what is GPI speed setting (SPI)in stmcube

[AOmar]

I have a question regarding to the selection of the GPIO speed setting in SPI configuration. as far as I understand is that it helps to adjuste the rising time of the signal.

my question is basically , how it is this being done in the controller ?

furthermore, what is the impedance measurment on each speed setting

Thanks

[Tesla DeLorean]

Yes, it is more of a slew rate setting

It is typically achieved by cascading transistor/inverter structures of increasing size, able to switch more current into a capacitive load.

If you have short traces, small loading, you can back-off the speed setting so as to avoid over/under-shoot and ringing.