SAADC callback

[RichieJH]

I have this working and producing good and accurate results, but I'm still puzzled by some of the examples in the SDK and the documentation.

I am using the processor to call for the saadc sample (i.e, not ppi) and I set the nrf_drv_saadc_buffer_converts immediately before hand:

err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0], SAMPLES_IN_BUFFER);
err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1], SAMPLES_IN_BUFFER);
err_code = nrf_drv_saadc_sample();

In the examples in the SDK (12) and elsewhere I also see another nrf_drv_saadc_buffer_convert call in the callback handler prior to reading the data in the buffer:

err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAMPLES_IN_BUFFER);

My question is what is the point of calling this again in the call back and why is the first argument p_event->data.done.p_buffer? I've read the documentation but it still doesn't make sense to me. Could anyone explain this as if they are speaking to a 5 year old?

Many thanks,

[acha]

Hello all, I have question about buffer filling, if there is multiple channels initialized for conversion, that's means that p_event->data.done.p_buffer[0] contains the converted value for first channel enabled, p_event->data.done.p_buffer[1] for the second one, and p_event->data.done.p_buffer[2] for the third one?

[Jørgen Holmefjord]

Yes, this is correct.

[Jørgen Holmefjord]

If you have not connected channel B it will be floating, giving you unstable reading. What are you trying to achieve with this? Are you getting wrong reading if you connect the channel before measurement?

[acha]

Yess, when B and C are floating and a tension in channel A, I have unstable reading in the channel B when I set a tension in the channel A, when I set a tension in channel B, I have unstable reading in channel C, when I set tension in the channel C, I dont have instable reading o_O.