Dual Digital Thermometer

Based on PIC16F877 and DS1820

A simple thermometer using DS1820 thermal probes that have a tolerance within 0.5°C.

I originally wanted a thermometer to monitor temperatures on my over clocked Video Card. Below are some pictures, schematic and PCB layout for the thermometer. The code I used wasn’t written by me. It was downloaded from http://www.warburtech.com/compilers/picbasic.pro/sample.code.htm (labeled “onewire.bas” near the bottom) and modified to display 2 temperatures instead of one temperature in Celsius and Fahrenheit. Some of the ports were also changed.`Here is the modified code:

Here is the code as download and the Circuitmaker200 PCB as download.

This is my thermometer with the LCD un-socketed. The three holes seen to the left of the 14pin SIP are for a potentiometer if the display you use requires a contrast control. My display did not have this function so I did not have to put a potentiometer on it. However all the connections are there, so if you need a pot for your display one just needs to be soldered in.

This is the picture again of the Thermometer without the display in place. This shot shows how the thermal probes and power are connected.

Here is the display running with probe 1 sitting next to it monitoring ambient house temperature, and the second probe left in the fridge for a couple minutes.

Copyright 2006 Barret R. de Visser

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