USART_Communication_Tx_IT_Init Example Description

This example shows how to configure GPIO and USART peripheral to send characters asynchronously to HyperTerminal (PC) in Interrupt mode. This example is based on STM32C0xx USART LL API. Peripheral initialization is done using LL unitary services functions for optimization purpose (performance and size).

USART Peripheral is configured in asynchronous mode (115200 bauds, 8 data bit, 1 start bit, 1 stop bit, no parity). No HW flow control is used. GPIO associated to User push-button is linked with EXTI. Virtual Com port feature of STLINK could be used for UART communication between board and PC.

Example execution:

On press on push button , USART TX Empty interrupt is enabled.

First character of buffer to be transmitted is written into USART Transmit Data Register (TDR) in order to initialise transfer procedure.

When character is sent from TDR, a TXE interrupt occurs.

USART IRQ Handler routine is sending next character on USART Tx line.

IT will be raised until last byte is to be transmitted : Then, Transmit Complete (TC) interrupt is enabled instead of TX Empty (TXE).

On last byte transmission complete, LED1 is turned on.

In case of errors, LED1 is blinking (1sec period).

Program is written so that, any new press on User push-button will lead to new transmission of complete buffer.

Keywords

Connectivity, UART/USART, Asynchronous, RS-232, baud rate, Interrupt, HyperTerminal, Transmitter

Directory contents

- USART/USART_Communication_Tx_IT_Init/Inc/stm32c0xx_it.h          Interrupt handlers header file
- USART/USART_Communication_Tx_IT_Init/Inc/main.h                  Header for main.c module
- USART/USART_Communication_Tx_IT_Init/Inc/stm32_assert.h          Template file to include assert_failed function
- USART/USART_Communication_Tx_IT_Init/Src/stm32c0xx_it.c          Interrupt handlers
- USART/USART_Communication_Tx_IT_Init/Src/main.c                  Main program
- USART/USART_Communication_Tx_IT_Init/Src/system_stm32c0xx.c      STM32C0xx system source file

Hardware and Software environment

  • This example runs on STM32C071RBTx devices.

  • This example has been tested with NUCLEO-C071RB board and can be easily tailored to any other supported device and development board.

  • NUCLEO-C071RB Set-up:

    Connect USART1 TX/RX to respectively RX and TX pins of PC UART (could be done through a USB to UART adapter) :

    • Connect STM32 MCU board USART1 TX pin (GPIO PB.06 connected to pin 2 in CN9) to PC COM port RX signal
    • Connect STM32 MCU board USART1 RX pin (GPIO PB.07 connected to pin 1 in CN9) to PC COM port TX signal
    • Connect STM32 MCU board GND to PC COM port GND signal
  • Launch serial communication SW on PC (as HyperTerminal or TeraTerm) with proper configuration (115200 bauds, 8 bits data, 1 stop bit, no parity, no HW flow control).

  • Launch the program. Press on User push button on board to initiate data transfer.

How to use it ?

In order to make the program work, you must do the following :

  • Open your preferred toolchain
  • Rebuild all files and load your image into target memory
  • Run the example