HD404669 Datasheet, PDF (93/142 Pages) Hitachi Semiconductor – Low-Voltage AS Microcomputers with On-Chip DTMF Generation Circuit

HD404669 Series
1
2
3
A
R1 (697Hz)
4
5
6
B
R2 (770Hz)
7
8
9
C
R3 (852Hz)
0
#
D
R4 (941Hz)
Figure 70 DTMF Keypad and Frequencies
Tone Generator Mode Register (TGM: $019): The tone generator mode register (TGM: $019) is a 4-bit
write-only register that controls the generated DTMF frequencies as shown in figure 71. TGM is initialized
to $0 by an MCU reset or in stop mode, watch mode, and subactive mode.
Tone generator mode register (TGM: $019)
Bit
Initial value
Read/Write
Bit name
3
0
W
TGM3
2
0
W
TGM2
1
0
W
TGM1
0
0
W
TGM0
TGM3
0
0
1
1
TGM2
0
1
0
1
TONEC output frequencies
C1 (1,209 Hz)
C2 (1,336 Hz)
C3 (1,477 Hz)
C4 (1,633 Hz)
TGM1
0
0
1
1
TGM0
0
1
0
1
TONER output frequencies
R1 (697 Hz)
R2 (770 Hz)
R3 (852 Hz)
R4 (941 Hz)
Figure 71 Tone Generator Mode Register (TGM)
93