3
Block Diagram of the Transmitter
Battery
Lithium
CR2032
LED
(red)
Microcontroller
1. Button
2. Button
Antenna
Antenna
RF-
transmitter
Modulator
UNLOCK
LOCK/
ANTI THEFT
Technical description RF transmitter
The RF-transmitter consists out of one tuning free colpitts oscillator stage which is frequency,
stabilized by a SAW resonator. The transmitter is modulated OOK (ON-Off Keying)
corresponding to the pulse code telegram.
The antenna is realized by a printed copper loop on the printed circuit board.
Microcontroller
Type:
4 Bit Microcontroller
The clock of the µC is generated by a RC-oscillator tuned to 2 MHz.
LED Indication
Data transmission is indicated by a red LED:
1 x flashing, when sending locking and theft protection signal
1 x flashing, when sending unlock signal
n x flashing, during transmitting signal for window lifter and/or sliding roof
Flashing frequency:
1 Hz
Duty cycle:
t
on
/t
off
= 1/3
Low Voltage Detection
If the battery voltage drops below 2.2 Volt a low voltage status is indicated.