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Analog Front End IC TMS37122 - Reference Guide August ’01
Figure 28: Passive Entry Wake Pattern Detection
After checking the Command the Microcomputer knows that a Passive Entry function is re-
quested (see Figure 29). The Challenge will be encrypted (ENCR), respectively the Rolling
Code will be determined depending on the system. Then the Microcomputer waits for the next
EOBA signal created by the Base Station, switching off the Transmitter. When this has hap-
pened, the UHF Transmitter is activated and the Response Telegram is sent to the Base Sta-
tion. There the Response is checked and the door is opened if valid.
The Microcomputer initializes the 3D-AFE after transmission of the Response with a short
negative pulse at WDEEN. The circuit returns to Standby Mode and is ready for next cycle.
EOBI
CLKI
0100 10000000000 0
0 1 00 1 00000000000
DATA
DATI
WAKE.
EOBA.
µC
WAKE
DELAY
CLKA/M
PS
PATTERN
PE
PATTERN
WAKEI
PASSIVE ENTRY WAKE PATTERNWAKE-UP
TIME
COMMAND + CHALLENGE
BASE
STATION
TXCT-
VWAKEA.
3DATIM01.DRW
COMMAND + CHALLENGE.
DATA
tWAIT
on
off
ID
DEVICE
WDEEN
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