low power with STM32U5 and LPUART

[nicolas]

I'm trying to port code from STM32L4 to STM32U5.

The STM32L4 code was using the LPUART, with a baudrate of 20k, clocked with HSI but in stop2 mode the HSI was stopped, it was able to wakeup and read incoming data. This configuration was using ~10uA.

I'm trying to do the same with STM32U5 but i think the HSI is not stopped during stop2 so it use ~200uA. AFAIK the knowledge base example keep HSI running.

Is it possible to use the same configuration with the STM32U5 ? If yes, is there an example ?

Or the only solution is to use the LPBAM with STM32U5 (like in LPBAM_LPUART_TransmitReceive) ?

Thanks in advance.

[Uwe Bonnes]

RM945 chapter 6 10.7 tells for stop mode "The PLL, the MSI
(MSIS and MSIK) RC, the HSI16 RC and the HSE crystal oscillators are disabled. The
LSE or LSI is still running."
So look for other current suckers...