W925EP01 Datasheet, PDF (62/108 Pages) Winbond – 8-BIT CID MICROCONTROLLER

W925EP01/ W925EP01FG
6.11 DTMF Generator
W925EP01 provides a DTMF generator, which outputs the dual tone multi-frequency signal to the
DTMF pin. The DTMF generator can work well at the operating frequency of 4M/8MHz. A DTMF
generator register DTMFG controls the DTMF output and specifies the desired low/high frequency.
The tones are divided into two groups (low group and high group). When the generator is disabled,
the DTMF pin is in tri-state. The relation between the DTMF signal and the corresponding touch-tone
keypad is shown in Figure 6-9.
C1
R1 ₁
R2 ₄
R3 ₇
R4 _*
C2 C3 C4
23 A
ROW/COL
R1
R2
R3
56 B
R4
89 C
C1
C2
0# D
C3
C4
Figure 6-9 The Relation Between DTMF and Keypad
FREQUENCY
697 Hz
770 Hz
852 Hz
941 Hz
1209 Hz
1336 Hz
1477 Hz
1633 Hz
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.
DTGE: Enable dual tone output to DTMF pin.
HE: Enable CAS/DTMF high group frequency output.
LE: Enable CAS/DTMF low group frequency output.
L1
L0
H1
H0
x
x
0
0
x
x
0
1
x
x
1
0
x
x
1
1
0
0
x
x
0
1
x
x
1
0
x
x
1
1
x
x
DTMF SELECTED TONE
1209Hz
1336Hz
1477Hz
1633Hz
697Hz
770Hz
852Hz
941Hz
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