Simple SAADC sample convert always fail on ASSERT

[Fabien Duay]

Hi,

With the latest SDK (17.0.2) I try to use the SAADC module in blocking mode but when I call <nrf_drv_saadc_sample_convert> an ASSERT is always triggered in <nrfx_saadc.c> source file.

This ASSERT is triggered atfer 10000 tries and wait for the <NRF_SAADC_EVENT_END> event, which never occurs.

You'll find attached a little project to reproduce this ASSERT error. I'm using a custom board but you can use the DK board as well. The error is shown on RTT immediately as startup (the <saadc_read> function is called directly in the <main> function).

Any helpful hint for me?

Fabien

[Jørgen Holmefjord]

Hi,

The problem is that you have configured the SAADC with OVERSAMPLE set to 8X, which requires you to trigger the sample task 8 times before the END event is generated. You can fix this by enabling BURST mode for the channel, by adding this line to your saadc_init function:

channel_config.burst = true;

Burst will make the SAADC sample the channel X_OVERSAMPLE times from a single SAMPLE task.

Best regards,
Jørgen

[Fabien Duay]

Hi Jorgen,

Thx for the tips. It was the trick I was waiting for.

I'm pretty sure I've already read about that on the DevZone (I think I need some vacation)..

Anyway, thx for the quick and great support.

Best regards,

Fabien