S08QG8 ADC Problem - Watchdog Timeout while waiting for conversion

Mellitus1967 — Sun, 12 Apr 2009 10:29:45 GMT

Hey all;

I took a class a couple years ago using the MC68HC908QY4 with Assembler. Thats the limit of my experience programming microprocessors. Trying to sample two conditioned signals from an aerometer and import them into Matlab (i.e datalogger) but running into trouble getting the basic ADC working

Using S08QG8 (Spyder discovery kit) and CodeWarrior 5.7.0

With both the simulator and the chip monitor (SofTecHCS08) the program gets locked in an endless loop executing ADC_WAIT and triggers the Watchdog

In the simulator the ADACT bit sets and clears and the result is stored into ADCRL but COCO never sets

In the chip monitor the ADACT bit sets and clears and the result is stored into ADCRL then COCO sets but the program never branches

Am I missing something really simple?

Any help would be appreciated

complete code included as attachment

;***********************************************************************
; Code Section: ORGed to start of flash                                *
;               this is where you put all of the program code          *
;***********************************************************************
              org    FLASHSTART
;Standard startup code
MAIN:   lda #$D2            ;BKGDPE Enabled
            sta SOPT1     ;systems options
              lda #$00
            sta   SOPT2        ;systems options
             ldhx #RAMEND+1       ;re-initialize the stack pointer
             txs
             cli              ;enable interrupts

;Replace this with program startup code
MAININIT:   bsr   INIT_GPIO         ;setup GPIO ports
              bsr   INIT_ADC   ;initialize ADC for pins ADP0 and ADP1

;Replace this with your main execution loop
MAINLOOP:    bsr GET_ADC        ;the ADC voltage is in A
            bsr ADC_OUT        ;the ADC voltage is in Port B

ENDPROG:             ;if you don't feed the watchdog, the CPU will reset
            sta   WATCHDOG      ;feed the watchdog
            bra   MAINLOOP

;-----------------------INIT_GPIO Subroutine----------------------------
INIT_GPIO:   lda   #$00            ;zero byte
              sta   PTBD            ;clear port B data
              sta   PTBSE           ;turn off slew rate for all port B
              sta   PTBDS           ;set drive strength to low for all port B
              sta   PTBPE           ;disable internal pull up resistors for all port B
              lda   #$FF            ;one byte
              sta   PTBDD           ;enable output for all port B
            rts

;-----------------------INIT_ADC Subroutine----------------------------
INIT_ADC:   bsr ADC_STOP        ;disable ADC while configuring
            mov #$00,ADCCFG    ;fast clock settings,8b mode
            mov #$00,ADCSC2    ;software trigger, no compare
            bset ADCPIN1,APCTL1 ;enable ADC pin ADP0
            rts

;-----------------------GET_ADC Subroutine-----------------------------
;perform a single conversion on the ADC
;channel number (0-7) passed in accumulator A
;ADC data returned in accumulator A
GET_ADC     mov   #ADCPIN1,ADCSC1        ;stop current pin and initiate conversion
WAIT_ADC    brclr COCO,ADCSC1,WAIT_ADC    ;poll COCO until conversion complete
            lda ADCRL                  ;read data, clearing COCO
            bsr ADC_STOP  ;the ADC voltage is in A
DONE_ADC:   rts

;----------------------ADC_OUT Subroutine------------------------------
ADC_OUT:    sta PTBD            ;send sample to output port
           rts

;-----------------------ADC_STOP subroutine----------------------------
;power off the ADC by writing CH=11111 to ADCSC1
ADC_STOP mov #STOPADC,ADCSC1
rts
;----------------------end code-----------------------------

James

Re: S08QG8 ADC Problem - Watchdog Timeout while waiting for conversion

Summerville — Sun, 12 Apr 2009 19:40:01 GMT

James,

I tried you code and it worked perfectly for me on a QG8. The chip that comes with the spyder (the 8 pin one) is a QG4. Are you using the 16pin QG8 or the 8pin QG4? Your program is configured to run on the QG8 as written- a couple of EQU's must be changed to run on the QG4. With the in-circuit debugger, this runs for me on the QG4 but the ADC does not work properly.

Re: S08QG8 ADC Problem - Watchdog Timeout while waiting for conversion

bigmac — Mon, 13 Apr 2009 03:14:08 GMT

Hello,

Running the code on a QG4, using equates for the QG8, may work but is not guaranteed to do so. Primarily, the stack is placed at an invalid RAM location, and the code is placed at an invalid flash location for the QG4.

RAM and flash memory may exist at the specified locations, but is not tested, and not guaranteed.

Regards,

Mac

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S08QG8 ADC Problem - Watchdog Timeout while waiting for conversion

Re: S08QG8 ADC Problem - Watchdog Timeout while waiting for conversion

Re: S08QG8 ADC Problem - Watchdog Timeout while waiting for conversion