stm32 serial port interrupt receives a frame of data

I recently used the serial port of stm32. It was very tiring to interrupt the reception of characters one by one. I searched the Internet and found a good post. I would like to share it with you. The original post address is: http://www.51hei.com/bbs/dpj-39885-1.html

Thanks again to the original poster for sharing. For your convenience, I copied the original text here.

Today, let's talk about how to receive indefinite length byte data on the STM32 microcontroller. Since the STM32 microcontroller has an IDLE interrupt, this interrupt can be used to receive indefinite length byte data. Since the STM32 microcontroller belongs to an ARM microcontroller, the method in this article is also suitable for other ARM microcontrollers.
When does the IDLE interrupt occur?
IDLE is an interrupt that occurs after the serial port receives a frame of data. What is a frame of data? For example, if 1 byte is sent to the microcontroller at a time, or 8 bytes are sent at a time, these data sent at a time are called a frame of data, or a packet of data.
How to judge the end of a frame of data is the issue we are discussing today. Because this is used in many projects, because only after receiving a frame of data can you judge how many bytes have been received this time and whether the content of each byte meets the protocol requirements.
After reading the definition of the IDLE interrupt above, you will understand that an IDLE interrupt will be generated after a frame of data ends. This interrupt is really useful. It saves a lot of trouble in judgment.
How to configure the IDLE interrupt?
Let's configure the serial port IDLE interrupt.

This is the serial port CR1 register, where writing 1 to bit4 enables the IDLE interrupt, and writing 1 to bit5 enables the receive data interrupt. (Note: The corresponding register bits may be different for different series of STM32)
(What is the difference between the RXNE interrupt and the IDLE interrupt?
When 1 byte is received, an RXNE interrupt will be generated, and when a frame of data is received, an IDLE interrupt will be generated. For example, if 8 bytes are sent to the microcontroller at one time, 8 RXNE interrupts and 1 IDLE interrupt will be generated.)

This is the status register. When the serial port receives data, bit5 will automatically become 1. After receiving a frame of data, bit4 will become 1.
It should be noted that in the interrupt function, the corresponding bit needs to be cleared to 0, otherwise it will affect the next data reception. For example, the RXNE data receiving interrupt will clear the interrupt as long as a received byte is read out. The IDLE interrupt needs to be cleared using the ICR register if it is an F0 series microcontroller. If it is an F1 series microcontroller, the clearing method is "read the SR register first, then read the DR register".

1. /* Enable receive interrupt */  

2. USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);  

3. /* Enable idle interrupt */  

4. USART_ITConfig(USART1, USART_IT_IDLE, ENABLE);  

5. USART_Cmd(USART1, ENABLE);  

The key point is to enable the idle interrupt.

1. uint8_t ch[20];  

2. char i = 0;  

3. void USART1_IRQHandler(void)  

4. {  

5.   

6.     if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)//Received a byte  

7.     {     

8.         //ch = USART1->DR;  

9.             ch[i++] = USART_ReceiveData(USART1);  

10.       

11.     }   

12.     else if(USART_GetITStatus(USART1,USART_IT_IDLE) != RESET)//Received a frame of data  

13.     {  

14.         USART1->SR; //Read SR first  

15.         USART1->DR; // read DR again  

16.         i = 0;  

17.         printf("%s",ch);  

18.     }  

19.        

20. }