The strange GPIO pullup output voltage

[Rian]

I tried 3 boards F407vet6 x2 and F427 x1.

I found both pullup and pulldown gpio output in PP and OD will put a low voltage. 20mV in down and 50 mv in up.

This situation is based on the stdperiph-Lib

However, use the Hal-Lib to implement the gpio output, it will work well.

I've tried to search for simillar issues on internet, but none.

[waclawek.jan]

Read out and check/post the GPIO registers content during your test.

JW

[TDK]

The SPL can't change the low-level hardware behavior. It's accessing the same registers as HAL and the registers dictate the behavior of the chip.

Likely to be some other explanation.