how to write 2 hours delay for timer in pic18f452

hi..i need help on writing the program for 2 hours of timer, where after 2 hours, it will reset back and return to 0. please help. im using pic18f452. the code can be in the assembly language which can run in mplab..but in c also can..

Have a look at the timer1 section of the 16F88 data sheet. It has example code to make a real time clock and will be easily modifiable to suit your needs.

Mike.

Pommie said:

Have a look at the timer1 section of the 16F88 data sheet. It has example code to make a real time clock and will be easily modifiable to suit your needs.

Mike.

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thank u...but i wonder if u can show me the example to write the code for 2 hours..because as far as i learn now..i've only learn to write the timer for few second...thats why ive got problem to write the code for 2 hours..

Hi,

The code you need depends on what you want to do now and in the future.

If you only want to do a 0 - 2 hours delay then reset things, a simple delay based timer will do.

If you want to do different times in the future or run other functions on the Pic at the same time then a Real Time Clock is the better option as Pommie suggested.

Perhaps post the code you have done for the ' timer for a few seconds' and we can point you in the right direction.
You need to specify the oscillator frequency you are using.

Step 1: use a counter to count seconds.

Step 2: once you can count seconds, count minutes

Finally step 3: Count hours.

use a variable for each counter. try writing the seconds program, and if you need help we'll help you. I'm going to write a clock program based on a 8 Mhz clock. I have it blinking a LED every 10 seconds based on a second counter variable. Eventually, I will add minutes and hours, but that is a low priority because I have changed my requirements for my current project that does not include a clock. When I add data logging capabilites, I'll add a clock.

I build'em like rmain1972: nested count loops until you're above the goal. I like using a very short interrupt every 100mS or so that only resets itself and increments a register.

The main program loop then checks the register for some rollover value (10=1S, 100=10S, etc), updates the next level counters then checks for the timed event value.