measuring input GPIO pin frequency with soft device running

[adriand]

Hello,

is it possible to measure frequency from 1Hz up to 400kHz (50% duty cycle) on gpio pin having soft device enabled with Peripheral functionality? The measurement will be invoked on demand by the connected central device. I will use nRF51822, rev. 3, S110 or S130, SDK 8 or 9.

If this is not possible, please tell me if following scenario would be ok:

• invoke measurement
• disable soft device (disconnection from central)
• manage measurement (what's the best way: which timer?, PPI? GPIOTE?)
• enable soft device

Thank you!

btw, what is the maximum frequency that can be measure on gpio pin?

[Susheel Nuguru]

ah I see. It is doable Configure Timer1 in timer mode to generate an event in X seconds. This event should be converted to TASK_STOP using a PPI Configure other peripherals as below but do not enable the last block timer 2 yet.

When you want to start the measurements, START the timer1 and timer2.

After X number of seconds, Timer2 counter will have counted the number of rising edges of the pin in X seconds. get the value into timer CC[n] by triggering a CAPTURE[n] task on timer 2.

Divide Timer2->CC[n] by X and you have your frequency. This should work even with softdevice as we are not using any interrupts.

[Susheel Nuguru]

at the end of the day you will get a very good understanding of all these peripherals :) Good luck and let me know how it goes.

[adriand]

@Aryan - thank you for the great explanation! I will try your method as soon as I get the sensor. Thx!

[Susheel Nuguru]

your welcome, please let me know if it worked after you implement it. I can help you if there are any problems you face. I have changed the title for this thread to reflect the contents, i hope it is ok.