ESP UART using Arduino IDE

Many projects have me finding myself in a position where I cannot find all of the information in one place to solve what should be a simple problem.

I’m on Manjaro Linux trying to use the Arduino IDE to create a usb UART interface from an esp32 devkit I have in the drawer. Before getting started, we needed to find a board support package for the ESP32 to shove into the Arduino IDE.

1. With Arduino IDE open, press Ctrl+,
2. Under Additional Board Manager URLs add https://espressif.github.io/arduino-esp32/package_esp32_dev_index.json
3. Open Tools > Board > Board manager
4. Search Esp32 and install Arduino ESP32 Boards
5. Select an Arduino esp32 option from the boards dropdown before compiling or flashing

Upon compilation it was determined that there was no serial module available for flashig phase.

import serial
ImportError: No module named serial

As it turns out, I did not have pip, either. Open a terminal and input:

sudo pacman -S python-pip
pip install pyserial

Serial port /dev/ttyUSB0
File "/home/YOURUSERHERE/.local/lib/python3.10/site-packages/serial/serialposix.py", line 322, in open self.fd = os.open(self.portstr, os.O_RDWR | os.O_NOCTTY | os.O_NONBLOCK)
PermissionError: [Errno 13] Permission denied: '/dev/ttyUSB0'

Permissions can be checked in your terminal using:

ls -lash /dev/tty*

in this case, I needed to modify my user permissions in the group uucp to access serial devices.

sudo usermod -aG YOURUSERHERE uucp

To remove users from a group if you wish to do so after flashing:

sudo gpasswd -d YOURUSERHERE uucp

Below pins 2 and 4 are being used. Pin 2 for receive and pin 4 for transmit.
A substantial amount of help came from this source

Using any GPIO pins as Rx / Tx:

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#define UART_RX_PIN 2 // GPIO2
#define UART_TX_PIN 4 // GPIO4
void setup() {
//Serial connects to the computer
    Serial.begin(115200);
//Serial2 is the hardware UART port that connects to the external circuit.
//115200 is the baudrate expected for UART.
    Serial2.begin(115200, SERIAL_8N1,
    UART_RX_PIN,
    UART_TX_PIN);
    }

    void loop() {
        //Forward bytes incoming via PC serial
        while (Serial.available() > 0) {
        Serial2.write(Serial.read());
    }
    //Forward bytes incoming via UART serial
    while (Serial2.available() > 0) {
        Serial.write(Serial2.read());
    }
}

Screen command for setting baudrate on your TTY port:

screen /dev/ttyUSB0 115200