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This application note explains how to run a sample TCP server with the WiFi ESP Click card, from the FreeRTOS demo application.
1. Understanding WiFi ESP Click Interfaces
1.1. FreeRTOS WiFi ESP Click Implementation
The FreeRTOS BSP makes use of the STM32CubeH7 software component to provide a device driver for the WiFi ESP Click. The driver is configured (enabled / disabled) at the BSP build time, using the WIFIESP_MODULE_ENABLED
and HAL_UART_MODULE_ENABLED
configuration option, defined in the stm32h7xx_hal_conf.h
file.
1.2. FreeRTOS WiFi ESP Click C-Binding API
The WiFi ESP Click driver implements the following C-binding API:
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Code Block |
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typedef struct { uint8_t is_enabled; /* Enable flag */ uart_handler *uart; /* UART handle for communication with the WiFi ESP Click */ } wifiesp_handler; |
1.3. FreeRTOS WiFi ESP Click Macros
The WiFi ESP Click driver provides the following macros for AT instructions:
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Refer to ESP8266 AT Instruction Set for details about AT instructions.
2. Understanding TCP/IP support in FreeRTOS
2.1. FreeRTOS TCP/IP Support Implementation
The FreeRTOS BSP makes use of the WiFi ESP Click driver to provide TCP/IP support by sending AT instructions to the ESP8266 controller.
2.2. FreeRTOS TCP/IP Instructions Examples
The following are the examples of using the WiFi ESP Click driver to support TCP/IP in FreeRTOS:
Example | Description | Comments |
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Enable/disable multiple connections | The module responds OK if the mode set successfully and | |
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Start a TCP server with given port | The module responds OK if the server started successfully and | |
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Connect to a TCP server | The module responds OK if the server started successfully and | |
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Register UDP ports | The module responds | |
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Send data to the remote host via TCP or UDP | The module responds | |
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Close TCP connection or end UDP transmission | The module responds |
3. Understanding Sample TCP Server
3.1. Sample TCP Server Implementation
The FreeRTOS test application implements a separate thread called WiFi Thread, which provides a sample TCP server utilizing the WiFi ESP Click board.
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Read the SSID and passphrase from the U-Boot Environment variables
wifi_ssid
andwifi_passwd
.Initialize the WiFi ESP Click driver and start communications with the WiFi ESP Click board via UART.
Attempt to connect to the assigned AP (Access Point) and obtain an IP address via DCHCP.
Start the TCP server with the port 80, on the IP address obtained in the previous step, and run the endless loop that waits for connections. Having established a connection, it prints the received messages to the console and sends received data back to the connected client.
3.2. Sample TCP Server Sessions
Perform the following step-wise procedure, to validate the sample TCP server functionality:
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