Hardware timers

[mitchf14]

I'm using "COUNT" command to count the number of pulses coming in but now i need to use the hardware timers. I want to count my pulse for 30 seconds, i was thinking of using TMR2 8 bit with prescaler. I'm using a PIC16F873 with a 20 Mhz crystal, could anyone let me know how to approach this.

[Bruce]

Are you trying to use a timer for the 30 second period, or trying to use a timer/counter?

[mitchf14]

I would just like to use the hardware timers, just to pause for 30 seconds so in the mean time my pic can keep running and keep collecting data for that 30 sec.


thanks

[Jerson]

I would think, you need a timer to keep count of the seconds. Any timer would do fine as long as you know how to extend it, in code, to count 1 second. This timer can then be further extended to count the 30 seconds interval you want.

Similarly, the pulses could come into the INT pin on your device and you could count the interrupt when it occurs.

Just ideas you could evaluate

[Bruce]

Why not just let the timer/counter count your pulses?

MyCount VAR WORD

TMR1L=0 ' clear the low byte
TMR1H=0 ' clear the high byte
T1CON = %00000011 ' set Timer1 up as a hardware counter

This counts rising edge pulses on RC0. The count is held in TMR1L and TMR1H.

Do whatever you need to collect other data for 30 seconds then just read the count.

MyCount.LowByte = TMR1L
MyCount.HighByte = TMR1H

You could set Timer1 to overflow, count overflows incrementing a variable, but it would be
a lot easier using a built-in hardware counter. And it doesn't interrupt whatever else your
program is doing. It counts in the background.

[Perrin`]

When I had to learn how to use timers, I used this thread.

This thread also happens to have EXACTLY what you want... a timer that counts down from 30.

http://www.picbasic.co.uk/forum/show...hlight=O_FLOWS

Sorry the link highlights O_FLOWS, I just happen to rememberthat variable so used it to find the thread.
Also wish I'd have read the forum sooner >.<;