RF / IR Encoder / Decoder Chipset

RF600E

RF Evaluation Boards,

RF600D

Serial Data Format

Serial Data is sent as a stream of ASCII characters at 9.6K baud. The character format is 8 data bits

with 1 stop bit, no parity.

A serial data string is output every time a valid transmitter packet is received. Due to the nature of

the KeeLoq packet there will be a min gap between each serial data string of 150mSec.

10 characters are sent with the following format;

Output from SD1 pin

7

6

5

4

3

2

1

A(a)

$ 0D $0A

Line feed (last character)

Carriage return

Transmitter button information

with battery status

Transmitter serial number

10 bytes of data transmitted

The Transmitter Serial Number : is made up of 7 ASCII characters from the following group: 0 1 2

3 4 5 6 7 8 9 A B C D E F. The most significant serial number digit is transmitted first. This provides

a total of 28million possible serial numbers.

The KeeLoq Button Status is transmitted as an ASCII character in the range A to O or if the low battery

bit is asserted (encoder battery is low) then in the range a to o. KeeLoq data bits S0, S1, S2 and S3 then

make up the ASCII byte least significant bits D0, D1, D2 and D3.

If a single encoder button is pressed, say S0, then character A will be sent (or if low battery, a).

If encoder button S1 is pressed then B (or b) will be sent.

If S0 and S1 are both pressed simultaneously then character C (or c) will be sent.

If all KeeLoq encoder buttons are simultaneously pressed then character O (or o) will be sent.

Examination of the ASCII bit patterns shows that this allows single or multiple encoder button presses to

be decoded by the ASCII receiving device.

Examples of Serial Data output:

For a three button keyfob with serial number 2345678, the serial data output when encoder transmission

is decoded would be as follows:

If S1 is pressed: 2345678A (2345678a if the battery voltage in the transmitter is low)

If S2 is pressed: 2345678B (2345678b if the battery voltage in the transmitter is low)

If S1 and S2 are pressed together: 2345678C (2345678c if the battery voltage in the transmitter is low)

If S4 is pressed: 2345678H (2345678h if the battery voltage in the transmitter is low)

DS600-9 Sept ‘04

©2004 Reg. No. 227 4001, ENGLAND

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