MCS3142 datasheet(13/57 Pages) MICROCHIP

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MCS3142 Dual KEELOQ® Encoder Wireless Remote

DS40001746A-page 12

 2014 Microchip Technology Inc.

2.2.2

Operation

The pre-programmed demo is used to demonstrate the operation of Microchip Remote

Keyless Entry (RKE) solutions. The demo highlights the capabilities of transmitting and

receiving secured data wirelessly. Two different methods, Classic KEELOQ and Ultimate

KEELOQ, are used in this demo.

The pre-programmed demonstration shows how to secure information during data

transmission.The transmitter sends out two types of packets. A Typical packet contains

the device serial number, button code, synchronization counter, timer (Ultimate

KEELOQ only) and various other parameters used in the decryption and validation

process. A Seed packet contains special data related to the encoder’s encryption key.

A Seed packet is sent infrequently, and only used when pairing a transmitter to a

receiver.

FIGURE 2-2:

MCS3142 KEY FOB

Pressing any one of the four buttons on the red key fob will start the encryption process

and eventual transmission of a KEELOQ packet. The LED will flash momentarily to

indicate a transmission.Table 2-1 describes the transmitter buttons and their functions.

The kit is configured to use the Secure Learn pairing mechanism. This requires the

encoders to transmit a special packet, called a Seed packet, with special information

the receiver needs to properly decrypt transmissions. This kit is configured to transmit

a Seed transmission with both buttons assigned to a particular encoder are pressed.

The pairing phase also requires a Typical transmission to complete the pairing process.

TABLE 2-1:

TRANSMITTER BUTTONS AND FUNCTIONS

Button Combination

Description

Button 1

Transmit a Classic KEELOQ® Typical Packet

Button 2

Transmit a Classic KEELOQ Typical Packet

Button 3

Transmit an Ultimate KEELOQ Typical Packet

Button 4

Transmit an Ultimate KEELOQ Typical Packet

Button 1 + Button 2 simultaneously

Transmit a Classic KEELOQ Seed Packet

Button 3 + Button 4 simultaneously

Transmit an Ultimate KEELOQ Typical Packet

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