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.TerminalIn/OutFunction
1 ~ 29MA14 ~ NC2NNot used.
30DGNDInGround (0V) source
31DVCCIn+5V source
32, 33XTLO, XTLIIn/Out20MHz clock input/output
34NC3NNot used. Connected to ground.
35RSTBInReset signal input
36P24/RXDNNot used. Connected to +5V.
37P25/TXDNNot used.
38NMIInPower on signal input
39APOOutAPO (Auto Power Off) signal output
40NC4NNot used.
41REFHOutTerminal for the internal DAC
42, 43NC5, NC6NNot used.
44DAOROutRight channel sound waveform output
45NC7NNot used.
46AVdacIn+5V source for the internal DAC and ADC
47DAOLOutLeft channel sound waveform output
48REFLOutTerminal for the interand ADCnal DAC
49AGdacIn Ground source for the internal DAC
50AGadcInGround source for the internal ADC
51ANINNot used. Connected to ground.
52AVadcIn+5V source for the internal ADC
53NC8NNot used. Connected to +5V.
54MOD0InMode selection terminal
55, 56MOD1, MOD2InMode selection terminal
57KO9/P40InPower source detection signal input
58 ~ 65KI0/P30 ~ KI7/P37InTerminals for key/button input signal
66 ~ 73KO1/P50 ~ KO8/P57Out Terminals for key scan signal
74 ~ 77P20 ~ P23OutTerminals for button input signal
78NC9NNot used.
79LVCCIn+5V source
80 ~ 82CC1 ~ CC3Out LED common signal output
83 ~ 87NNNot used.
88 ~ 95La ~ Lg, LpOutNot used.
96LGNDInGround (0V) source
97 ~ 100NNNot used.
FILTER BLOCK
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the waveform.
10
AVDD
+
10 V 22 ?
AG
2SC1740SQ
10 K10 K10 K
16 V 10 ?
C332(H)From the CPU
+
To main volume
2.2 K
33 K
C152 (H)
C221B (A)
AGAGAGAG
N 5 N |
ACEC
PANASONIC
