PIC12F635/PIC16F636/639
11.29 Demodulator
The demodulator recovers the modulation data from
the received signal, containing carrier plus data, by
appropriate envelope detection. The demodulator has
a fast rise (charge) time (TDR) and a fall time (TDF)
appropriate to an envelope of input signal (see
Section 15.0 “Electrical Specifications” for TDR
and TDF specifications). The demodulator contains
the full-wave rectifier, low-pass filter, peak detector
and data slicer.
FIGURE 11-9:
DEMODULATOR CHARGE AND DISCHARGE
Signal into LC input pins
Full-wave Rectifier output
Data Slicer output
(demodulator output)
TDR
TDF
For a clean data output or to save operating power, the
input channels can be individually enabled or disabled. If
more than one channel is enabled, the output is the sum
of each output of all enabled channels. There will be no
valid output if all three channels are disabled. When the
demodulated output is selected, the output is available in
two different conditions depending on how the options of
Configuration Register 0 (Register 11-1) are set: Output
Enable Filter is disabled or enabled.
11.30 Power-On Reset
This circuit remains in a Reset state until a sufficient
supply voltage is applied to the AFE. The Reset
releases when the supply is sufficient for correct AFE
operation, nominally VPOR of AFE.
The Configuration registers are all cleared on a
Power-on Reset. As the Configuration registers are
protected by odd row and column parity, the ALERT pin
will be pulled down – indicating to the microcontroller
section that the AFE configuration memory is cleared
and requires loading.
Related Configuration register bits:
• Configuration Register 1 (Register 11-2),
DATOUT <8:7>:
- bit 8 bit 7
11.31 LFDATA Output Selection
0
0
1
0
0: Demodulator Output
1: Carrier Clock Output
0: RSSI Output
The LFDATA output can be configured to pass the
Demodulator output, Received Signal Strength Indicator
(RSSI) output, or Carrier Clock. See Configuration
Register 1 (Register 11-2) for more details.
1: RSSI Output
• Configuration Register 0 (Register 11-1): all bits
11.31.1 DEMODULATOR OUTPUT
The demodulator output is the default configuration of
the output selection. This is the output of an envelope
detection circuit. See Figure 11-9 for the demodulator
output.
© 2007 Microchip Technology Inc.
DS41232D-page 111
MICROCHIP [ MICROCHIP ]
