PIC16F627A Touchpad circuit

Posted on Dec 30, 2012

This board layout was created using the SOIC version of a PIC16F627A without drawing the usual schematic first. Most of the part values are etched on the Layout. The SIP resistor packs I used are 10k ohm, some experimentation with this value may be useful. Three pins are provided for 5 volts, ground, and TTL serial output on a standard 3pin/0.1 inch connection. The actual data from the touch sensors is quite erratic and requires some software processing.

PIC16F627A Touchpad circuit
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PIC16F627A Touchpad circuit - image 1
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Basically you create a pulse for each of the ports and read the data with the instruction following the pulse signlal rise. Then read the ports the same way looking for a gap of 0.1 seconds with no data detected. This does the 'debounce'. This results in fairly clean data capture from the sensors. Mostly, this is just an example of how to make your own control panels. The system can be extended to more inputs depending on how many your micro has. This design provides a telephone style layout and is programmed to send out values in 9600 baud ascii.

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