W925EP01 Datasheet, PDF (64/108 Pages) Winbond – 8-BIT CID MICROCONTROLLER

W925EP01/ W925EP01FG
FSK TRANSMIT DATA BUFFER
(initial=00H)
Bit:
7
-
6
5
4
3
2
1
0
-
-
-
-
-
- FSKTB.0
Mnemonic: FSKTB
Address: C7h
FSKTB.0: Only this bit will be latched and send out as FSK signal
When FTE enable will set the FDS to high to enable the internal latch clock in 1200Hz. When FDS is
in high state, FSKTB bit0 will be sent out by FSK modulator at the rising edge of latch clock. FDS
could be cleared by software to inform no more data will be sent out after the last bit is sent
completely. If the FDS is cleared then FTE will become low at next rising latch clock to disable FSK
modulator and clear FDS by hardware automatically.
When FTE is set, FSK modulation flag (FSF) will be set at every rising edge of latch clock to produce
an interrupt shared with CID interrupt routine. If a CID interrupt occurs, user can check FSF to know if
this interrupt is caused by FSK modulator. The only way to stop FSK signal immediately is to disable
FTE by software.
6.13 CAS Generator
W925EP01 provides a CAS generator, which outputs the CAS signal to the DTMF pin. The CAS
generator can work well at the operating frequency of 4M/8MHz. A CAS generator register CASGE
controls the CAS output and specifies the desired low/high frequency. The tones are divided into two
groups (low group and high group). When the CASGE is cleared, the DTMF pin is in tri-state. The
relation between the CAS signal and the corresponding is shown in following.
Bit:
7
6
5
4
3
2
1
0
CASGE DTGE HE
LE
L1
L0
H1
H0
Mnemonic: DTMFG
Address: BAh
CASGE: Enable CAS tone output to DTMF pin.
HE: Enable CAS/DTMF high group frequency output.
LE: Enable CAS/DTMF low group frequency output.
HE
LE
0
0
0
1
1
0
1
1
CAS SELECTED TONE
Low
2130Hz
2750Hz
2130Hz & 2750Hz
To change the signal strength of CAS, user can modify the SFR bit0 and bit1 in FSKTC.
LO0, LO1: CAS transmitting level option. It just is suitable for 2130Hz. The output levels of 2750Hz will
higher 2dBm than it.
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