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CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (FSK Demodulator)
4.15 FSK Demodulator
4.15.1 Configuration of FSK demodulator
The S1C63558 has a built-in FSK (Frequency Shift Keying) demodulator that interfaces to various calling
information delivery services such as calling number delivery (compatible with ITU-T V.23/Bell 202).
Figures 4.15.1.1 and 4.15.1.2 show the block diagram of the FSK demodulator and the configuration of
FSK core block, respectively.
Ring detection
interrupt
Carrier detection
interrupt
FSK core
AV
DD
AV
SS
TIP
RING
FB
BPOUT
CDIN
RDIN
RDRC
V
REF
P3x port
136
EIRDET
Interrupt mask register
IRDET
Interrupt factor flag
ICDET
Interrupt factor flag
EIRDET
Interrupt mask register
FOSC3
RDET
CDET
PWDN
FSKIN
SIN (P30)
SIF (2) enable
Fig. 4.15.1.1 FSK demodulator block diagram
FOSC3
RDET
CDET
FSKON
MUX
A
OUT
B
A/B
EPSON
RDETCP
RDET comparison register
CDETCP
CDET comparison register
OSC3 oscillation circuit
RDET
Ring detection bit
CDET
Carrier detection bit
FSKON
FSK control register
TRXD7S–TRXD0S
Transmit/receive data register
Serial interface (2)
ESIFS
SIF (2) enable register
S1C63558 TECHNICAL MANUAL
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