Re: ADSC bit in ADCSR

Here is a snippet of code that performs A/D conversion on the ATmega103,
which is very similar to the m128. Per Atmel's recommendation, the
processor is in SLEEP mode to reduce noise while the conversion is in
process.

{ ---------------------------------------------------------------------
Analog inputs

@ADC Samples the ADC for a given channel
--------------------------------------------------------------------- }

$DE EQU ADC-GO \ Start an ADC sample at 50-200 KHz

CODE @ADC ( chan -- val)
   TL ADMUX OUT
   $A0 R16 LDI R16 MCUCR OUT \ Enable sleep mode
   ADC-GO R16 LDI R16 ADCSR OUT \ Start the sampling
   SLEEP
   BEGIN ADIE ADCSR SBIC AGAIN \ Await end of sample
   ADCL TL IN ADCH TH IN \ Read the sample
   R0 CLR R0 ADCSR OUT \ Disable the ADC
   RET END-CODE

LABEL <ADC>
   ADIE ADCSR CBI RETI END-CODE

<ADC> ADCCaddr INTERRUPT

> -----Original Message-----
> From: swiftx-bounce_at_forth.com [mailto:swiftx-bounce_at_forth.com]On Behalf
> Of Viviane.Beullens
> Sent: Tuesday, September 02, 2003 9:46 AM
> To: swiftx_at_forth.com
> Subject: [swiftx] ADSC bit in ADCSR
>
>
>
> Hi,
>
> I am working with the ATmega128 and am trying to do
> A/D conversion. It seems to be enough simple and
> the code below should do it.
> THe problem I have is I can't set bit 6 of the
> ADCSR (ADSC bit).
> Did some of you encountered the same problem?
>
>
> Thanks in advance for any useful info you can provide.
>
> Viviane Beullens
>
> \ Code
>
>
> TARGET
>
> |U| |S| |R| BACKGROUND SCRIBE
>
> VARIABLE RESULT
>
> \ Select in ADMUX inputpin 0 in PORTF
> : selectMUX0
> ADMUX c@ 1 OR ADMUX C! ;
>
> \ Request a conversion setting ADSC bit in ADCSR, bit 6
> : SetADSC ADCSR C@ 64 OR ADCSR C! ;
>
> \ Set enable bit in ADCSR, ADEN, bit 7
> : SetADEN
> ADCSR C@ 128 OR ADCSR C! ;
>
> \ Disable ADEN
> : DISABLEADEN
> ADCSR C@ 127 AND ADCSR C! ;
>
> \ Read result when ADIF is high
> : READRES ( f -- )
>
> ADCL C@ RESULT 1+ C! ADCH C@ RESULT C! ;
>
>
> \ Do conversion until ADIF bit is set
> : DoA/D
> BEGIN
> selectMUX0 SetADSC SetADEN
> ADCSR C@ 16 AND
> UNTIL
> READRES
> DISABLEADEN RESULT @ . ;
>
> : SCRIBEACT SCRIBE ACTIVATE BEGIN PAUSE DOA/D AGAIN ;
>
>
>
> : /SCRIBE 0 RESULT ! SCRIBE BUILD ;
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Received on Tue Sep 02 2003 - 10:03:55 PDT