Eduardo Iscar

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7 years, 4 months ago.

Error attaching interrupt to UART on LPC178 using mbed-os

Hi,

I am trying to reproduce example three from https://docs.mbed.com/docs/mbed-os-api-reference/en/5.2/APIs/interfaces/digital/Serial/ to attach a interrupt on receive to one of the serial ports on the LPC1768. Here is the code for reference:

The code

#include "mbed.h"

DigitalOut led1(LED1);
DigitalOut led2(LED2);

Serial pc(USBTX, USBRX);

void callback() {
    // Note: you need to actually read from the serial to clear the RX interrupt
    printf("%c\n", pc.getc());
    led2 = !led2;
}

int main() {
    pc.attach(&callback;);

    while (1) {
        led1 = !led1;
        wait(0.5);
    }
}

The code shown works fine if I am using mbed as the library. However, using the same code with mbed-os compiles properly, but it does not work. After uploading, LED1 blinks as expected. If I send a character to the serial port, it stops blinking, and I do no receive anything on the terminal.

I have been fighting with this for quite some time now, so any help will be greatly appreciated :)

Thanks a lot!

Hi everybody,

I have read your post because i have the same problem. I have replace Serial pc by RawSerial and my système doesn't work.

Do you have an idée to resolve the problem ?

posted by momo smith 02 Jun 2017

1 Answer

Jon Trinder
7 years, 4 months ago.

By coincidence Ive found myself in the same misery tonight but with a K64F...IF you make any progress let me know and I will post back here if I can make any progress.

Accepted Answer

Apparently, for some reason I don't know, the Serial library putc() and getc() methods do not work inside interrupt callbacks when using the RTOS. However, the library RawSerial does support them. Simply changing Serial pc(USBTX, USBRX); to RawSerial pc(USBTX, USBRX) solved the problem.

posted by Eduardo Iscar 01 Dec 2016

Hi everybody,

I have read your post because i have the same problem. I have replace Serial pc by RawSerial and my système doesn't work.

Do you have an idée to resolve the problem ?

posted by momo smith 02 Jun 2017