two GPIOTE / PPI tasks on a single pin

[Scott]

Hi,

We are trying to use GPIOTE / PPI to turn a MOSFET on A microseconds after an event clears a timer and to turn it off B microseconds afterwards.

It is easy to do this with a single GPIOTE toggle event, however that is not reliable and often changes to turning it off after A microseconds and on after B microseconds.

We should like to setup two GPIOTE tasks specifically to turn it on then off. Per the nRF52832 documentation that seems to be supported by the hardware, but there doesn't seem to be a way to do it using the SDK and we haven't been able to kludge it. We can use interrupts, but we want it to operate autonomously without CPU involvement.

Is there some way we can do that ? (and, if so, could official support be added to a future version of the SDK?)

Thanks,

~ Scott

[Håkon Alseth]

Hi Scott,

 

You can use the GPIOTE->TASKS_CLR and GPIOTE->TASKS_SET connected through PPI using two separate timer events, similar to what is setup here:

https://github.com/NordicPlayground/nrf52-timer-gpiote-ppi-hands-on/blob/master/main.c#L75

 

Note that if you want several things to occur within the same event, you can use the PPI.FORK functionality to trigger two tasks from the same event.

 

Best regards,

Håkon