Hein de Graaf

Important changes to forums and questions

All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.

8 years, 5 months ago.

STM32F103RB Ticker Crash

Hello all,

For the next program i'm using a STM32F103RB nucleo board. I'm trying to use a ticker to set an interrupt at a changing intervaltime. I want to use it to create an accurate acceleration with PWM. Therefor I need to attach and detach the ticker multiple times at high speeds. After a fixed amount of runs the program suddenly crashes. 

#include "mbed.h"

Serial pc(USBTX, USBRX);
DigitalOut myLed(LED1);
Ticker ledTicker;
bool ledBlink;
bool tickerTrigger;
int n;
        
void blink(){
    if(ledBlink == true){
        myLed =0;
        ledBlink = false;
        ledTicker.detach();
        tickerTrigger = false;
        }
    else if(ledBlink == false){
        myLed = 1;
        ledBlink = true;
        ledTicker.detach();
        tickerTrigger = false;
        }
    }

int main() {
        while(1) {
        if(tickerTrigger == false){
            n++;
            pc.printf("%i\r\n", n);
            tickerTrigger = true;
            ledTicker.attach_us(&blink, 250);
            }
    }
}

When i change the interval times, the program always crashes at the same points:

  • 250 us interval crashes at n = 14071
  • 500 us interval crashes at n = 13154
  • 1000 us interval crashes at n = 10305
  • 2000 us interval crashes at n = 14628
  • 3000 us interval crashes at n = 7097
  • 4000 us interval crashes at n = 3334
  • 5000 us interval crashes at n = 9562

The next error is reported: mbed assertation failed: _ops, file: /home/arm/mbed_jenkins/workspace/bm_wrap/172/mbed-os/BUILD/mbed/platform/Callback.h, line

When I delete the serial communication and/or counter n the program still crashes.

Thanks in advance!

1 Answer

Bill Bellis
8 years, 5 months ago.

Try something like this. Be sure to watch printf's when you have tight loops. This will generate a variable pulse. Might look into FastPWM instead depending on the accuracy of what you're really trying to do.

#include "mbed.h"
 
Serial pc(USBTX, USBRX);
DigitalOut myLed(LED1);
Timeout ledTicker;
bool ledBlink;
bool tickerTrigger;
int n;
int delay=250,inc=10;

        
void blink(){
    myLed = !ledBlink;
    ledBlink = !ledBlink;
    tickerTrigger = false;
    delay += inc;
    if(delay > 12345)inc=-inc;
    if(delay < 123)inc = -inc;
}
 
int main() {
        pc.baud(921600);
        while(1) {
        if(tickerTrigger == false){
            n++;
            pc.printf("%i\r\n", n);
            tickerTrigger = true;
            ledTicker.attach_us(&blink, delay);
            }
    }
}

Accepted Answer