Data Frame Transmission with timed rate

Are you using DSP/BIOS?  If so, you can just setup a timer to call your transmit function.

Yeah, that sounds plausible. One question though, I would be using one of the CPU timers for this purpose right? Also to make the timer call the Function, how exactly do i have to set it?

Janina

At what rate do you want to transmit the data?  The DSP/BIOS does use one of the CPU timers.  If the resolution of the BIOS timer is adequate, it is the only timer you need.

To call your transmit function using the BIOS configuration tool, right click on PRD - Periodic Function Manager under scheduling in the tree view on the left.  Select Insert PRD on the menu and give your timer a name.  It will then show up in the tree view and you can right click on it to set the properties like the period and the name of the function to call.

Well I was thinking of testing the first message at a rate of 1 s. But the CPU timer 2 is reserved specially for DSP/BIOS isnt it? Also this wouldnt be possible if i wouldnt be using DSP/BIOS. Couldnt you still use a Timer in that Case?

Out of Curiosity, What would be the aproach for timed message transmission without the use of DSP/BIOS?

You can still use a timer if you are not running DSP/BIOS, it just makes life easier as you don't have to do any work to configure the timer and write an interrupt routine.  Check out

the CpuTimer example in the register header files directory.  For the 2833x, it is here on my machine: C:\tidcs\c28\DSP2833x\v131\DSP2833x_examples\cpu_timer

if you are using CCSv4, that example is here in controlSUITE

John I Cant seem to find that example is my machine, could you maybe sen it to me ?

@Chris I'm using CCSv3.3

Thanks

install this and it will be in the directory that John is pointing to

Thank you so much you both I ve implemented it and works :)

Hey guys i have one more question. when i set the period of the time to higher that 15 s it doesnt work properly. The period stays in 15 s even though i set it to 60. You can see that the period is 60 s in teh registers but the messages are being transmitted with a period of 15 s . Why is that and how can i fix it??

Janina,

Can you post your timer init. code?

void InitCpuTimers(void)
{
    // CPU Timer 0
    // Initialize address pointers to respective timer registers:
    CpuTimer0.RegsAddr = &CpuTimer0Regs;
    // Initialize timer period to maximum:
    CpuTimer0Regs.PRD.all  = 0xFFFFFFFF;
    // Initialize pre-scale counter to divide by 1 (SYSCLKOUT):
    CpuTimer0Regs.TPR.all  = 0;
    CpuTimer0Regs.TPRH.all = 0;
    // Make sure timer is stopped:
    CpuTimer0Regs.TCR.bit.TSS = 1;
    // Reload all counter register with period value:
    CpuTimer0Regs.TCR.bit.TRB = 1;
    // Reset interrupt counters:
    CpuTimer0.InterruptCount = 0;


// CpuTimer2 is reserved for DSP BIOS & other RTOS
// Do not use this timer if you ever plan on integrating
// DSP-BIOS or another realtime OS.

    // Initialize address pointers to respective timer registers:
    CpuTimer1.RegsAddr = &CpuTimer1Regs;
    CpuTimer2.RegsAddr = &CpuTimer2Regs;
    // Initialize timer period to maximum:
    CpuTimer1Regs.PRD.all  = 0xFFFFFFFF;
    CpuTimer2Regs.PRD.all  = 0xFFFFFFFF;
    // Make sure timers are stopped:
    CpuTimer1Regs.TCR.bit.TSS = 1;
    CpuTimer2Regs.TCR.bit.TSS = 1;
    // Reload all counter register with period value:
    CpuTimer1Regs.TCR.bit.TRB = 1;
    CpuTimer2Regs.TCR.bit.TRB = 1;
    // Reset interrupt counters:
    CpuTimer1.InterruptCount = 0;
    CpuTimer2.InterruptCount = 0;

}

Hmmm, I don't see where you are initializing the PRD register for 60 seconds, can you enlighten me?  What's your sysclk freq?

well for the configuration of freq and perios im using the function

void ConfigCpuTimer(struct CPUTIMER_VARS *Timer, float Freq, float Period)
{
    Uint32  temp;

    // Initialize timer period:
    Timer->CPUFreqInMHz = Freq;
    Timer->PeriodInUSec = Period;
    temp = (long) (Freq * Period);
    Timer->RegsAddr->PRD.all = temp;

    // Set pre-scale counter to divide by 1 (SYSCLKOUT):
    Timer->RegsAddr->TPR.all  = 0;
    Timer->RegsAddr->TPRH.all  = 0;

    // Initialize timer control register:
    Timer->RegsAddr->TCR.bit.TSS = 1;      // 1 = Stop timer, 0 = Start/Restart Timer
    Timer->RegsAddr->TCR.bit.TRB = 1;      // 1 = reload timer
    Timer->RegsAddr->TCR.bit.SOFT = 1;
    Timer->RegsAddr->TCR.bit.FREE = 1;     // Timer Free Run
    Timer->RegsAddr->TCR.bit.TIE = 1;      // 0 = Disable/ 1 = Enable Timer Interrupt

    // Reset interrupt counter:
    Timer->InterruptCount = 0;
}

Which is then called :

ConfigCpuTimer(&CpuTimer2, 150, 60000000);

My Sysclk freq is 150 MHz

Thank you so much John i was thinking the same thing. I ve implementer a counter within the ISR and now the cyle time is the one i wanted.

Thanks Again!

Janina