TCP Server

UiFlow2 Example

echo server

Open the cores3_tcp_server_example.m5f2 project in UiFlow2.

This example creates a TCP server that echoes the received data.

UiFlow2 Code Block:

Example output:

None

MicroPython Example

echo server

This example creates a TCP server that echoes the received data.

MicroPython Code Block:

# SPDX-FileCopyrightText: 2025 M5Stack Technology CO LTD
#
# SPDX-License-Identifier: MIT

import os, sys, io
import M5
from M5 import *
import network
import socket


label0 = None
label1 = None
label2 = None
label3 = None
label4 = None
label5 = None
label6 = None
label7 = None
label8 = None
label9 = None
title0 = None
wlan = None
tcps = None


con_info = None
con_sock = None
address = None
data = None


def setup():
    global \
        label0, \
        label1, \
        label2, \
        label3, \
        label4, \
        label5, \
        label6, \
        label7, \
        label8, \
        label9, \
        title0, \
        wlan, \
        tcps, \
        con_info, \
        con_sock, \
        address, \
        data

    M5.begin()
    Widgets.fillScreen(0x222222)
    label0 = Widgets.Label("Local IP:", 4, 32, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label1 = Widgets.Label("Local Port:", 4, 60, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label2 = Widgets.Label("Remote IP:", 4, 88, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label3 = Widgets.Label("Remote Port:", 4, 118, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label4 = Widgets.Label("Data:", 4, 144, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label5 = Widgets.Label("label5", 136, 32, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label6 = Widgets.Label("label6", 136, 60, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label7 = Widgets.Label("label7", 136, 88, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label8 = Widgets.Label("label8", 136, 118, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label9 = Widgets.Label("label9", 136, 144, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    title0 = Widgets.Title("TCP Server", 3, 0xFFFFFF, 0x0000FF, Widgets.FONTS.DejaVu24)

    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    tcps = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    tcps.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    tcps.bind(("0.0.0.0", 8001))
    tcps.listen(5)
    tcps.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    label5.setText(str(wlan.ifconfig()[0]))
    label6.setText(str("8001"))


def loop():
    global \
        label0, \
        label1, \
        label2, \
        label3, \
        label4, \
        label5, \
        label6, \
        label7, \
        label8, \
        label9, \
        title0, \
        wlan, \
        tcps, \
        con_info, \
        con_sock, \
        address, \
        data
    M5.update()
    con_info = tcps.accept()
    con_sock = con_info[0]
    address = con_info[1]
    label7.setText(str(address[0]))
    label8.setText(str(address[1]))
    while True:
        data = con_sock.recv(1024)
        label9.setText(str(data))
        con_sock.send(data)


if __name__ == "__main__":
    try:
        setup()
        while True:
            loop()
    except (Exception, KeyboardInterrupt) as e:
        try:
            from utility import print_error_msg

            print_error_msg(e)
        except ImportError:
            print("please update to latest firmware")

Example output:

None

API

socket.socket()

socket.bind(address)

socket.listen([backlog])

Create a socket object and bind it to an address.

Parameters:

address (tuple) – A tuple containing the server IP address and port number.
backlog (int) – The maximum number of queued connections. Default is 5.

Returns:

A socket object.

Return type:

socket.socket

UiFlow2 Code Block:

MicroPython Code Block:

import socket

tcps = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
tcps.bind(('0.0.0.0', 8001))
tcps.listen(5)

socket.close()

Close the socket connection.

UiFlow2 Code Block:

MicroPython Code Block:

tcps.close()

socket.accept()

Accept a connection. The socket must be bound to an address and listening for connections. The return value is a pair (conn, address) where conn is a new socket object usable to send and receive data on the connection, and address is the address bound to the socket on the other end of the connection.

Returns:: A tuple containing the client socket and the address of the client.
Return type:: tuple

UiFlow2 Code Block:

MicroPython Code Block:

client_socket, addr = tcps.accept()
print('Connected by', addr)

socket.recv(bufsize)

Receive data from the socket.

Parameters:: bufsize (int) – The maximum amount of data to be received at once.
Returns:: The received data.
Return type:: bytes

UiFlow2 Code Block:

MicroPython Code Block:

data = tcps.recv(1024)
print(data)

socket.read()

Read data from the socket.

Returns:: The received data.
Return type:: bytes

UiFlow2 Code Block:

MicroPython Code Block:

data = tcps.read()
print(data)

socket.send(data)

Send data to the socket. The socket must be connected to a remote socket.

Parameters:: data (bytes | str) – The data to be sent.
Returns:: The number of bytes sent.
Return type:: int

UiFlow2 Code Block:

MicroPython Code Block:

tcps.send(b'Hello, World!')
tcps.send('Hello, World!')

socket.write(data)

Write the buffer of bytes to the socket. This function will try to write all data to a socket (no “short writes”). This may be not possible with a non-blocking socket though, and returned value will be less than the length of buf.

Parameters:: data (bytes | str) – The data to be sent.
Returns:: The number of bytes sent.
Return type:: int

UiFlow2 Code Block:

MicroPython Code Block:

tcps.write(b'Hello, World!')
tcps.write('Hello, World!')

socket.setblocking(flag)

Set blocking or non-blocking mode of the socket: if flag is false, the socket is set to non-blocking, else to blocking mode.

This method is a shorthand for certain settimeout() calls:

sock.setblocking(True) is equivalent to sock.settimeout(None)
sock.setblocking(False) is equivalent to sock.settimeout(0)

param bool flag:

If True, the socket will be in blocking mode. If False, the socket will be in non-blocking mode.

return:

None

rtype:

None

UiFlow2 Code Block:

MicroPython Code Block:
tcps.setblocking(True)
tcps.setblocking(False)

socket.settimeout(timeout)

Set a timeout on blocking socket operations. The value argument can be a nonnegative floating point number expressing seconds, or None. If a non-zero value is given, subsequent socket operations will raise an OSError exception if the timeout period value has elapsed before the operation has completed. If zero is given, the socket is put in non-blocking mode. If None is given, the socket is put in blocking mode.

Parameters:: timeout (float) – The timeout value in seconds. If None, the socket is put in blocking mode.
Returns:: None
Return type:: None

UiFlow2 Code Block:

MicroPython Code Block:

tcps.settimeout(5)
tcps.settimeout(None)

socket.setsockopt(level, optname, value)

Set the value of the given socket option. The needed symbolic constants are defined in the socket module (SO_* etc.). The value can be an integer or a bytes-like object representing a buffer.

Parameters:

level (int) – The level at which the option is defined.
optname (int) – The name of the option to set.
value – The value to set for the option.

UiFlow2 Code Block:

MicroPython Code Block:

tcps.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 0)
tcps.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)