Casio CTK-330 Service Manual page 5

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
1 ~ 29 MA14 ~ NC2
30 DGND
31 DVCC
32, 33 XTLO, XTLI
34 NC3
35 RSTB
36 P24/RXD
37 P25/TXD
38 NMI
39 APO
40 NC4
41 REFH
42, 43 NC5, NC6
44 DAOR
45 NC7
46 AVdac
47 DAOL
48 REFL
49 AGdac
50 AGadc
51 ANI
52 AVadc
53 NC8
54 MOD0
55, 56 MOD1, MOD2
57 KO9/P40
58 ~ 65 KI0/P30 ~ KI7/P37
66 ~ 73 KO1/P50 ~ KO8/P57
74 ~ 77 P20 ~ P23
78 NC9
79 LVCC
80 ~ 82 CC1 ~ CC3
83 ~ 87
88 ~ 95 La ~ Lg, Lp
96 LGND
97 ~ 100
FILTER BLOCK
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.
Amp.
LA4598
I n / O u t
—
In
In
In/Out
—
In
—
—
In
Out
—
Out
—
Out
—
In
Out
Out
In
In
—
In
—
In
In
In
In
Out
Out
—
In
Out
— —
Out
In
— —
Function
Not used.
Ground (0 V) source
+5 V source
20 MHz clock input/output
Not used. Connected to ground.
Reset signal input
Not used. Connected to +5 V.
Not used.
Power on signal input. Connected to +5 V.
APO (Auto Power Off) signal output
Not used.
Terminal for the built-in DAC
Not used.
Right channel sound waveform output
Not used.
+5 V source for the built-in DAC and ADC
Left channel sound waveform output
Terminal for the built-in DAC and ADC
Ground source for the built-in DAC
Ground source for the built-in ADC
Not used. Connected to ground.
+5 V source for the internal ADC
Not used. Connected to +5 V.
Mode selection terminal
Mode selection terminal
APO cancelation signal input
Terminals for key/button input signal
Terminals for key scan signal
Terminals for button scan signal
Not used.
+5 V source
LED common signal output
Not used.
LED segment signal output
Ground (0 V) source
Not used.
Filter
Block
— 3 —
CPU
MSM6755B-08