With the default kernel 2.4 you get usleep() of 10ms, so
usleep(1)=usleep(1000)=usleep(10000)... thats 10ms. Then your program
does something and that's 10 more ms, so you get
20ms/read*1000read=20s.
I understand read_channel() as defined on ep93xx_adc.h is using EoC.
Have you tried looking at the input with an oscilloscope?
On Sat, Feb 21, 2009 at 10:59 PM, Girisha De Silva
<> wrote:
> Hey
>
> Thanks Rod for your reply. Anyways this is what I do in the loop.
>
> cur_ch = ADC_CH2;
>
> //discard two samples
> read_channel(adc_page, cur_ch);
> read_channel(adc_page, cur_ch);
>
>
> //read 1000 more samples
> for(j = 0; j < NOSAMPLE; j++)
> {
> usleep(1000);
> adc_result[j] = read_channel(adc_page, cur_ch);
>
> avg = adc_result[j];
>
> if(avg < 0x7000)
> avg = avg + 0x10000;
>
> avg = avg - 0x9E58;
> val = ((double)avg * 3.3) / 0xC350;
>
> sprintf(pBuff,"%f",val);
> fprintf(file,"%s\n",pBuff);
>
> }
>
> Hope I am doing it the correct way.
>
> Regards Girisha
>
> ________________________________
> From: Rod Nussbaumer <>
> To:
> Sent: Sunday, February 22, 2009 1:11:06 AM
> Subject: [ts-7000] Re:U Sleep
>
> How are you reading the ADC? Most ADCs have a bit somewhere to signal
> End-of-Conversion. If your loop is simply reading a register that is
> supposed to contain converted data, but is not waiting for EoC, that
> would explain erratic readings. If a time-delay is inserted, as with
> usleep(), it would allow time for the conversion to complete, and
> provide you with valid readings. Again, this is consistent with the
> behavior you are seeing. Can you confirm that you are reading the ADC in
> a way that assures it has completed a conversion?
> --- rod.
>
>
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