Blog
21 Aug 2007
This is a simple 2 channel touch sensor using an AVR microcontroller (AT90S2313). This circuit can detect when you touch one of it’s inputs. According to author (Pontus Frössander):
“the basic idea is really simple. Make one pin output and another input. Connect a resistor between these pins. The resistor together with the human capacitance (about 100 pF) forms an RC network. The AVR set the output to low and then make a transition from 0V to +5V. 5 µs after this switch, the logic level at the input pin is sampled. If someone is touching the probe connected to the input pin, the capacitor (=human) will not be fully charged, and the input will be a digital 0 and vice versa.”
AVR based touch sensor - [Link]
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