What is 'digbypass clock source'?

[diverger]

Hi,

I started a design with STM32U5 series MCU. In the STM32CubeX's HSE settings, there is a new option "DIGBYPASS Clock Source'. What's the differences with the old 'bypass clock source'?

Thanks.

[Uwe Bonnes]

Probably DIGBYPASS is an obfuscation of RCC_CR_HSEEXT:

Bit 20
HSEEXT: HSE external clock bypass mode

This bit is set and reset by software to select the external clock mode in bypass mode.
External clock mode must be configured with HSEON bit to be used by the device. This bit
can be written only if the HSE oscillator is disabled. This bit is active only if the HSE bypass
mode is enabled.
0: external HSE clock analog mode
1: external HSE clock digital mode (through I/O Schmitt trigger)
Bit 19

[Bouraoui Chemli · Accepted solution]

The digital bypass mode is the same as the old bypass mode. The external user clock must comply with the specifications provided in Table 77 high-speed external user clock characteristics. (see STM32U575 datasheet).