MAX32660 MCU not outputting correct processor times - c

Question

I recently purchased a dev board for the max32660 MCU. I followed the instructions from the company's YouTube videos on how to set it up and got the example files working using the Eclipse IDE. I intend to use the time.h library to keep track of how long it takes to run various parts of my code, but whenever I try to printf() any clock_t type variables I just get back repeated 0.000000 values.
For the record: I am simply using my Arduino serial monitor to watch the signals come in from my USB port.
Maxim integrated youtube video:
https://www.youtube.com/watch?v=vpYBBYLkjTY&t=339s
Max32660 webpage
https://www.maximintegrated.com/en/products/microcontrollers/MAX32660.html
Code:
/***** Includes *****/
#include <stdio.h>
#include <stdint.h>
#include "mxc_device.h"
#include "led.h"
#include "board.h"
#include "mxc_delay.h"
#include "time.h"
/***** Definitions *****/
/***** Globals *****/
clock_t start;
clock_t end;
/***** Functions *****/
// *****************************************************************************
int main(void)
{
printf("Hello World!\n");
while (1) {
start = clock();
MXC_Delay(500000); //This part works fine
end = clock();
printf("%Lf\n", start); //I've tried many different versions of this
}
}
I've tried many different printf() configurations (%f, %lf, %ld, %s, %d, %i) and I cannot tell if the variables "start" and "end" are actually being saved as that value or if there is some problem with my serial port monitor reading the printf() statement, even though the "Hello World!" statement prints just fine.
I would expect to see any number besides 0.000000 being returned, particularly some integer that represents the number of clock cycles. I also expect that number to be somewhat low since the call to clock() is early in the script.

Answer 1

In most embedded standard libraries time() and clock() are not implemented or implemented as a "weak-link" stubs. You normally have to implement them yourself. In this case clock() and CLOCKS_PER_SEC are implementation dependent, you need to "re-targetting" the library to map this function to the hardware resources you choose to assign to that function. On a Cortex-M4 that would normally be a counter incremented in the SYSTICK interrupt at whatever rate (CLOCKS_PER_SEC) you choose for your platform.
You may already have support for SYSTICK and a system clock; in which case your clock() implementation might simply be a facade for that existing functionality.
Even if you had a working clock() the code:
printf("%Lf\n", start);
Is unlikely to produce a useful result in any case:
start is of type clock_t which is likely an alias for long, but certainly not long double.
Since any clock() implementation will be synchronous with whatever clock is used for MXC_Delay() the test simply measures itself!
end is unused so you are simply showin elapsed time, not the iteratuion time (that may be intended, in which case end is redundant). Perhaps you intended:
printf("%ld\n", (long)(end - start) ) ;
or possibly:
printf("%f\n", (double)(end - start) / CLOCKS_PER_SEC ) ;
I would doubt that on this target that long double is any larger than double in any event.