6

PD16312

Key Matrix and Key-Input Data Storage RAM

The key matrix is made up of a 6

4 matrix, as shown below.

The data of each key is stored as illustrated below, and is read with the read command, starting from the least

significant bit.

Reading sequence

b0------------ b3

b4 ------------b7

LED Port

Data is written to the LED port with the write command, starting from the least port’s least significant bit. When a

bit of this port is 0, the corresponding LED lights; when the bit is 1, the LED truns off. The data of bits 5 through 8 are

ignored.

MSB

−−

−

−

b3

b2

b1

b0

Don't care

LSB

LED1

LED2

LED3

LED4

On power application, all LEDs are unlit.