w925e625 ETC-unknow, w925e625 Datasheet - Page 59

• Manufacturer Part Number: w925e625
• Description: 8-bit Cid Microcontroller
• Manufacturer: ETC-unknow

The FSK demodulation function can demodulate Bell 202 and ITU-T V.23 Frequency Shift keying
(FSK) with 1200 baud rate. When the decoder receives the FSK serial data, the serial data will be
demodulated into bit FDATA with 1200 baud rate in the mean time the synchronous clock signal is
output to the bit FCLK. As the decoder receives one byte, the internal serial-to-parallel circuit sets the
bit FDR and converts the 8-bit serial data into the byte register FSKDR. The rising edge of bit FDR will
set the flag FDRF to produce CID interrupt but FDRF is cleared by software. User can get the FSK
data by reading register FSKDR or sampling the bit FDATA. The timing of FSK demodulation is shown
in Figure 6-24.
Tip/Ring
FSKDR
FCLK
FDRF
FDATA
FDR
* Mark bit or redundant stop bit(s), will be omitted.
+ Clear by software.
Tip/Ring
FSKE
FCD
1*
Figure 6-23 FSK Detection Enable and FSK Carrier Present and Absent Timing
1
start
0
t
FSKE
start
Note
b0 b1 b2
Figure 6-24 Serial Data Interface Timing of FSK Demodulation
t
IDD
t
b0 b1 b2 b3 b4 b5 b6 b7
CP
Analog FSK Signal
1st byte data
b3 b4 b5 b6 b7 1*
1st byte data
t
CA
- 59 -
1/f
stop
DCLK0
1
t
CRD
start
stop
0
t
RH
start
b0 b1 b2 b3 b4 b5 b6 b7 1
b0 b1 b2 b3 b4 b5 b6 b7
1st byte data
t
Analog FSK Signal
2nd byte data
CP
Publication Release Date: July 4, 2005
2nd byte data
+
W925E/C625
stop
t
start
CA
0
stop
2nd byte data
start
b0
Revision A10