ESP32 Forum

Hi,

I use ESP32-S3-mini Modul.

I try to send on UART U0TXD/GPIO43.

The U0TXD/GPIO43 is NOT connected with the RX PIN from other uC and the pull-up Resistor is removed.

I see on my scope a low pegel ~ 1,0V.

If I connect U0TXD/GPIO43 with RX PIN from my uC -> the pegel is still ~1,0V.

The low pegel low pegel is to high, the serial UART will not work.

Please, do you have a hint? What can help?

'Pegel' is not an English word - you're likely looking for the word 'voltage'. Aside from that, that module has a 500 ohm resistor in series with the Tx pin, and from your voltages it looks like there's an 1K or something pullup externally to 3.3V. Are you sure you removed all pullups? Also, any chance that there's something conductive under the module (water?) that forms an impromptu pullup?