Wireless timer synchronization

[D_Crow]

Hi,

I am working on a project that involves synchronised sensor sampling between the central and peipheral devices. I have followed the example given byAudun here. Using his example on github I am able to get GPIO pins toggling with less than 1us jitter on an nRF52840DK central (time master) and nRF52832DK peripheral. I have custom PCBs incorporating the nRF52832 and analog front end with an external ADC. When I try the same code on this PCB I observe up to 25 us of jitter between the pins on the nRF52840 central and custom PCB peripheral.

I have been trying to adjust the TX_CHAIN_DELAY value to correct the jitter but cannot get it to match the performance I see when using two dev kits. I have a 10ppm 32MHz crystal on the custom PCB.

Welcome to any suggestions if anyone else has tried this method on custom hardware.

Thanks,

Daragh

[tesc]

Hi,

Are you running the same code on the custom board as you run on the DK? I.e. no added features etc., especially if there is radio usage, code running at higher priority, etc.

Can you confirm that what you see is 25 us jitter, and not e.g. 23 us delay with a 2 us jitter on top?

Is there any pattern to the jitter?

When toggling pins, are you still toggling normal pins on the custom hardware, or do the toggling go through the analog front end / external ADC?

Are other radio protocols working well on the board, such as e.g. BLE?

Regards,
Terje