nrf52832 uart baudrate issue

[zhangys]

Hi all,

  We met a problem with uart while producting our device. It happened when we communicating with our NB module(BC28), then i catch the waveform by the oscilloscope, the baudrate of whom always return "ERROR" is 9433.96bps, the correct one is 9615bps, and this issue happens 10pcs in 100pcs boards.

efforts:

  1. We tried to exchange the nrf52832 chip, it not work.

  2. Change a new chip, it worked.

Q:

  1.Is it need to config the hfclk to use uart? havent found similar code on the uart example.

Wishes:

  1.We are about to product more devices, it's urgen to solve this issue.

Thank you!

[Simonr]

Hi

Are you ramping up your HF clock before running the UART? If not, inaccuracies like this might occur. I would strongly suggest enabling the HF clock when using UART. 

Also, I'm not sure I understand what you've tried. Did you just desolder the nRF52832 and solder on a new one on the same PCB which did not help the UART accuracy? But testing on an entirely new board with all new components worked as intended?

A common issue is that the crystal(s) have been soldered on 90 degrees the wrong way on some boards, causing issues like this. Can you please check for that on your dysfunctional boards?

Best regards,

Simon