TCP mode as client passthrough mode under at command of ESP module

Ready to work

Prepare an ESP-F module of the DOITING brand or NODEMCU of the DOIT brand.


That is, VCC, EN connection 3.3v, GPIO15 GND grounding, module TX, RX connection serial port tool RX, TX, RST pin low level reset, unnecessary IO pin can be suspended, if you want to download the firmware in the module, please pull GPIO0 down processing (warm hint: if you buy ESP-01S/M/F1/F2, only need to connect VCC GND RX TX can work normally). If you buy an ESP-01 module, just connect CH-PD to VCC. Others can be connected according to the figure below (no IO port can not be connected). Please refer to the following instructions for product hardware design circuit.


1. 2 . Test

After completing the 1.1 connection, please check the circuit in detail and confirm that there is no problem. Open the debugging aid of serial port. The configuration mode is baud rate: 115200, data bit: 8 check bit: none stop bit: one flow control: none.

The configuration information is as follows:

To confirm that there is no problem, please press the RST reset key of K1 button (low level about 300m). Print the information as follows:

Display “read” to prove that the startup is normal.

Common Tools Download Connection:

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Frequently problems:

  1. Keyboard does not reflect

(1) Please check whether the power supply of the module is 3.3V/800ma.

(2) Please check whether TX and RX are in the wrong place.

(3) Check whether the port number is selected correctly and whether the port of serial debugging assistant is closed.

  1. The keys are all scrambled.

(1) Please confirm the baud rate of the module with the module manufacturer.

(2) Please check whether USB to TTL is compatible with module communication. What is recommended is a USB to TTL made of CH340 and CP2102 chips?

(3) Make sure that there is something wrong with the program in the module. (I’ll talk about how to burn firmware for modules later.)

Module TCP client transparent transmission mode

AT + CWMODE = 1 Set the module to STA mode. (Serial Assistant)

AT + CWLAP query nearby WIFI (serial port assistant)

AT + CWJAP = “123123”, “12345678” WIFI (serial port assistant) connected to the router

AT + CIFSR View the IP address assigned to the module by the router, such as (serial port assistant)

AT + CIPMUX = 0 set single connection (serial port assistant)

AT + CIPMODE = 1 Set transparent transmission mode (serial port assistant)

Network debugging assistant settings Connect the computer to the router, open the network debugging assistant, configure the TCP server port 8899, and check the IP assigned to the computer by the router

AT + CIPSTART = “TCP”, “”,8899 Connect to the TCP server (serial port assistant) established on the mobile phone

AT + CIPSEND starts sending data (serial port assistant)

Enter Send Mode (Serial Assistant) Send data (serial port assistant)

+++ Pay attention to exit transparent transmission and send directly. Cancel new line

Network debugging assistant sends data: Shenzhen Sibo Zhilian Technology Co., Ltd. (Network debugging assistant)


  • Note that transparent transmission can only be performed in single connection mode, so be sure to use it before setting up a connection (AT + CIPMUX = 0 to set single connection), but when the module is in server mode, multiple links must be used. Due to conflicts, the module Cannot do TCP transparent transmission when server mode is enabled!