AAN124

Interface the Athena to a DS1620 Thermometer

  By Michael Simpson

The DS1620 is a very accurate thermometer.   It is accurate to .5 Celsius.  

Features

• Requires no external components

• Supply voltage range covers 2.7v to 5.5v

• Measures temperatures from -55°C to +125°C in .5°C increments and -67°F to +257°F in .9°F increments

• Converts temperature to to digital in 1 second (max)

• 3 Wire Interface

Since the Athena has only 8 bit variables we will stick to 0 - 125 degrees in 1 degree increments.

 

Hookup

 

This program takes does two shiftout commands.  The first setsup the DS1620 and the second tells the DS1620 we want to read the temperature.  The program then reads the temperature.  We will through away the .5 bit by dividing the result by 2

Program 1 download it here

'DS1620 Demo
   dim temp

   const dat 0
   const clk 1
   const rst 2

   output clk
   output rst
   low rst
   high clk

loop:
   gosub gettemp
   print temp
   pause 100
   goto loop


gettemp:
   high rst
   pauseus 50
   output dat
   shiftout dat,clk,8,238
   low rst

   high rst
   pauseus 50
   output dat

   shiftout dat,clk,8,170
   input dat
   shiftin dat,clk,8,temp
   low rst

   temp = temp/2
   return

 

Parts

Easy RS232 Driver  

Athena

DS1620

 

7.5V AC Adapter

9 Pin Cable

Breadboard and Wire Kit

Breadboard Regulator