HSE oscillator does not work on Nucleo-U385RG-Q board

[Spiker]

I try to get the HSE working on a Nucleo-U385RG-Q board by the standard settings in the STM32CubeIDE, but can't get it to work. I changed the default soldering connections per the UM3062 User manual to SB19 and SB21 Off, SB20 Off, SB3 and SB4 On. I monitored the HSE by redirecting it to the MCO pin (PA8 / D7). but got no signal. I monitored other clock signals, like the external LSE and the internal high speed oscillator via the MCO pin and had no problem to get a signal out.

Though the Cube's settings should start up the HSE, it didn't, and even when I added a line of code (RCC->CR |= RCC_CR_HSEON;) to enable the HSE oscillator, I did not get anything.

I have no problem to get this working on a Nucleo-C092RC board, so I wonder whether there is something wrong with the HSE oscillator on the Nucleo-U385RG-Q or with the soldering settings recommended in the manual.

I would appreciate any feedback, because I purchased more than 100 of these boards to use in an experiment, and I do need the precision of the HSE oscillator.

[AScha.3]

Hi,

> to enable the HSE oscillator, I did not get anything.

Nothing wrong with you or the board. :)

Just - there is no HSE crystal !

from -> https://www.st.com/en/evaluation-tools/nucleo-u385rg-q.html#cad-resources

see circuit:

Clock coming from st-link, so set hse bypass and it should work. (with default solder bridges )

And maybe do update the st-link, there you can decide which clock is coming to the U385 , 16M probably.

So it only can work with powered and running st-link cpu; if you want U385 having its own clock,

you have to solder the missing parts, 16MHz crystal and caps, and adjust the solder bridges to have the crystal connected and st-link disconnected.

[Gyessine]

Hello @Spiker and welcome to STcommunity
as you can see in the board scheamtics the HSE clock is not implemented for cost reduction purposes

you didn't find any problems with the Nucleo-C092RC because the board supports a HSE buy default

you can use the Bypass mode to use the HSE clock of the STlink but check the frequency
I hope that this information helps you solve your problem.

Gyessine