Pin Function of Percussion Generator

Pin No.

Signal

In/Out

Function

1

RESET

In

Reset signal input. LOW active.

The terminal holds LOW level at power switch on for initializing the internal circuit

2

CLK

In

Clock pulse (256 kHz) input

3

No function

4

wr

In

Write signal input. LOW active.

The LSI reads the percussion data from the CPU when the terminal is LOW level.

5

CS

In

Chip select signal input. Fixed at LOW level.

6-13

DO ~ D7

In

Data bus (DO ~ D7)

14

DVSS

Ground (0V) source for internal digital circuit

15, 16

No function

17

AVSS

Ground (0V) source for internal DAC

18

MIX-0

Out

Analog percussion signal output

19

AVDD

+5V source for internal DAC

20-27

No function

: DVDD

+5V source for internal digital circuit

8. MELODY CIRCUIT

K014

Casio Trigger

Pitch

Envelope -Wt-

Pitch SE

Pitch SF

CA91A02

Filter

CA91A02

Pitch

Envelope -Wt-

SG EG

Pitch SE

Pitch SF

Envelope EF

\ Melody or J Obbligato

Melody or Bass

Melody or ' Chord

Envelope EF

Melody or ' Chord

Filter

CPU outputs four each of pitch and envelope signals.

Normally all the signals are for melody sounds however, when the demonstration music is played, each pitch and envelope signals become obbligato, bass, chord, or melody sounds. CA91A02 contains four mixing amplifiers and merges each pitch and envelope signals. Gain Controller balances the sound volume of melody and accompaniments for demonstration music. Signal K014 normally stays HIGH level so that all the switches turn on. When the demonstration music is played, K014 falls to LOW level turning the switches off and all the accompaniment signals are reduced as they pass through the resistors.

9. SAMPLING CIRCUIT

Fig. 1 Sample Sound Input Circuit

Start

Fig. 2 Vin Input Trigger Level

Start

Fig. 2 Vin Input Trigger Level

As shown in Fig. 1. the circuit provides sampling signals to the Vin terminal of the CPU. Resistors 10OKohm and (100 + 4.7) Kohm bias the sampling signal on 2.863V.

When the sampling sound level exceeds ± 0.315V as shown in Fig. 2, the CPU starts to transmit the sampling sound data to the RAMs during the following period.

While sampling, the CPU transmits the sampling sound data to the sampling RAMs directly. While sampling, CPU does not output key common signals (KOO ~ K09) so that the keyboard becomes inoperative.

Sampled sounds are digitized in CPU and transmitted to the RAM.

10. PERIPHERAL DEVICE ACCESS

CPU MSM6283-05GS

D0-D7 POO

CPU MSM6283-05GS

D0-D7 POO

Data bus IOO ~ I07:

PG 256kHz

0E

O

<

CO

AO

2

CM

;

O

O

A14

DC

CO CM

00

Q Q_

i

a.

07

RESET WR

D7 CS

AiPD43256C-12L is a 256Kbit RAM for storing sampling sounds and Demo Music ROM data. The data in RAM are kept even power switch OFF as long as DC7.5V is provided.

iuPD23C256EAC is a 256Kbit ROM and contains preset tone, percussion data, and system execution program.

MSM6294-02 is a percussion generator and issues percussion sounds in accordance with the data from The chip select condition is as follows.

Ship selection

A15

CE

CE1

RAM

L

L

X

ROM

H

L

X

Percussion generator

X

X

L

H: High level L : Low level X: Irrelevant

11. DEMO. MUSIC ROM ACCESS

Demo Music ROM

CE1 01 02 CP D1-D4

CE2

C1

C2

OP

CPU

t

MSM6283-05GS

I07

AO

A14

A15

CE

K013

Assigning Demo Music ROM by being LOW of signal CE2, CPU reads data from the ROM directly and generates programmed melody and accompaniment signals.

Since the data bus D4 ~ D7 carries data and address, signal OP determines either the bus carries data or address.

Signal C1 and C2 are clock pulse for data transfer.

OP

D4 ~ D7

HIGH

Data

LOW

Was this article helpful?

0 0

Post a comment