nRF52840 GPIO timing question

[GlennF]

We intend to connect an A-D converter to GPIO lines in SPI mode. The ADC generates a done pulse that is positive 3.3V and 56ns to 64ns wide.

Looking at v1.1 datasheet ... GPIO 6.10.5 discusses output Rise/fall times, but nothing about inputs. 

And the GPIOTE section,  6.10.5 Electrical specification  is blank.

So the question is, can a GPIOTE reliably respond to a pulse this narrow?

[GlennF]

Forgot to mention, using Low Power mode, MClk/16, 16.385 MHz crystal

[Jared]

Hi,

I don't think that this has been measured and specified. My guess is that it should take less than 100 ns but i'm uncertain if it's less than 56 ns. Exactly what ADC are you planing to use? I think the quickest way to find out is to try and see if it can respond to it. 

regards

Jared

[GlennF]

So, we wrote a quick test app and I verified that it reliably responds to a 20 ns wide pulse. My generator doesn't create pulses more narrow that this, so I couldn't find its pain threshold, but this reassures me that it should do fine with a 56 ns pulse width.