Digital Thermometer

Inspiration

Not much in the way of inspiration here. I wanted an excuse to learn how to use the DS1820 one-wire temperature sensors from Dallas Semi. So a thermometer seemed like a good thing to build. It is pretty straight forward. It reads the temp sensor then converts it to F before displaying it. The project was built on the proto-board and is still working fine.

Description

The circuit consists of a PIC16F84A that reads the DS1820 and displays it on a 4 digit seven segment display. A 74LS47, which is a BCD to 7-segment decoder TTL chip, was used to interface with the LED display because I had some on hand. Life being what it is could have interfaced the display straight to the display but the decoder chip made sense at the time. Oh, if you look at the code it is really poorly written. I did this project early in my micro experience which meant that I did not know any better.

Digital Thermometer

Here it is in all its glory. Not much to look at but served its purpose.

Digital Thermometer Back

I have learned that a lot of people will not show the back of there hand-wired circuit cards because they think that the soldering looks really bad. So here is a picture of my soldering job. It actually does not look that bad.