Jaesung Park

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9 years, 3 months ago.

I'm trying to make a uart communication with nucleo f401re

Hello, I just started using nucleo f401re and mbed.

I'm trying to build a system to control servo motor which uses uart system.

Before making the final design i'm experimenting with Serial library to implement design but keeps failing.

Here's the code I made,

Serial Practice

#include "mbed.h"

DigitalOut myled(LED1);

Serial motor(USBTX, USBRX);

char* start = "10139444";
 
int main() {
    motor.format(8, Serial::None, 1);
    motor.baud(115200);
    while(1) {
        myled = 1;
        motor.printf(start);
        wait(1);
        myled = 0;
        motor.printf(start);
        wait(1);
    }
}

My question is, if i change the pins of motor led doesn't turn on. For example if I change the satement

Serial motor(USBTX, USBRX); to Serial motor(D1, D0); the code doesn't seem to run.

What't the reason for my failure?

Thanks in advance.

1 Answer

David Lowe
9 years, 3 months ago.

By default, Arduino header pins D0 & D1 are disconnected on all Nucleos. Instead, Serial2 Tx/Rx are routed to the ST-Link board to give debug output over USB to host PC.

Refer to http://developer.mbed.org/platforms/ST-Nucleo-F401RE/ and choose other pins for your motor connection.eg Serial1 Tx/Rx on D8/D2.

Full schematics of the Nucleos are in http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00105823.pdf

Accepted Answer

Thank you for your advice! It's been such a great help to me.

posted by Jaesung Park 25 Jan 2015