who to implement HAL_GetTick()

to avoid compiler to remove code, declare time1 and time as volatile uint32_t

If the result of the calculation is not used, the compiler will remove the code...

I am not sure if I got your answer right but I did this

 time = HAL_GetTick();

    for (int i=0; i<100000000; i++)

      { i2cData[0]=0;

      }

      time1 = HAL_GetTick();

      time2 = time1 - time;

and it seams to be working I get time2 = 2778 (in watch in Keil)

my board is 180 Mhz. Any idea ho to translate it into microseconds or milliseconds ?

If I understand what you're asking, the HAL_GetTick() function returns a counter that is incremented by the SysTick, which in a default CubeMX project is 1000Hz, (each tick is 1ms).

volatile uint32_t time_ms, time1_ms, time2_ms; // to be sure

If you put in the variable name the unit and scale (if present), the answer is obvious...

SysTick_Handler() normally calls HAL_IncTick() to advance the count, but requires that the SysTick has higher priority than interrupt/callbacks that might have reliance on it actually advancing.

It looks like the old Keil bug. The debugger does not like non-local variables, even declared volatile.

So I have to note the variable's addresses and later use memory views.

Complained several times... but they treat debugger enhancement requests like ST treats Cube bugs here.

-- pa