AS3930-BQFT austriamicrosystems, AS3930-BQFT Datasheet - Page 25

• Manufacturer Part Number: AS3930-BQFT
• Description: IC RF PROGRAM RECEIVER 16-QFN
• Manufacturer: austriamicrosystems

Specifications of AS3930-BQFT

• Rf Type: Read / Write
• Frequency: 110kHz ~ 150kHz
• Features: RSSI Equipped
• Package / Case: 16-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: AS3930-BQFTTR

AS3930
Data Sheet - D e t a i l e d D e s c r i p t i o n
Table 21. Preamble Requirements in Standard Mode, Scanning Mode and ON/OFF Mode
8.7.3 Single Pattern Detection (Manchester decoder enabled)
The
R1<3>=1) for a 125 kHz carrier frequency. The initial carrier burst has to be at least 42 Manchester symbols long and has to be followed by a
separation bit (one bit of no-carrier). The carrier burst must be followed by a minimum 4 Manchester symbol preamble (10101010) and the
pattern stored in the R5<7:0> and R6<7:0>. The preamble can only be made up by integer Manchester symbol and the preamble duration
together with the pattern should not be longer than 40 bits. If the pattern is correct the signal on the WAKE pin is set to high, the data are
internally decoded and the Manchester clock is recovered. To set the AS3930 back to listening mode the direct command clear_false or the time
out option (R7<7:5>) can be used.
In case the On/OFF mode is enabled the Manchester decoder can not be used
Figure 19. Wakeup Protocol Overview with Single Pattern Detection (Manchester decoder enabled)
8.8 False Wakeup Register
The wakeup strategy in the AS3930 is based on 2 steps:
If there is a disturber or noise capable to overcome the first step (frequency detection) without producing a valid pattern, then a false wakeup call
happens.Each time this event is recognized a counter is incremented by one and the respective counter value is stored in a memory cell (false
wakeup register). Thus, the microcontroller can periodically look at the false wakeup register, to get a feeling how noisy the surrounding
environment is and can then react accordingly (e.g. reducing the gain of the LNA during frequency detection, set the AS3930 temporarily to
power down etc.), as shown in the
environment and thus avoid false wakeup events.
www.austriamicrosystems.com/AS3930
Bit rate (bit/s)
Figure 19
1. Frequency Detection: in this phase the frequency of the received signal is checked.
2. Pattern Correlation: here the pattern is demodulated and checked whether it corresponds to the valid one.
1212
1092
1056
1024
1170
1128
shows the wakeup protocol in case both the pattern correlation and the Manchester decoder are enabled (R1<1>=1 and
Maximum duration of the carrier burst in Standard
Figure
Mode and Scanning Mode (ms)
20. The false wakeup counter is a useful tool to quickly adapt the system to any changes in the noise
13.20
13.67
14.18
14.65
15.15
15.62
Revision 1.0
.
Maximum duration of the carrier burst in ON/OFF Mode
13.20
13.67
14.18
14.65
15.15
15.62
(ms)
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