MCU serial port sends data frame

火辣西米秀

MCU serial port sends data frame [Copy link]

It is rare to see information about how to send a frame of data in an interrupt mode. If you send a data frame in a waiting mode, it will waste time for a high-speed microcontroller. The following is a method of sending a data frame in an interrupt mode. The operating platform uses 51 MCU.

　　First, define a data frame structure, which can be used as a global variable. All transmissions must pass through this structure:

　　//Structure

　　struct {

　　char busy_falg; //Busy flag, if set to 1 when sending data, that is, set to 1 at the beginning of sending and set to 0 at the end of sending

　　int index; //Index, pointing to the location where the array needs to be sent

　　int length; //The length of the entire data frame

　　char *buf; //Points to the data frame to be sent. It is recommended to be a global variable. Otherwise, once the sending starts, you must wait until the sending is completed, that is, judge that busy_flag is 0

　　} send_buf;

　　The function for sending data has a disadvantage, that is, it still needs to use while to detect whether the serial port is busy, but this is much better than taking up system time to send:

　　//Send a frame

　　void SendBuf(char *buf,int length)

　　{

　　while(busy_falg); //Check if the sending is busy, otherwise wait in a loop

　　send_buf.length = length;

　　send_buf.index = 0;

　　send_buf.buf = buf;

　　send_buf.busy_flag = 1;

　　SBUF = send_buf.buf[0]; //Write to SBUF, start sending, and then automatically enter interrupt sending

　　}

　　Serial port interrupt sending function, pay attention to setting the idle flag to avoid calling the same structure for multiple sending frames during multi-tasking:

　　void SerialInt() interrupt 4 //Serial port interrupt

　　{

　　if(RI == 1) //Serial port receiving

　　{

　　RI = 0;

　　}

　　else if(TI == 1) //Serial port sends

　　{

　　TI = 0;

　　send_buf.index++;

　　if(send_buf.index == send_buf.length)

　　{

　　send_buf.busy_falg = 0; //Sending is finished

　　return;

　　}

　　SBUF = send_buf.buf[send_buf.index]; //Continue to send the next

　　}

　　}

　　Serial port interrupt sending is as simple as this. Pay attention to the use of busy_flag and index.