Clock source confusion with lora_end_node example on stm32wl nucleo

[tj_scion]

 

Is it possible or advisable to use the tcxo as the clock source in a lora end node application? The default configuration in the Lora end node example code uses the MSI as the clock source but surely the tcxo would be a better and more stable option? There is some mention of the tcxo in the radio drivers but it's unclear if selecting the HSE as the clock source in cube mx is enough or whether the code requires further modifications to support it.

[Issamos]

Hello @tj_scion 

Using tcxo as a clock source instead of MSI is possible you just have to make sure that the frequencies are not going to change anywhere. Is it better or not, that depends on many conditions. The best way to answer this question is to test your application with both configurations and than make your decision which one is the best.

Hope this answers your questions. Please check this answers as best answer if you're satisfied.

Best regards.

II

[Tesla DeLorean]

The use of the TCXO would definitely be preferable (improved receive margins), especially if you can have it on at all times. Outside of the radio core, the STM32 running off a tight and stable clock probably isn't critical. Switching between clocks sources and modes would obviously significantly complicate your code implementation

@Alec BATH can the Semtech core use the TCXO OSC_IN independently of the STM32 core?

[Tesla DeLorean]

My expectation is that you code enable the TCXO, select HSE Bypass, and then pick an entirely different clock source and PLL configuration to run the code on the STM32 side of things.