What is a Keypad in Embedded Systems?

A keypad is an input device that is commonly used in embedded systems for data entry, password entry, and menu navigation. It consists of a set of buttons or keys arranged in a grid, where each key represents a unique input. The keys can be arranged in different configurations such as 3x4 or 4x4, depending on the specific application.

The keypad is connected to the microcontroller using various interfaces such as UART, I2C, SPI, or parallel port, depending on the specific keypad and microcontroller used. The microcontroller is programmed to read the keypad inputs and respond accordingly.

To read the keypad inputs, the microcontroller can be programmed using various techniques such as polling-based programming or interrupt-driven programming. In polling-based programming, the microcontroller continuously checks the status of each key on the keypad using a polling loop. The program reads the status of each key and processes the corresponding input if a key is pressed.

In interrupt-driven programming, the microcontroller is configured to trigger an interrupt whenever a key is pressed on the keypad. The interrupt service routine (ISR) then reads the input from the keypad and processes it accordingly.

Overall, the use of a keypad in an embedded system can provide a simple and intuitive user interface for data entry, password entry, and menu navigation, and can be implemented using various programming techniques depending on the specific requirements of the application.