I2C Capacitive Keypad with Mpr121 12 Touch Buttons Overview This capacitive keypad uses the Mpr121 touch controller and twelve touch panels to provide a simple, lowprofile keyboard with I2C output. The board includes four mounting holes for secure installation in panels or enclosures. It is designed as a direct replacement for traditional mechanical buttons where a modern touch interface is preferred. Key benefits Simple integration: I2C output provides a two wire interface that is easy to connect to microcontrollers and single board computers with I2C support. Reduced wiring and host load: The Mpr121 handles touch scanning, delivering key states to the host and reducing software complexity. Durable replacement for mechanical buttons: Capacitive touch elements remove mechanical wear points and simplify enclosure design. Secure mounting: Four mounting holes on the PCB allow reliable attachment to panels, boxes, or custom housings. Compact, user friendly layout: Twelve clearly spaced touch pads give straightforward, familiar keypad operation. Important attributes Controller: Mpr121 capacitive touch controller. Inputs: 12 touch panels for individual key detection. Interface: I2C digital output for direct connection to I2C capable hosts. Mounting: Four PCB mounting holes for secure installation. Form factor: Compact PCB keypad suitable for panel integration or prototype boards. Compatibility and requirements Works with any host that supports I2C communication and can read simple key state registers. Host software needs an I2C driver and the ability to poll or read touch status from the Mpr121. No mechanical switches required on the host side. Practical use scenarios Home automation control panel: mechanical buttons with a slim capacitive keypad for lighting, climate, or media control panels. Embedded prototypes and products: Add a low profile input method to microcontroller or single board computer projects without developing custom touch firmware. Industrial or kiosk interfaces: Install in enclosures where sealed surfaces and reduced maintenance are desirable, using the mounting holes for robust attachment. Installation notes Mount the PCB using the four provided holes and appropriate fasteners for your enclosure. Connect SDA and SCL lines to the host I2C bus and supply the appropriate power and ground. Consult Mpr121 documentation or existing I2C libraries for required register reads and configuration options. This I2C capacitive keypad provides a straightforward, space saving way to traditional buttons with a 12 key touch interface driven by the Mpr121 and accessible over I2C.