nRF54 UART connection failure at low temperature

RE: nRF54 UART connection failure at low temperature

Brutus — Thu, 09 Apr 2026 12:38:04 GMT

Hi,

Thanks for the tip! will look at the sample code and try to tweak it to my needs

RE: nRF54 UART connection failure at low temperature

Brutus — Thu, 09 Apr 2026 12:36:33 GMT

Hi Jonathan,

for the HF crystal, we are using ABM11W-32.0000MHZ-8-D1X-T3 from Abracon devzone.nordicsemi.com/.../5556.ABM11W.pdf

For our test setup, we connected 2 probes, 1 on the TX and 1 on the RX, to the oscillator, and saw that the TX line leaving the nRF went flat once the -18°C threshold was reached.

Only our board with the nRF is in the climate chamber and the UART lines are brought outside of the chambre, so the UART to USB is always at room temp.

I'll try to disable the external crystal and use only the internal one

RE: nRF54 UART connection failure at low temperature

Turbo J — Thu, 09 Apr 2026 11:42:38 GMT

Try to keep the HFXO on. Don't remember right now where the sample code for nrf_cock_control was.

HFINT tolerance is slightly too high for stable UART operation.

RE: nRF54 UART connection failure at low temperature

JONATHAN LL — Thu, 09 Apr 2026 11:30:35 GMT

Hi,

Are you using the external crystal as source, have you tested with internal HFINT and does the issue persist if so?

What crystal, can you share the datasheet.

Have you probed the TX pin during the connection loss? or done any other debugging steps?

What does the test setup look like? is the UART service interface also in the temp chamber?

Regards,
Jonathan