nrf_delay uses NOP() but it's called in app_timer2.c and drv_rtc.c

[nothingmuchyou]

Hi, 

I've read in these forums and seen the machine instructions within the C code that nrf_delay_us (which BTW is used to do nrf_delay_ms) is implemented by executing a series of nop instructions. This is a problem for handling interrupts from other modules promptly, and frankly I'm not really sure why it's so integrated in the library. 

In our project we are using app_timer version 2 which uses drv_rtc.c and nrf_delay module for Bluetooth. We are also using a separate timer and seeing that interrupt get effected by this. While the interrupt is supposed to trigger every 1 us, it actually only triggers every 11 us, I think because of this NOP() delay. 

My question is: What's the best way to get rid of the nop nrf_delay_us implementation? Do I overrride it? 

Thanks for the help

[Einar Thorsrud]

Hi,

I understand that this is a problem in your specific use case. But using a TIMER (which is the only other alternative) in the app_timer library is not an option and will not be a good design choice for this module.

If this is a blocker for you, then you would have to either modify the app timer (to use the TIMER to wait instead of busy waiting), or avoid using the app_timer altogether. Without knowing the details of your design I suspect the latter would make more sense.

[nothingmuchyou]

I guess I'm still surprised that this implementation is allowed but thanks for your response.