Keypad

0

1

2

3

4

5

6

7

8 to 3

Encoder

I0

I1

I2

I3

I4

I5

I6

I7

O0

O1

O2

PIPO

Register

D0

D1

D2

Q0

Q1

Q2

Sensor

Synchronous 3 bit

Up / Down Counter

U/D

Clk

P0

P1

P2

3-bit

Comparator

A0

A1

A2

B0

B1

B2

trigger

555

Timer

555

Timer

7 segment

Display

"FULL"

7 segment

Display

"Space Available"