— 5 —
Pin No.
Terminal
In/ Out
Function
1, 2
TEST1, TEST2
Not used. Connected to ground.
Power ON reset terminal. When the power switch is
3
RESET
In
turned on, the terminal receives a low level signal and
the internal circuits of the LSI are initialized.
4
AVDD
In
+5 V sorce for the built-in DAC
5
OUT
Out
Sound waveform output
6
AGND
In
Ground (0 V) source for the built-in DAC
7
GND
In
Ground (0 V) source
8
COSI
In
21.725 MHz clock pulse input
9
COSO
Not used.
10
VDD
In
+5 V source
11 ~ 18
KI0 ~ KI7
In
Input terminals from keys and switches
19, 20
KO11, KO10
Not used.
21 ~ 30
KO9 ~ KO0
Out
Key and switch scan signal outputs
CPU (LSI201: MSM6387-13)
The CPU contains a sound data ROM and a DAC (Digital to Analog Convertor), and it provides a sound
waveform in accordance with the pressed key and the selected tone.
The following table shows the pin functions of LSI201.
FILTER BLOCK
Since the sound signal from the CPU is a stepped waveform, the filter block is added to smooth the
waveform.
AVDD
C203
Q201
2SC1740SQ
R202
C202
AG
AG
R204
R203
C201
To main volume
From CPU
