight most significant bits in the ADRESH resgiter (that is in bank 0).


Hope you'll have it working.

 

I corrected the a/d mistake of not enabling AN3. But my reasoning of using the lower result with a right justify was that I would get bits 0-7. I only need the value to go up to a max of 256, so 8 bits is enough. Do you recommend left justify and upper address because the value will not be zero in several pot positions?

 

Yes, you only need 8 bit-resolution, but you want to get the eight most significant bits of the result.

If you right-justify the result and read the least significant bits, what happens if the value is...
ADRESH = xxxxxx00 ADRESL = 00110011
or
ADRESH = xxxxxx01 ADRESL = 00110011

You wouldn't get unique results.


Left-justify the result and read the ADRESH register. You'll be still using 8 bits.

 

I tried the left justify and using the high bits, still didn't work. The problem was I was trying to write to ADCON0 and was still in Bank 1. Now it works!

Thanks everyone. I just hope I can learn quick enough to return the favor sometime.

Sean