> On Jan 27, 2017, at 4:43 PM, Renzo Fabián <[email protected]> wrote:
>
> john3909,
>
> there's no reason to use the PRUs. I only need read 6 analog inputs in
> real-time. I thought the only way would be using the PRUs. And the best way
> by means of lbpruio.
Well, it all depends on what you mean by realtime? The ADC on the AM3358 uses a
sequencer that samples the analog channels at a fixed sampling rate and places
those samples in a FIFO. It does not matter if you use PRU or the IIO driver,
because the channel sampling occurs at the same time. The difference is the PRU
samples the ADC status and then copies the data into DDR and the IIO driver
uses DMA to move the samples into DDR. The IIO driver is faster and can achieve
higher sampling rates. Also the IIO driver is easier to use because you just
read from /dev/iio:deviceX. Better still, you have both PRUs available for more
important work.
Regards,
John
>
> El viernes, 27 de enero de 2017, 2:10:27 (UTC-2), Renzo Fabián escribió:
>
> I have the following C code's parts that uses tables of sins and cosins to
> calculate a fundamental phasor of 60 Hz electrical system using 16 samples
> per cycle (960 Sps):
>
> float cosins[]={1, 0.92388, 0.70711, 0.38268, 0, -0.38268, -0.70711,
> -0.92388, -1,
> -0.92388, -0.70711, -0.38268, 0, 0.38268, 0.70711, 0.92388};
>
> float sins[]={0, 0.38268, 0.70711, 0.92388, 1, 0.92388, 0.70711, 0.38268, 0,
> -0.38268, -0.70711, -0.92388, -1, -0.92388, -0.70711,
> -0.38268};
>
> ...
>
> for(i=0; i <16; i++){
> ret_r=x[15-i]*cosins[i]+ret_r;
> ret_i=x[15-i]*sins[i]+ret_i;
> }
>
> return 0.088388*ret_r -0.088388*ret_i*I;
>
> Is it possible to perform this using the libpruio in order to read 6 analog
> inputs? If yes? What is the best way to implement it if other operations were
> need, i.e. compute the division of 2 phasors.
>
> Thanks.
>
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