Then, add the interrupt service routine of UART DMA RX. HAL_UART_Receive_DMA(&huart3, RxBuffer, MAX_RX_BUF + 16) _HAL_UART_ENABLE_IT(&huart3, UART_IT_IDLE) Next is the code that enable UART IDLE Interrupt and activate UART DMA RX operation. RxBuf3 is user buffer to store the received data. RxBuffer is UART DMA RX buffer, rdPtr and wrPtr are pointer variables to pointing the start and end of valid data in RxBuffer. When UART IDLE Interrupt occurs, copy the remains in UART DMA RX buffer into user buffer.įirst, declare necessary variables as below.Then copy data received in UART DMA RX buffer into user buffer in the relevant interrupt service routine. HT and TC interrupts occur when Data arrives through UART DMA RX.The basic mechanism of UART DMA RX is as below. Next, check whether all Interrupts are “Enabled” in “NVIC Settings”.įor high speed UART data processing, set baudrate to 2Mbps.Īfter selecting “Generate Code”, you will find some codes are added in main.c, stmref1xx_it.c. As data may arrive anytime, it should be able to receive repeatedly without user’s operation. Then, set “DMA Request Settings->Mode” in “USART3_Rx” to “Circular”. UART3 Rx and UART4 Tx are connected and UART3 can receive the data which UART4 sent in DMA mode.įirst, select “Connectivity->USART3” on “Pinout & Configuration” section, and add “USART3_RX” in “Configuration->DMA Settings” section. In this example, I use UART3 and UART4 on STM32F103ZE MCU. So, when using UART DMA RX, monitoring HT, TC and UART IDLE interrupt is strongly recommended. In this case, we can solve the problem when we monitor UART IDLE Interrupt.

The problem is that TC interrupt does not occur when the received data is smaller than the designated size.

To use UART DMA RX, you should designate the size to read through UART DMa. In this case, using UART DMA RX can reduce MCU intervention because only HT and TC interrupts occur even though how big data comes in. When receiving a bulk data, using only interrupt may interfere MCU to process critical job due to a lot of interrupts. His tutorial is very helpful for us to understand the mechanism of UART DMA RX on STM32 MCU. I’ll explain how to use UART DMA RX here.įirst, thanks to Majerie Tilen and his tutorial and github repo regarding using UART DMA RX.

On the last post, I explained how to use UART DMA on STM32F103 MCU using HAL Library.

Stm32 ll uart interrupt example