UART Communication Between NodeMCU and Arduino

First, I'm using MicroPython on the NodeMCU side.

Test 1:

Connections:

VIN     -    VIN
GND   -    GND
3          -    D3
2          -    D2

Arduino side code:

#include <SoftwareSerial.h>

SoftwareSerial ArduinoSerial(3, 2); // RX, TX

void setup() 

{

  Serial.begin(115200);

  ArduinoSerial.begin(4800);

}

void loop() 

{

  ArduinoSerial.write('abc');

  delay(100);

}

NudeMCU side:

from machine import 

UART uart = UART(1, 4800) 

uart.init(4800, bits=8, parity=None, stop=1) 

uart.read()

And...it didn't work.

There is UART 0 that is connected to the usb-serial converter and runs the repl.
There is UART 1 that only has a TX pin so I cannot receive data.

OSError: UART(1) can't read

There is UART 2 that doesn't seem to exist in micropython.

ValueError: UART(2) does not exist

So be it...Then we have two choices:

(1) use UART 1 but only sending data from NodeMCU to Arduino -- Test 2

(2) use UART 0 but not use the USB. -- Test 3

Both of the above tests are done using Arduino after flashing program to NodeMCU.

Test 2:

Test 3:

ref:

https://www.arduinoall.com/article/59/nodemcu-esp8266-esp8285-arduino-30-esp8266-nodemcu-%E0%B8%95%E0%B8%B4%E0%B8%94%E0%B8%95%E0%B9%88%E0%B8%AD-arduino-%E0%B9%81%E0%B8%9A%E0%B8%9A-serial

https://www.arduino.cc/en/Reference/SoftwareSerial

https://www.arduino.cc/en/Tutorial/SoftwareSerialExample

https://docs.micropython.org/en/latest/esp8266/library/machine.UART.html?highlight=uart

https://github.com/micropython/micropython/issues/2391

https://github.com/esp8266/Arduino/issues/482