STM86312

6/16

Figure 3: Key Matrix And Key-input Data Storage Ram

The key matrix is of 6 x 4 configuration, as shown below

The data of each key are stored as illustrated below, and are read by the appropriate read command,

starting from the least significant bit

LED PORT

Data are written to the LED port by a write command, starting from the least significant bit of the port.

When a bit of this port is 0, the corresponding LED lights; when the bit is 1, the LED goes off. The data of

bits 5 through 8 are ignored.

On power application, all the LEDs remain dark.

KEY1

KEY4 KEY1

KEY4

Seg1/KS1

Seg2/KS2

↓

Seg3/KS3

Seg4KS4

Seg5/KS5

Seg6/KS6

b0

b3 b4

b7

MSB

LSB

-

-

-

-

b3

b2

b1

b0

LED1

LED2

LED3

LED4

Don’t Care