Stephan Gerhardts

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9 years, 11 months ago.

stm32F746 serial connection 115200baud problem

Hello,

I am trying to connect my stm32F746 board to a serial device at 115200 baud and it doesen't work. The same connection with 9600 works fine. So I tryed to locate the problem with a simple terminal-connection in this way:

Serial uart(PF_7, PF_6);   // Tx, Rx
Serial pc(USBTX, USBRX);
.....
    pc.baud(115200);
    pc.format(8, SerialBase::None, 1);
    pc.printf("\n\n\r...start \n\r");
    
    uart.baud(115200);
    uart.format(8, SerialBase::Odd, 2);       //

....
    read = 0;
    while(1) {
        if((pc.readable()) && (read == 0)){
            // zeichen von Ubuntu
            c = pc.getc();
            if (c == 0x0d){             //send 3 bytes on enter
                uart.putc(0x8a);
                uart.putc(0xFF);
                uart.putc(0xAC);

                pc.printf("Enter an Terminal gesendet \n\r");
                read = 1;
                }

            }
        if ((uart.readable()) && (read ==1)){
            pc.printf("==> %#02x \n\r", uart.getc());
            pc.printf("==> %#02x \n\r", uart.getc());
            pc.printf("==> %#02x \n\r", uart.getc());
            read = 0;
            }
        }

This connection runs with 2 Computers and terminal programs. I try to send more than one byte in both directions, but more than one Byte could not be send without fault. The same thing works fine with 9600baud (9600uart / 115200pc) !

Could anyone help me?

Stephan

1 Answer

Bill Bellis
9 years, 11 months ago.

This is working correctly for me

#include "mbed.h"

DigitalOut myled(LED1);
Serial pc(USBTX,USBRX);
int main() {  
    int loop=1;
    pc.baud(115200);
    while(1) {
        myled = 1; // LED is ON
        wait(0.2); // 200 ms
        myled = 0; // LED is OFF
        wait(1.0); // 1 sec
        pc.printf("Hello %d",loop++);
    }
}

Sorry, but there are two Serial lines and "Serial uart(PF_7, PF_6);" causes the problem.

I need the uart connection for communication with a RS232 device at 115200 baud and 8 Databits, 2 Stopbits, parity Space. So I wrote a little program to test this connection with two terminal programs and the communication doesen't work with 115000. But with 9600 everything works fine.

posted by Stephan Gerhardts 27 Nov 2015