Getting started with UART

Coming soon

This article explains what is UART and how to use it through examples

1. What is a universal asynchronous receiver transmitter (UART)

The universal synchronous/asynchronous receiver transmitter (USART/UART) offers a flexible means of Full-duplex data exchange with external equipment requiring an industry standard NRZ asynchronous serial data format. The USART offers a very wide range of baud rates using a programmable baud rate generator. It supports synchronous one-way communication and Half-duplex Single-wire communication, as well as multiprocessor communications. It also supports the LIN (Local Interconnect Network), Smartcard protocol and IrDA (Infrared Data Association) SIR ENDEC specifications and Modem operations (CTS/RTS). High speed data communication is possible by using the DMA (direct memory access) for multibuffer configuration. Also, the UART can be used with interrupt.
The main of this article is to describe the UART features and precisely:

• Simple UART communication
  
• UART with Interrupt
  
• UART with DMA
  

2. Objectives

The objectives of this wiki article are to know how to setup UART in STM32CubeIDE, how to generate code with STM32CubeIDE and how to use HAL functions.

2.1. Create the project in STM32CubeIDE

• File > New > STM32 Project in main panel.
  

In this example the NUCLEO-L476RG board is used.

• Select NUCLEO-L476RG board using Board Selector as shown in the below figure.
  

In case you haven't downloaded the STM32L476 Cube library, it will be downloaded automatically, it may take some time.

• Save the project.
  

• Initialize all peripherals with their default settings.
  

Answer “Yes” to initialize all peripherals with their default mode? Popup as below:

3. UART Configuration

• Choose the USART2 mode on Asynchronous mode.
  
• Set the parameter settings as shown in the below figure.
  

4. GPIO Configuration

To choose the correct GPIOs pins, it is necessary to refer to the datasheet and precisely Alternate function table.
For the STM32L476 USART communication is connected to PA2 for transmission and PA3 for reception as shown below.
File:STM32L476 datasheet table.png

For that, PA2 and PA3 are configured in alternate function mode.
File:GPIO configuration.png

5. Generate source code

Click “Ctrl+S” to generate the project

5.1. Simple UART Communication

5.1.1. Hardware preparation

Work in pairs boards, one will create transmitter and second receiver.
For that, the two boards are connected as follows:

• Rx board 1 connected with Tx board 2.
• Tx board 1 connected with Rx board 2.
• Connected the GND board 1 with GND board 2.

File:Hardware USART communication.png

5.1.2. HAL library workflow summary

File:HAL lib.png

• Transmit data
  

File:HAL transmit.png

• Receive data

File:HAL receive.png

5.1.4. Generate project and edit main.c

• Create data

Information

Insert your code to create data between /* USER CODE BEGIN 0 */ and /* USER CODE END 0 */ tags

/* USER CODE BEGIN 0 */
uint8_t data[]={0,1,2,3,4,5,6,7,8,9};
/* USER CODE END 0 */

• Transmit data

Information

Insert your code to transmit data between /* USER CODE BEGIN 3 */ and /* USER CODE END 3 */ tags

/* USER CODE BEGIN 3 */
  /* Infinite loop */
  while (1)
  {
    HAL_UART_Transmit(&huart2,data,10,1000);
  }
  /* USER CODE END 3 */

• Compile and flash

First of all, build your project
Then debug it when you used only NUCLEO-L476RG

• Or on Run button (to execute)
  

Connect the second Nucleo-L476RG.
Open a console emulator such as TeraTerm. Configure the console baud rate and data bits length. the COM Port name may differ on your PC for two Nucleo-L476 RG boards.
Configure the two Ports in this case COM4 and COM23 as shown in the below figures:

[[category:Getting_started_with_STM32_system_peripherals | 15]]