Hardfault due to coprocessor access?

[nrbrook]

I received the hardfault in the following image.

The function at the address 0x00028C44 is:

static uint32_t app_timer_ms(uint32_t ticks)
{
    // eg. (7 + 1) * 1000 / 32768
    //   = 8000 / 32768
    //   = 0.24414062
    float numerator = ((float)APP_TIMER_CONFIG_RTC_FREQUENCY + 1.0f) * 1000.0f;
    float denominator = (float)APP_TIMER_CLOCK_FREQ;
    float ms_per_tick = numerator / denominator;

    uint32_t ms = ms_per_tick * ticks;

    return ms;
}

The hardfault did not occur again after resetting. I'm not sure why this would occur. Could it be something to do with the FPU?

[Hung Bui]

Hi Nick, 

I'm not sure what could be wrong here. But have you checked the FPU is used ? 
Does it only occur on the first run after programming and not when after you reset ? 

If you change the function to use only return dummy ms do you still have the same issue ? 

[nrbrook]

How can I check if FPU is used? It should be I think. This problem occurred for someone else not me, but I think it occurred the first time the above code was run after DFU. It did not occur after reset.

[Hung Bui]

Hi Nick, 

You can check that in the project setting, for example here is in Segger Embedded Studio:

Or here is in Keil: 

Please check that configuration in the application as well as in the bootloader project.