Use MCU as simple TCP UART middle server (简单无线串口中间服务器). Tested on ESP32-C3 with MicroPython 1.24.0

tcpuart.py

# On Linux PC
# socat  pty,link=/tmp/ttyV0,raw  tcp:192.168.X.X:2000
# picocom /tmp/ttyV0
# esptool.py  --before no_reset --after no_reset --port /tmp/ttyV0
# rshell -p /tmp/ttyV0 --buffer-size 5000 

showTCP=False
showUART=False

try:
    tcp_buffersize
except:
    tcp_buffersize=6_000

try:
    custom_timeout
except NameError:
    custom_timeout = 0.1

import socket
import machine
from machine import UART
from machine import Pin
import errno
import time

p9 = Pin(9, mode=Pin.IN)

try:
    client_socket.close()
except:
    pass

try:
    server_socket.close()
except:
    pass

try:
    uart1.irq(None)
except:
    pass


uart1 = None
server_socket = None
client_socket = None

def stop_tcpuart():
    global uart1, server_socket, client_socket
    if client_socket:
        client_socket.close()
    if server_socket:
        server_socket.close()
    if uart1:
        uart1.irq(None)
        uart1.deinit()
        
def start_tcpuart(n=1):
    global uart1, server_socket, client_socket
    stop_tcpuart()
    if n == 1:
        tcpport = 2000
        txpin = 4
        rxpin = 5
    elif n == 2:
        tcpport = 2001
        txpin = 7
        rxpin = 6
    print(f"tcpport:{tcpport}  txpin:{txpin} rxpin:{rxpin}")

    uart1 = machine.UART(1, baudrate=115200, tx=txpin, rx=rxpin)

    addr = socket.getaddrinfo('0.0.0.0', tcpport)[0][-1]
    server_socket = socket.socket()
    server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server_socket.bind(addr)
    server_socket.listen(5)
    print('Listening on', addr)
    server_socket.setsockopt(socket.SOL_SOCKET, 20, accept_handler)
    
def accept_handler(server_socket):
    global uart1,  client_socket
    client_socket, client_addr = server_socket.accept()
    print('Client connected from', client_addr)
    client_socket.setblocking(False)
    client_socket.setsockopt(socket.SOL_SOCKET, 20, tcp_handler)
    uart1.irq( uart_rx_cb, UART.IRQ_RX)
    
def tcp_handler(client_socket):
    client_socket.settimeout(custom_timeout)
    data_tcprec = b''
    data_tcprec = client_socket.recv(tcp_buffersize)
    if len(data_tcprec) > 0:
        if showTCP:
            print(data_tcprec)
        uart1.write(data_tcprec)

def uart_rx_cb(*self):
    data = uart1.read()
    if data:
        if showUART:
            print(data)
        if client_socket:
            client_socket.send(data)