Is LSE essential in STM32WB55RGV6 BLE application?

Lep · ‎2022-06-10

I make a pcb board with stm32wb55rgv6, but my LSE doesn't work and this part of the circuit was accidentally destroyed in my soldering process. Can i just use HSE or LSI in replace of LSE in BLE application? And what's the limitations?

Remi QUINTIN · ‎2022-06-21

LSE is usually used to provide the clock to the RTC. The RTC in turn gives the time base tick for the timer server that is used for all BLE timings. But note that LSE is also the clock used during low power mode.

For example, during a BLE connection, when data have been exchanged and the device is waiting for the next connection interval, it enters in STOP2 mode. But this is only achievable with the LSE clock.

You can also use HSE/1024 for the RTC but in this case you won’t be able to achieve low power mode.

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Remi QUINTIN · ‎2022-06-21

LSE is usually used to provide the clock to the RTC. The RTC in turn gives the time base tick for the timer server that is used for all BLE timings. But note that LSE is also the clock used during low power mode.

For example, during a BLE connection, when data have been exchanged and the device is waiting for the next connection interval, it enters in STOP2 mode. But this is only achievable with the LSE clock.

You can also use HSE/1024 for the RTC but in this case you won’t be able to achieve low power mode.

Lep · ‎2022-06-21

Thank you=) .