Maximum sampling rate on nRF51822 digital I/O?

RE: Maximum sampling rate on nRF51822 digital I/O?

Charles Manning — Tue, 24 Feb 2015 01:52:07 GMT

The soft device needs the CPU for its own function. There are times when the soft device can hog the processor for, if I recall correctly, over 1 millisecond. During this time you have no CPU - not even interrupts.

RE: Maximum sampling rate on nRF51822 digital I/O?

Stefan Birnir Sverrisson — Mon, 23 Feb 2015 15:16:19 GMT

I am not very sure on what you intend to do but if you want to sample analog input signal then the internal nRF51 ADC has the potential to do that. However, the highest sampling frequency of the ADC is 50kHz with the lowest 8-bit resolution. When you use the softdevice, the sampling frequency is further limited, as JohnBrown has already pointed out. You could read more about the sampling limitations here.

RE: Maximum sampling rate on nRF51822 digital I/O?

JohnBrown — Fri, 20 Feb 2015 08:04:54 GMT

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.

RE: Maximum sampling rate on nRF51822 digital I/O?

sd — Thu, 19 Feb 2015 22:28:11 GMT

Yes, the SoftDevice will be part of the application. By 'running' do you mean transmitting? If so, then no, I know that that isn't possible. Otherwise, can you elaborate why it's a 'doom' scenario? (I'm willing to sacrifice quality to make it work.)

RE: Maximum sampling rate on nRF51822 digital I/O?

JohnBrown — Thu, 19 Feb 2015 17:43:13 GMT

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.