Comments on: ESP32 UART Communication (Serial): Set Pins, Interfaces, Send and Receive Data (Arduino IDE)

By: Dr Quark

Dr Quark — Sat, 15 Mar 2025 17:06:23 +0000

It turns out that the TFT_eSPI.h library (or something linked in that library) prevents the UART (or maybe just IO16) from functioning on receive (Rx). Transmit (Tx) works fine. You can check the CYD hardware by removing the tri-color LED and the port3 connections to the CH340 and connecting IO16 and IO17 directly to port3. Then just do a loop-back test by connecting IO16 to IO17.

By: Dr Quark

Dr Quark — Fri, 14 Mar 2025 20:05:52 +0000

I know IO4, IO16, and IO17 work because they are connected to the LED in the unmodified CYD. I can see in the o’scope the proper 0.2v-3.3v serial data stream on IO16. I setup and started UART(2) using:

HardwareSerial SerialPort(2) ;
setup() {
Serial.begin(9600) ;
SerialPort.begin(9600, SERIAL_8N1, 16, 17);
…
…

When I reset the CYD, I occasionally get one SerialPort.available(), then nothing further.

By: Dr Quark

Dr Quark — Fri, 14 Mar 2025 19:53:38 +0000

In reply to Dr Quark.

I know IO4, IO16, and IO17 work because they are connected to the LED in the unmodified CYD. I can see the proper 0.2v-3.3v serial data stream on IO16. I setup and started UART(2) using:

HardwareSerial SerialPort(2) ;
setup() {
Serial.begin(9600) ;
SerialPort.begin(9600, SERIAL_8N1, 16, 17);
…
…

When I reset the CYD, I occasionally get one SerialPort.available(), then nothing further.

By: Dr Quark

Dr Quark — Tue, 04 Mar 2025 18:59:34 +0000

I’m trying to get two CYDs talking on UART(2). I’ve removed the tri-color led and connected the P3 port directly to pins 16 and 17, with no pullup resistors. I’ve cross-connected pins 16/17 and I see good serial output from pin 17, but pin 16 never gives me a Serial2.available(). I’ve used both units on the Tx side and the Rx side, just to make sure they both work when sending and to see if maybe one of the Rx sides of the UART is bad. Nope, Tx works on both, but Rx doesn’t work either way.

Is there something odd about UART(2) on the CYD?

By: syed furqaan

syed furqaan — Tue, 14 Jan 2025 12:40:36 +0000

I cant use gpio 01 and 03 on esp 32 for the following via usb to tll wotking if i use io 16 and 17

By: Sara Santos

Sara Santos — Mon, 23 Dec 2024 11:00:10 +0000

In reply to steven. Hi. Yes, you can set other pins. See the section"ESP32 Setting Custom UART Pins" Regards, Sara

By: steven

steven — Mon, 23 Dec 2024 04:50:46 +0000

i want to make a uart communication for my esp32 and gps but my esp32 module doesn’t have the 16 and 17 pin. can i use the other pin for example using pin 22 as a tx and pin 33 as an rx?

By: Bryant

Bryant — Tue, 26 Nov 2024 09:26:24 +0000

can I use esp1 to read the sensor and then the data is sent to esp2, because I have tried in arduino mega to esp32 that when reading the sensor it does not want to send, but when the sensor is not connected it wants to send data again….

By: Turbo_Nasty

Turbo_Nasty — Fri, 15 Nov 2024 17:35:14 +0000

I am having issues using the data received to do something. If the counter reaches ten for example I would like to serial.printing (“we reached ten”); I have tried a few different approaches using if(message == “10”) {} I have been unsuccessful so far. My goal is to send a color as a string “blue” and receive it as a string the perform a function to change LEDs. I am assuming the counter is sending the numbers as strings.

By: Talih5n@gmail.com

Talih5n@gmail.com — Sat, 26 Oct 2024 16:53:22 +0000

Merci tout est claire