Temperature reading

[Supernova]

Hello,

I would like to read a temperature like every 5 sec. I all ready know how to do the reading, but it's the part when I want to do an interrupt every 5 sec that i don't know how to do...

Can any one give me a tip?

Thanks

Jonathan

[Supernova]

oh by the way i'm using a PIC18f452 at 20MHZ if this can be of any use.

[RLScott]

[foodwatch]

I do this in my existing products. You can use something in the 18F family (I use an 18f4550 which might be overkill). Use the internal oscillator set to 1 or 4 mhz. Set the wdt timeout to either 1024 (about 4+ secs) or 2048 (about 9secs). I use the national LM61 analog temp chip. Create a simple loop, turn on wdt then sleep(). When you wake from sleep, read adc on the port you are connecting the lm61 to. Take the result, *.00488 (if using 10 bit ad) and the result is a float in millivolts. Subtract 600 from the result and the temp is in 10's of degrees c. The lm61 gives 600mv for 0 c so you can read -40c as 200mv (results always a positive number). The lm61 has its own internal regulator and will work from 3-10vdc. I run mine on the 5v to the cpu. I even run it off an output pin on the 4550 when I need to switch off the lm61 when running on batteries. Hope this gets you going in the right direction...

[foodwatch]

with the 18f452 you should be able to follow the above and get good results with 1/2 degree c resolution