STm32F401RE: FPU not working

[FAJOL.1]

Hi guys,

I really need your help.

I'm trying to divide two numbers.. But the result is still 0. Analyzind the disassembling the commands are not those of FPU unit. I enable the FPU in the  Properties/MCU Setting.

Here the simple code:

uint32_t A = __HAL_TIM_GET_CLOCKDIVISION(&htim3)+1; // result is 1

uint32_t B = HAL_RCC_GetPCLK2Freq(); // result is 84000000

float D = A/B; // result is 0

double E = A / B; // result is 0

long double F = A / B; // result is 0

double G = 1 / 5; // result is 0

uint32_t H = 10/3; // result is 3

double I = 10/3; // result is 3

Any ideas

Thanks

[AScha.3 · Accepted solution]

Hi,

You have to learn about C , not the cpu is the problem here.

If you want float, you have to use float - or "tell" the compiler about your desire : casting .

+ double is not calculated in hardware, on F401 is just (single) float unit.

try :

float D = (float) A/B;

float D = (float) A/ (float) B;

read...ie:

https://www.tutorialspoint.com/cprogramming/c_type_casting.htm

[Andrew Neil]

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[FAJOL.1]

Thanks