[tribotec_ca88]

Originally Posted by MacFlightSierra

one loop of the controller is 26.2 millis - approx 38 loops per second. just add a variable to count till 38 and then reset it to zero

good luck/behatzla'ha

Hmm...i wouldn't recommend using the "approx 38 loops per second" method.

If you're looking for greater precision i recommend using the interrupt-driven timers. Our team is currently using Timer1 of the five PIC timers. Perhaps i'm not the best person to explain you exactly how they work but let me see if i can help...

First off, we created a function known as Init_timers(); (inside a .c file of our choice), which is called from inside User_Initialization() under user_routines.c.

Inside Init_timers we wrote the following code (to initialize and configure Timer1):

void Init_timers(void)
{
T1CONbits.T1CKPS0 = 1; // 1:8 Prescale (clock=1.25MHz/each tick=800ns)
T1CONbits.T1CKPS1 = 1;

TMR1H = 0x85; // sets Timer1's most significant byte
TMRIL = 0xED; // sets Timer1's least significant byte

T1CONbits.TMR1CS = 0; // Uses Internal clock

T1CONbits.T1OSCEN = 0; // Internal oscillator off

T1CONbits.RD16 = 1; // Timer1 operations done in 16-bit accesses

IPR1bits.TMR1IP = 0; // Sets interrupt as low priority

PIR1bits.TMR1IF = 0; // Overflow flag

PIE1bits.TMR1IE = 1; // Timer1 interrupt OK

INTCONbits.GIEL = 1; // Low priority interrupts OK

T1CONbits.TMR1ON = 1; // Timer1 set as on

}

Next you'll need to add a few things inside InterruptHandlerLow() inside user_routines_fast. This is a system function; I.E. when an interrupt is set, this function is immediately called by IFI's interrupt handler. You do not need to call it from anywhere in your code, however, you will need to include the following lines of code inside it. You'll notice this function already has several "IF" loops so all you have to do is add one more...

void InterruptHandlerLow ()
{
if[...]

else if (PIR1bits.TMR1IF && PIE1bits.TMR1IE) // checks to see if overflow has occured
{
PIR1bits.TMR1IF = 0; // resets Timer1 overflow
TMR1L = 0xED;
TMR1H = 0x85;
timer1_count++; // Timer1 counter incremented every 25ms
}

[...]

} // end of InterruptHandlerLow() function

Since I'm assuming you'll be working with timers inside your Autonomous code (as are we), all you'd have to do next is use "IF"s to compare the timer1_count variable. As was explained, the timer increments every 25ms, so if for example you wanted to have your robot execute a specific part of your code for 1s (=1000 ms), simple!: check if timer1_count is equivalent to 40...! For 2 seconds, 80, for 10 seconds, 400, etc etc etc...

This may not perhaps be the most accurate method but from our experiences it suited our specific needs...

Hope this helps...
any questions whatsoever, pm me...