Page 145 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

6.24 Resistive sensor
for Pot command

124

6.25 Schematic for Pot command

The value of scale needs to be determined experimentally. To
find a good scale value, set the resistive device under measure-
ment to its maximum resistance and read the var variable with
scale set to 255. Under these conditions, the value held in the
var variable will contain a reasonable value for scale.
A schematic of a basic circuit is shown in Fig. 6.25. For the resis-
tive sensor you can connect a 50K-ohm potentiometer. As the po-
tentiometer is varied, one of the LEDs will be lit depending upon
the value held in the variable B0. If the resistance value read is
above 125, LED 1 will light; if not, LED 2 will light.

The program for the PICBASIC compiler is as follows:
‘ PICBASIC Compiler ** reading resistance type sensors **
‘Photoresistor test program
Team LRN
Chapter six