W742S81A Datasheet, PDF (31/47 Pages) Winbond – 4 BIT MICROCONTROLLER

W742S81A
Figure 6-13 The relation between the touch tone keypad and the frequency
6.20.1 DTMF register
DTMF register is organized as 4-bit binary register. By controlling the DTMF register, one tone of the
low/high group can be selected. The MOV DTMF,R instruction can specify the wanted tones. The bit
descriptions are as follows:
Note: W means write only.
3
2
1
0
DTMF W
W
W
W
b3
b2
b1
b0
X
X
0
0
High
X
X
0
1
group
X
X
1
0
X
X
1
1
0
0
X
X
Low
0
1
X
X
group
1
0
X
X
1
1
X
X
Selected tone
1209 Hz
1336 Hz
1477 Hz
1633 Hz
697 Hz
770 Hz
852 Hz
941 Hz
Note: X means this bit do not care.
6.20.2 Dual Tone Control Register (DTCR)
Dual tone control register is organized as 4-bit binary register. The output of the dual or single tone will be
controlled by this register. The MOV DTCR,#I instruction can specify the wanted status. The bit
descriptions are as follows:
3
2
1
0
DTCR
W
W
W
Note: W means write only.
Bit 0 = 1 Low group tone output is enabled.
Bit 1 = 1 High group tone output is enabled.
Bit 2 = 1 DTMF output is enabled. When Bit 2 is reset to 0, the DTMF output pin will be Hi-Z state.
Bit 3 is reserved.
Publication Release Date: March 2003
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Revision A1