UART unable to run on self power, only when enter keil debug mode.

RE: UART unable to run on self power, only when enter keil debug mode.

Didrik Rokhaug — Fri, 24 Nov 2023 17:16:11 GMT

Hi,

Which SDK and version are you using?

If you are using the nRF Connect SDK, I recommend you go through our nRF Connect SDK Fundamentals course at our Nordic Developer Academy: https://academy.nordicsemi.com/courses/nrf-connect-sdk-fundamentals/

Best regards,

Didrik

RE: UART unable to run on self power, only when enter keil debug mode.

zak_22621100 — Tue, 21 Nov 2023 01:32:56 GMT

Hi haakonsh

where to enable "pullup resistor on the RX pin" ?

Thank you

RE: UART unable to run on self power, only when enter keil debug mode.

haakonsh — Fri, 17 Nov 2023 13:01:32 GMT

Most likely your HFXO is not running. The UART peripheral needs a stable clock to operate, and the internal 64MHz RC oscillator becomes just stable enough when a debugger is attached.

Also, you need to enable the pullup resistor on the RX pin, if it's left floating the UART peripheral will encounter errors.