The 1-Wire Key Pad
A tip on how to use one single pin on your microcontroller, to take different inputs form many buttons.
You can find the schematics and code files used in the video below.
/downloads/DipTrace%20Schematic%20-%201wire.pdf - The 1-Wire schematic
/downloads/DipTrace%20Schematic%20-%20multiwire.pdf - The multiwire schematic
/downloads/1wire.c - The C file
/downloads/HEX_1wire.hex - The HEX file (PIC16F616 Only)
Analog input is AN0, and the LEDs are on the digital outputs RC0 - RC3. The LED dropper resistors are 270 Ohm, and the values for the other resistors can be found in the video.