ESP32-S3 Low voltage causing UART pins to become defective?

[D0T-C0M]

I have a esp32-s3 (lilygo T-Display-S3) and I have a RYLR998 LoRa module connected to it. I use this as a remote start remote for my UTV vehicle.

This LoRa module is connected to the 3.3V rail and ground and the Tx and Rx were connected to GPIO18 and GPIO17 and everything was working great. A couple days later I found my battery was depleted and I recharged the battery but I could no longer communicate with LoRa module. I traced it to faulty GPIO pins. I don't know at this point if both were damaged because I just switch the Tx and Rx over to GPIO43 and GPIO44 and the communication was back up and running. At the time I had the RYLR998 connected temporarily to the esp32-s3 using bread board jumpers so I figured something shorted and didn't think much more about it. I soldered the tx and rx wires direcly to the gpio pins

Yesterday I used the remote all day and it worked great. This morning I got up and the battery voltage was at 2% The LoRa failed again to communicate and again the GPIO pins are the culprit.

there is nothing in the install manual for the LoRa module that states that I cannot connect my Tx and Rx pins from my RYLR998 module directly to the GPIO pins

I need advice
DG

[Sprite]

Strange. From what you're stating, you're not using anything out of spec on the design state of things: you're connecting 3.3V outputs to 3.3V-compatible inputs; that should operate forever without breaking.

[lichurbagan]

Search out brown-out spikes .... Your ESP32 GPIOs are likely getting damaged ..... when the battery drops very low.

Best practice is to place a 10–100 µF capacitor across 3.3 V and GND near the LoRa module.

I wouold recommend yo u to use 100–220 ohm resistor on TX/RX

Check this guide, will save you a lot of time: https://www.digikey.com/en/articles/pro ... lectronics