Maximum sampling rate on nRF51822 digital I/O?

[sd]

My application involves driving a digital-output (PDM) MEMS microphone at 1 -- 3.25 MHz with a clock generated on a GPIO.

devzone.nordicsemi.com/.../

The output of the microphone is a digital signal with data at the rate of the supplied clock. I'd like to sample this I/O at the highest rate possible; is this a scenario I can achieve with the nRF51822? (Assume a 16 MHz input clock to the nRF51822.)

[JohnBrown]

I'd say you might need to drop down into assembly language for this - I assume you're not trying to do this while a soft device is running? If so, then I think you're doomed.

[JohnBrown]

Even if you're not transmitting, the SD will inevitably be using some CPU time, which is likely to interfere with what, essentially, is a synchronous clocked data stream. On the other hand, I don't know quite what it is you are trying to do. It could be that, if you are only interested in detecting a loud noise, for example, you might be able to subvert the SPI block into reading the 8 MSBs of the value.