Problems with QD2 ADC

[Zetta08]

I am using the QD2 and I have problems with the ADC

The instructions for Init_ADC init code are:

                     LDA     #$18
                     STA     SPMSC1

                     LDA     #$F0
                     STA     ADCCFG                                               
      

                     MOV     #$01,ADCSC1
      

                     LDA     #$02
                     STA     APCTL1

In de Loop:

                    BSET    ADCSC1_ADCH1,ADCSC1
              
            

WAIT           TST     ADCSC1 

                    BPL     WAIT
                                                                               
                    LDA     ADCRL   

                    ........................

But ADCRL it is always $00

I need some help  
That I am making bad

[bigmac]

Hello, and welcome to the forum.

I will comment your code, and you can judge whether it meets your intention - I don't believe it does.

---

Zetta08 wrote:

I am using the QD2 and I have problems with the ADC

The instructions for Init_ADC init code are:

     LDA  #$18
     STA  SPMSC1

     LDA  #$F0
     STA  ADCCFG                                               
      

     MOV  #$01,ADCSC1  ; Commence conversion Ch 1
      

     LDA  #$02         ; Select Ch 1 for analog operation
     STA  APCTL1

In de Loop:

     BSET ADCSC1_ADCH1,ADCSC1
     ; Abort conversion & commence new conversion Ch 3

WAIT:
     TST  ADCSC1 

     BPL  WAIT         ; Loop until conversion complete
                                                                               
     LDA     ADCRL   

     ........................

But ADCRL it is always $00

---

Regards,
Mac

[Zetta08]

Hello Mac

For that say that  
BSET    ADCSC1_ADCH1,ADCSC1  ;it begins a new conversion in the channel CH3

In the Loop I use the following instructions but it always jumps to HAB_DISPARO

This means that ADCRL is always > #$64 (Not #$00, sorry)

LDA                 ADCRL                      

                      CMP     #$64
                      BHS     HAB_DISPARO             
             
INH_DISPARO    BSET    F_NIVEL,CONDICION
                      BRA     FIN_CICLO

HAB_DISPARO   BCLR    F_NIVEL,CONDICION  

..............................

Thank you and regards

Zetta08 

[bigmac]

Hello Zetta08,

I might have expected that your intent was to measure channel 1, rather than channel 3.  As you have not selected analog operation for channel 3 (APCTL1 register), it is possible that this input may have its digital pullup enabled, which may account for your observations.

I suggest that you don't use the BSET instruction for initiating a conversion - simultaneously write to all bits of the ADCSC1 register to reduce the confusion over what bits are already set.

   MOV  #$01,ADCSC1  ; Commence conversion Ch 1

or 

   MOV  #$03,ADCSC1  ; Commence conversion Ch 3

Regards,

Mac

[Zetta08]

Finally I found the solution.

It is necessary to disable the PTA1 before beginning the conversion.

In my case the correct instructions are:

Common initialization of the write once registers

        LDA     #$F0
        STA     ADCCFG

; ADCCFG: ADLPC=1,ADIV1=1,ADIV0=1,ADLSMP=1,MODE1=0,MODE0=0,ADICLK1=0,ADICLK0=0

In de loop:

              LDA     #$02                             ; Disable the Port PTA1 as I/O
              STA     APCTL1
              MOV     #$01,ADCSC1                ; It begins the convertion

                                                           ; Or:   BSET    ADCSC1_ADCH1,ADCSC1
          

WAIT       TST     ADCSC1                        ; Waits to that finishes the conversion                
              BPL     WAIT
                                                                  
              LDA     ADCRL

              . . . . . . . . . . .    

It works correctly

Thanks to all and greetings