Safe temperature range for nRF52840 - nRF9160 UART 115200 without external crystals for HF clocks

[Michal Mühlpachr]

Hi,

what is safe temperature range for nRF52840 - nRF9160 UART communication on 115200 baudrate without external crystals for HF clocks please ?

Thank you.

[Simonr]

Hi

As stated in the UART peripheral chapter of the product specification of both the nRF52840 and nRF9160: The external crystal oscillator must be enabled to obtain sufficient clock accuracy for stable communictation. So no, the UART clocked from the internal RC oscillator will not be sufficient to ensure stable UART communication at any temperature. The RC oscillator also uses the external HF clock to calibrate and is prone to temperature changes, so this would be a bad idea.

Best regards,

Simon

[Michal Mühlpachr]

Thank you. Why then in Serial LTE modem is CONFIG_SLM_EXTERNAL_XTAL=n as default ?