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 (0 V) source
31DVCCIn+5 Vsource
32, 33XTLO, XTLIIn/Out2MHz clock input/output0
34NC3NNot used. Connected to ground.
35RSTBInReset signal input
36P24/RXDNNot used. Connected to +5 V.
37P25/TXDNNot used.
38NMIInPower on signal input. Connected to +5 V.
39APOOutAPO (Auto Power Off) signal output
40NC4NNot used.
41REFHOutTerminal for the built-in DAC
42, 43NC5, NC6NNot used.
44DAOROutRight channel sound waveform output
45NC7NNot used.
46AVdacIn+5 Vsource for the built-in DAC and ADC
47DAOLOutLeft channel sound waveform output
48REFLOutTerminal for the built-in DAC and ADC
49AGdacIn Ground source for the built-in DAC
50AGadcInGround source for the built-in ADC
51ANINNot used. Connected to ground.
52AVadcIn+5 Vsource for the internal ADC
53NC8NNot used. Connected to +5 V.
54MOD0InMode selection terminal
55, 56MOD1, MOD2InMode selection terminal
57KO9/P40InAPO cancelation 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 scan signal
78NC9NNot used.
79LVCCIn+5 V source
80 ~ 82CC1 ~ CC3Out LED common signal output
83 ~ 87NNNot used.
88 ~ 95La ~ Lg, LpOutLED segment signal output
96LGNDInGround (0 V) 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.
Amp.
Filter
CPU
LA4598BlockMSM6755B-08
N 3 N |
ACEC
