RE: nRF52 SAADC Sampling Rate w/ ESB

Stefan Birnir Sverrisson — Wed, 10 Aug 2016 11:23:28 GMT

I think it is matter of trial and error to find out if the nRF52 can handle this high ESB transmit rate and this high sample rate. I think this is a matter of how much the nRF52 M4 CPU can process. The SAADC itself does not however put any strain on the CPU, as it can sample autonomously and transfer samples directly to RAM via EasyDMA, but at some point you would need the CPU to process the samples in RAM, transfer them via SPI, UART, BLE or something else, and that requires CPU time. I suspect anyway that if transmitting 800kbps with ESB works and you receive your data from serial interface, UART, SPI etc, then processing data from SAADC will not be more CPU demanding than processing data from any serial interface. The SAADC can handle up to 200k samples per second so it will not be a bottleneck.

For your oversampling and calibration questions, I think the saadc_low_power example on Github has some documentation on this. Also, there are a lot of in-code documentation that could help understand the rules of oversampling, scan mode and calibration.