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Bots /The Ultimate Palm Robot/ Mukhar & Johnson / 222880-6 / Chapter 9

Chapter 9 Sensors and Enhancements 245

Using a Temperature Sensor
Another sensor that we tried with the PPRK is the LM34DZ temperature
sensor. This sensor is made by national Semiconductor. A simple search of
the web should turn up several suppliers. We found some of these at
www.allelectronics.com and www.pigselectronics.com.
As with the photo detectors, the LM34DZ can be directly connected to either
the SV203 or the BrainStem. The LM34DZ has three leads: one for Vcc, one for
Vo, and one for the GND. These are connected directly to the appropriate leads
on either the SV203 or the BrainStem.

After the sensor is connected to the SV203 or the BrainStem, you can read it
using the same techniques we’ve already discussed. The LM34DZ changes its
output voltage based on the temperature it senses. For each degree Fahrenheit
that is sensed, the sensor outputs 10 millivolts. For example, if the tempera-
ture is 65 degrees, the sensor will output .65 volts; a temperature of 75 degrees
will cause the sensor to output .75 volts. The A/D ports of the controller will
convert the voltage to a digital value between 0 and 255.

Other Sensors

At this point, attaching other sensors to either the SV203 or the BrainStem con-
trollers should be a simple matterforyou.IfthesensoralreadyhaspinsforVccof
5 volts, a GND, and an output voltage line Vo, you can attach it directly to either
controllerusingthesametechniqueswe’veusedinthischapter.Ifyouneedmore
information, one of the best resources we’ve found for modifying the PPRK with
additional sensors is Roberts Gadgets and Gizmos at www.bpesolutions.com/
gadgets.ws/gproject3.html.

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Monday, May 12, 2003 4:33:43 PM