HCS512

DS40151D-page 4

© 2002 Microchip Technology Inc.

FIGURE 1-3:

BASIC OPERATION OF RECEIVER (DECODER)

NOTE: Circled numbers indicate the order of execution.

2.0

PIN ASSIGNMENT

PIN

Decoder

Function

Buffer

Description

1

LRNIN

I

TTL

Learn input - initiates learning, 10K pull-up required on input

2

LRNOUT

O

TTL

Learn output - indicates learning

3NC

—

TTL

Do not connect

4MCLR

I

ST

Master clear input

5

Ground

P

—

Ground connection

6S0

O

TTL

Switch 0

7S1

O

TTL

Switch 1

8S2

O

TTL

Switch 2

9S3

O

TTL

Switch 3

10

O

TTL

Battery low indication output

11

SLEEP

I

TTL

Connect to RFIN to allow wake-up from SLEEP

12

CLK

I/O

Clock in Programming mode and Synchronous mode

13

DATA

I/O

Data in Programming mode and Synchronous mode

14

P

—

Power connection

15

O

TTL

Oscillator out (test point)

16

I

ST

Oscillator in – recommended values 4.7 k

Ω and 22 pF

17

NC

—

—

18

RFIN

I

TTL

RF input from receiver

Note 1: P = power, I = in, O = out, and ST = Schmitt Trigger input.

2: Pin 12 and Pin 13 have a dual purpose. After RESET, these pins are used to determine if Programming

mode is selected in which case they are the clock and data lines. In normal operation, they are the clock

and data lines of the synchronous data output stream.

Button Press

Information

EEPROM Array

Manufacturer Code

32 Bits of

Encrypted Data

Serial Number

Received Information

Decrypted

Synchronization

Counter

Check for

Match

Sync Counter

Serial Number

Decryption

Algorithm

1

3

4

Check for

Match

2

Perform Function

Indicated by

button press

5

Crypt Key