Keypad phones, believe it or not, are still in use, and there is a surprising amount of variety to choose from. Some of the phones include 4G connectivity, cameras, and are built to last. If you're ...
The I2CKeyPad library implements the reading of a 4x4 keypad by means of a PCF8574. Smaller keypads, meaning less columns or rows (4x3) can be read with it too. Since 0.3.2 the library allows a 5x3, ...