A weblog focused on interesting circuits, ideas, schematics and other information about microelectronics and microcontrollers.
Two touch sensors based on an ARM microcontroller.
The first one is the piece based on AT90S2313 with two sensing plates and two switches. Author (Pontus Frössander) says: "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."
The second one is ftom the well known ELM-CHAN pages. It implements the capacitive touch sensor (the same principle as the first one), but it provides 8 sensors and it's based on ATTiny2313.