How to find matching drive level for LSE crystal?

[Lars Beiderbecke]

After reading the Oscillator Design Guide, I picked a LSE crystal for my F7 from the list provided in that guide.

But how do I know what the appropriate drive level is? My crystal has a max drive level of 1 uW. But does that corresponds to Low, MediumLow, MediumHigh, or High as described in the Reference?

In none of the documents provided by ST I have found numerical descriptions of the drive levels provided by a F7. There is a drive level list for the HSE, but I'm not sure if I can use that for the LSE as well.

[Lars Beiderbecke]

I stand corrected, in the Oscillator Guide is a table (on page 22) that shows g_m (min)/G_m_crit_max in terms of drive level. Since my crystal has g_m_crit = 0.7980, that means that G_m_crit_max must be 1.7 and thus drive level is MediumHigh.

[Lars Beiderbecke]

How do I set the drive level in CubeMX? Do I have to write the register directly instead?

[Vangelis Fortounas · Accepted solution]

hello

use this macro to set the drive strength

__HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_MEDIUMHIGH)

it is inside RCC header