1. To simplify decoding of a 4x4 keypad matrix, an 8-bit port was configured as inputs using internal pull-up and pull-down resistors the microprocessor.

Copied four-fold, this circuit joins the rows and columns of the 74HC595 to the keypad matrix. To scan across the four columns, the microcontroller performs an SPI transfer of the key value: 0x01.

Lower power consumption of 30 µA (typical) with keypad active, compared to 54 µA to 1000 µA available through alternative GPIO/keypad controllers 16-event FIFO simplifies reading of key, GPIO ...

Posted in Reverse Engineering, Tech Hacks Tagged button matrix, decoder, interface, keypad ...

Both keypad controllers support multiple, simultaneous key press detection and communicate presses and releases in a chronological order via a 16byte FIFO. In addition to the built in programmable ...

Analog Devices, Inc., has introduced a mobile I/O expander and QWERTY keypad controller with ambient light sensing for smart portable devices that require a large keypad matrix and expanded I/O lines.

You can expand the architecture to accommodate a keypad matrix as large as 8×10 keys by using more of the counter's outputs and wiring the Nth output to the counter's reset input. The keypad's rows ...

Using eight digital inputs, this circuit simplifies decoding of the common membrane 4x4 keypad matrix and eliminates the traditional requirement of scanning rows or columns. Any ...