Internal Pull up STM32G4 series

STUser34 · ‎2025-02-03

Hello,

I am using the internal pull up for the input pins, but when read the port status using the program, it always reads 0 instead of 1. I expected it to read 1 and if make that pin grounded it shall read 0.

Hl_st · ‎2025-02-04

Yes I think the problem should be solved if you remove that 4K resistor

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gbm · ‎2025-02-04

I can see 5 problems with the "existing" version and 3 with the new one. In the schematic they are labeled as R and C. Remove all of them and you circuit will work.

My STM32 stuff on github - compact USB device stack and more: https://github.com/gbm-ii/gbmUSBdevice

Ozone · ‎2025-02-04

I would say, check the datasheet of your MCU for the value range of the internal pull-ups, and check it through.

I see nothing wrong with reading a 0-value for an unactuated switch. You could just drop the pull-up configuration, as it is most probably pointless in this situation.

I think the aim of the whole exercise is to differ between actuated switch state (1) and unactuated switch state (0).
And that does most probably work.