Time and accuracy

KraZe_EyE

Hello again fellow stamp-inites!

My latest project for school is building a kiln for my glass blowing hobby; specifically slowly cooling down the temperature within the kiln over a long period of time.

I'm wondering how accurate the stamp stays to time say over an hour? (kiln cool down times are around 7-10 hours)
I have to check the temp every 30 seconds, check against known cool down time formula, update temp display, turn heating elements on/off, update LCD display then wait the rest of the time(pause) and do it again.

any idea how far off my timing would be after 10 hours?

I Saw there was a clock for sale in the parallax store; who's had good/bad experiences with that product?


Thanks,

-Matt

rixter

Matt,

It would seem that a programmatic timing loop in PBASIC using PAUSE or SLEEP commands would suffice in giving you 30 second intervals to perform your functions. Check more in HELP for the accuracy of these commands as there is some plus minus factor of about 1%. I guess it depends how accurate your timing must be. If absolute clock time is essential for some reason, I've found the DS1302 to work fine for that. I've used it in combination with a DS1620 to collect data center temperatures and feed the data to Stamp Plot. Of course you may have to use something other than the 1620 to get your temperature readings depending on the temperature ranges you are dealing with.

Rick

Tracy Allen

The DS1302 sold by Parallax would make your programming easier in the long run. It works very well to keep the time you can depend on, even as your program expands. If you don't have an external chip, you will have to retest the timing for every substantial program change you need to make, because the timing depends on a formula of program execution time + program dead time. With the clock chip, the program just has to read the clock and wait for the 30 seconds to roll over.

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Tracy Allen
www.emesystems.com