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136 EPSON S1C63558 TECHNICAL MANUAL
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.
RDETCP
RDET comparison register
EIRDET
Interrupt mask register
Data bus
CDETCP
CDET comparison register
EIRDET
Interrupt mask register
IRDET
Interrupt factor flag
ICDET
Interrupt factor flag
RDET
Ring detection bit
CDET
Carrier detection bit
FSKON
FSK control register
TRXD7S–TRXD0S
Transmit/receive data register
ESIFS
SIF (2) enable register
OSC3 oscillation circuit
FSK core
P3x port
A
B
A/B
MUX
SIN (P30)
SIF (2) enable
FOSC3
RDET
CDET
FSKON
OUT
FOSC3
RDET
CDET
PWDN
FSKIN
Ring detection
interrupt
Carrier detection
interrupt
Serial interface (2)
AVDD
AVSS
TIP
RING
FB
BPOUT
CDIN
RDIN
RDRC
VREF
Fig. 4.15.1.1 FSK demodulator block diagram