I have a project that needs 3 serial ports on my ESP32 Dev 38-pin MCU. Two of them are for Nextion touch displays and the other is for a GPS. The problem from what I understand is that the ESP32 has 3 hardware serial ports of which only 2 can be used. GPIO 1 and 3 can not be connected to the display during upload and the software serial that is in Arduino IDE 2.0.4 is not compatible with an ESP32. Can anyone tell me how I can use 3 serial ports?


  • use ota to upload sketches, it's faster, safer, and more flexible anyway. you can also use a software serial, mos def.
    – dandavis
    Mar 8 at 6:18
  • It's easy to remap any of the ESP32 serial port pins to other pins, so you're not bound to the standard pinout.
    – StarCat
    Mar 8 at 10:48

1 Answer 1


Welcome Richard, your question is interesting and a common problem in the Arduino arena. I simply use a SPI or I2C board that outputs RS232. I stumbled across them a few years back and used several, they worked great. I do not remember what they were called but here is a link to one of the many that are available: "https://andino.systems/extensions/rs232"This was the first search term I used: arduino SPI to RS232 module". Here is another link for the Pi: "https://forums.raspberrypi.com//viewtopic.php?t=146908&p=1083915#p1024636"

  • Gil, this is not a discussion forum. We don't write answer for the poster, but for the problem. Put only solutions in the answer box. Please take the Tour arduino.stackexchange.com/tour
    – Juraj
    Mar 9 at 6:38

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