This module simplifies the use of 4×3 or 4×4 keypad dome matrix modules with Arduino/Raspberry Pi or other microcontrollers.
It is a small PCB that is placed between the keypad and Arduino/MCU with the following objectives:
1) use only 1 or 2 pins instead of 7-8 GPIO pins
2) simplify the programming by utilizing analog output or I2C or UART pots
3) reduce the code size by avoiding using libraries e.g. keypad.h
4) reduce processor load on the Arduino by off-loading this to the built-in processor
The board has 3 outputs that the user can select from:
1) Analog voltage – a particular voltage between 0 and 2.5V corresponds to a key pressed.
2) Serial/UART – any keypressed is transmitted at 9600 baud via the TX pin of the PCB – the data is a one character (1 byte ASCII)
3) I2C – query the device using I2C address 0x50 and the current key pressed is returned as a one bye ASCII char
Check out our Github page for example code.
User guide can be downloaded here: layadcircuits.com/ds/Smart-Keypad-Adapter/LayadCircuits_Product_LC075_SmartKP_UG_v1_0_0..pdf