3x4 matrix keypad - 5 V or 3,3 V

Product overview

• 3*4-key keypad in a matrix arrangement for inputs and control commands
• 12 individual keys in four columns and three rows
• Connection via eight signal lines, four for columns and four for rows
• 5 V or 3.3 V power supply
• With stable push buttons and Zener diodes for contact debouncing
• Wireless design, connection cable fitted with a pin header

Product description

This 3*4 matrix keypad is an input interface for embedded systems and microcontrollers. The twelve keys can be read via eight signal lines: four lines control the columns, while four sensor lines detect the rows. This significantly reduces the number of connection pins required compared with twelve separate inputs.

To ensure reliable inputs, Zener diodes for contact debouncing are integrated. The signal voltages are 5 V or 3.3 V, depending on the controller board used. No power supply is required during input because the switches are passive; connection is made via a fitted pin header.

For test purposes, such keypads are used in combination with an LCD and scrolling text as feedback in combination locks. Robot control boxes use a keypad for mode management and setting limit values. Test setups for alarm systems or access controls require inputs without a mains connection, which this keypad provides. Machine protection using the two-person principle can also be prototyped with a dual keypad matrix.

The keypad requires a driver routine in the microcontroller or a suitable library. The power supply must be matched to the logic level of the board; if necessary, a level shifter must be installed between the keypad and the board. The keys themselves are unencapsulated; embedding them in epoxy resin or using a separate cover depends on the design.

Safety notice

This keypad is intended exclusively for building prototypes and test and development setups. It is not intended for continuous use in safety circuits or household electrical circuits. Work on or immediately adjacent to electrical installations may only be carried out by a qualified electrician; if in doubt, consult a qualified electrician before commissioning.

Scope of delivery

• 1x 3x4 keypad / matrix - input keypad