This repository contains several separate arduino format libraries, each one adding to the library Keypad external expansion port communication via an I2C (or Wire( )) port on the arduino ...

A keypad is one of the most commonly used input devices in microprocessor applications. In a standard keypad wired as an X-Y switch matrix, normally-open switches connect a row to a column when ...

The voltages and signal timings described below are dependent on the battery voltage and are probably also impacted by temperature. While the calculator runs on a 9 V battery, internally the logic ...