— 5 —
+
+
AVDD
AG
AG
AG
AG
AG
16 V 10 µ
2SC1740SQ
10 K
10
10 K
10 K
C332(H)
33 K
C152 (H)
C221B (A)
10 V 22 µ
2.2 K
To main volume
From the CPU
CPU (LSI101: MSM6755B-06)
The CPU contains a sound data ROM and a DAC (Digital to Analog Convertor), and it provides left and right
channel sound waveforms in accordance with the pressed key and the selected tone.
The following table shows the pin functions of LSI101.
Pin No.
Terminal
I n / O u t
Function
1 ~ 29
MA14 ~ NC2
—
Not used.
30
DGND
In
Ground (0V) source
31
DVCC
In
+5V source
32, 33
XTLO, XTLI
In/Out
20MHz clock input/output
34
NC3
—
Not used. Connected to ground.
35
RSTB
In
Reset signal input
36
P24/RXD
—
Not used. Connected to +5V.
37
P25/TXD
—
Not used.
38
NMI
In
Power on signal input
39
APO
Out
APO (Auto Power Off) signal output
40
NC4
—
Not used.
41
REFH
Out
Terminal for the internal DAC
42, 43
NC5, NC6
—
Not used.
44
DAOR
Out
Right channel sound waveform output
45
NC7
—
Not used.
46
AVdac
In
+5V source for the internal DAC and ADC
47
DAOL
Out
Left channel sound waveform output
48
REFL
Out
Terminal for the internal DAC and ADC
49
AGdac
In
Ground source for the internal DAC
50
AGadc
In
Ground source for the internal ADC
51
ANI
—
Not used. Connected to ground.
52
AVadc
In
+5V source for the internal ADC
53
NC8
—
Not used. Connected to +5V.
54
MOD0
In
Mode selection terminal
55, 56
MOD1, MOD2
In
Mode selection terminal
57
KO9/P40
In
Power source detection signal input
58 ~ 65
KI0/P30 ~ KI7/P37
In
Terminals for key/button input signal
66 ~ 73
KO1/P50 ~ KO8/P57
Out
Terminals for key scan signal
74 ~ 77
P20 ~ P23
Out
Terminals for button input signal
78
NC9
—
Not used.
79
LVCC
In
+5V source
80 ~ 82
CC1 ~ CC3
Out
LED common signal output
83 ~ 87
—
—
Not used.
88 ~ 95
La ~ Lg, Lp
Out
Not used.
96
LGND
In
Ground (0V) source
97 ~ 100
—
—
Not used.
FILTER BLOCK
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.
