This discussion has been locked.

You can no longer post new replies to this discussion. If you have a question you can start a new discussion

Can't use float in the sourcecode?

Max K over 10 years ago

Hello,

I don't know, why I can't use float in my timer_callback function.

If I want to use a float variable in my timer callback function, the timer stops always after one round. Although I use a periodic timer. Do anyone know, how can I resolve this problem?

0 Max K over 10 years ago

The sourcecode is written in uVision MDK-Lite Version 5.11.1.0.
Cancel
Vote up 0 Vote down

Cancel
0 Westonsupermare Pier over 10 years ago in reply to Max K

Using a board or processor any of us might be familiar with? Is it faulting?
Cancel
Vote up 0 Vote down

Cancel
0 Max K over 10 years ago in reply to Westonsupermare Pier

I use a MCB4300.
Cancel
Vote up 0 Vote down

Cancel

0 J. Oswald over 10 years ago in reply to Max K

Have you thought of initilizing the FPU ?
In the LPC_Open library code (fpu_init.c) their is a function:

/* Early initialization of the FPU */
void fpuInit(void)
{
    // from arm trm manual:
    //                ; CPACR is located at address 0xE000ED88
    //                LDR.W R0, =0xE000ED88
    //                ; Read CPACR
    //                LDR R1, [R0]
    //                ; Set bits 20-23 to enable CP10 and CP11 coprocessors
    //                ORR R1, R1, #(0xF << 20)
    //                ; Write back the modified value to the CPACR
    //                STR R1, [R0]

    volatile uint32_t *regCpacr = (uint32_t *) LPC_CPACR;
    volatile uint32_t *regMvfr0 = (uint32_t *) SCB_MVFR0;
    volatile uint32_t *regMvfr1 = (uint32_t *) SCB_MVFR1;
    volatile uint32_t Cpacr;
    volatile uint32_t Mvfr0;
    volatile uint32_t Mvfr1;
    char vfpPresent = 0;

    Mvfr0 = *regMvfr0;
    Mvfr1 = *regMvfr1;

    vfpPresent = ((SCB_MVFR0_RESET == Mvfr0) && (SCB_MVFR1_RESET == Mvfr1));

    if (vfpPresent) {
        Cpacr = *regCpacr;
        Cpacr |= (0xF << 20);
        *regCpacr = Cpacr;  // enable CP10 and CP11 for full access
    }

}