Ian Weston / CPU_Usage Featured

CPU_Usage is a very lightweight library that can be easily incorporated into your application for testing performance. The reading is given as a percentage of CPU time which can be output however you like (serial, tft.. etc).

Dependents:   nucleo_encoder_stepper mbed-os-rest-api-V1-1

. If you are looking to measure the overall CPU Usage, call the working() function at the start of your code, and just call update() any time that you want to read the CPU usage value. Easy as that!

If you want to measure the CPU usage of a particular algorithm, place the working() function call before the code, and place the stopped() function call at the end. This limits the measuring purely to the usage of that code. calling update() will then then give you the percentage result.

When creating a CPU_Usage object you pass in 2x arguments. the first is a timer object, and the second is a ballast number (in seconds) precise to a single precision float value. This number can be though of as a smoothing number, play with this number to suit your application.

Hot Tips!:

- Use the library's delay() function instead of the built in mbed wait() function, this will exclude wait time from the usage value.

- If putting the device to sleep, place the stopped() function beforehand, and call the working() function after waking. This will exclude sleep time from CPU usage. ( will work on this for future so it will be handled automatically).

The API is so simple It almost needs no introduction. But documentation will follow soon. In the mean time here are two demos to get you started:

#include "mbed.h"
#include "CPU_Usage.h"

Serial pc(USBTX, USBRX);

Timer t;		                // create your timer object
CPU_Usage cpu(t, 1);	// create you CPU_Usage object

int main() {

   cpu.working();	// tell the CPU_Usage object that work has started
   uint8_t value = 0;

   while(1) {
                                        // HOT TIP!!!
       cpu.delay(0.25);	// use this in place of wait() to exclude waiting time from
			                // your usage value.

       value = cpu.update();	// retrieves the usage value

       pc.printf("CPU %i", value);	// send the value over serial.. if you want.
       }

}

#include "mbed.h"
#include "CPU_Usage.h"

Serial pc(USBTX, USBRX);

Timer t;
CPU_Usage cpu(t, 1);

// the code that you specifically want to measure
void function() {
    cpu.working();	// Tell the object work has started
    //
    // your awesome code here...
    //
    cpu.stopped();	// tell the object work has finished
}



int main() {

   uint8_t value = 0;

   while(1) {

       //
       // Do all your cool stuff,
       // calling function() when ever you want
       //

       value = cpu.update();           // retrieves the usage value

       pc.printf("CPU %i", value);   // send the value over serial.. if you want.

       }
}