CS9236-CQ データシートの表示（PDF） - Cirrus Logic

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CS9236-CQ

Single-Chip Wavetable Music Synthesizer

Cirrus Logic 

CS9236

GENERAL MIDI (GM) MELODIC

INSTRUMENTS AND PERCUSSION

SOUNDS

The CS9236 supports 128 melodic instruments and 47 per-

cussive sounds as specified by the General MIDI Level 1

specification.

MIDI messages generally consist of a single status byte fol-

lowed by one or two data bytes (Real-Time messages and

System Exclusive messages are exceptions). The status byte

is an eight-bit value which indicates the type of message, and

for Channel Voice or Channel Mode messages, the MIDI

channel number to which the message applies. The most sig-

nificant bit of the Status byte is always a “1”. The most sig-

nificant bit a MIDI Data byte is always a “0”, so a data byte

contains only 7 bits of useful data. Status bytes and Data

bytes for functions not implemented are ignored.

In General MIDI (GM) instruments like the CS9236, MIDI

channels 1 - 9 and 11 - 16 are used for melodic instruments.

On MIDI channels 1 - 9 and 11 - 16, the MIDI Program

Change message is used to select the instrument to be used on

a specific MIDI channel. The General MIDI melodic instru-

ment set is listed in Table 1.

The General MIDI system reserves channel 10 for key-

mapped percussion sounds. The General MIDI percussion

map defines the association of percussion sounds to key num-

bers (note numbers) for use on channel 10. Program Change

messages on channel 10 are ignored. The CS9236 includes

default settings for the PAN, the REVERB SEND level, and

the CHORUS SEND level for each of the General MIDI per-

cussion sounds. The PAN setting used for a percussion sound

on channel 10 is a function of both the CS9236 default value

and the MIDI PAN value for channel 10 (PAN messages on

channel 10 are interpreted by the CS9236 as relative, rather

than absolute, values). For example, the default pan value for

the Hand Clap is 54 (10 units left of center) and the default

pan value for the Tambourine is 74 (10 units right of center).

A MIDI PAN message on channel 10 indicating a new pan

value of 50 (14 units left of center) for the channel would

place the Hand Clap at 40 (24 units left of center), and the

Tambourine at 60 (4 units left of center). A MIDI PAN mes-

sage on channel 10 indicating a new pan value of 0 (64 units

left of center, or “hard left”) for the channel would place the

Hand Clap at 0 (hard left), and the Tambourine at 10 (54 units

left of center). The REVERB SEND level used for a percus-

sion sound on channel 10 will be either the default value for

that percussion sound, or the MIDI REVERB SEND value

(MIDI Controller 91), whichever is greater. The CHORUS

SEND level used for a percussion sound on channel 10 will

be either the default value for that percussion sound, or the

MIDI CHORUS SEND value (MIDI Controller 93), which-

ever is greater.

Some of the percussion instrument sounds available on chan-

nel 10 belong to “mutually exclusive groups”. Although mul-

tiple sounds may be generated simultaneously on channel 10

when operating in the normal POLY ON mode, no more than

one sound from each of the mutually exclusive groups may

sound at a given time. For example, the Open Hi-Hat (Note

# 46), the Closed Hi-Hat (Note # 42), and the Pedal Hi-Hat

(Note # 44) all belong to the same mutually exclusive group.

If the Open Hi-Hat was already sounding when a MIDI

NOTE ON message was received for the Closed Hi-Hat, the

Closed Hi-Hat would be played while the Open Hi-Hat would

be immediately forced into it’s release phase (the two notes

would overlap only for the duration of the release phase of the

Open Hi-Hat sound). A Crash Cymbal sound (not a member

of this mutually exclusive group) which was also playing

when the NOTE ON message was received would not be af-

fected.

The General MIDI percussion sound map is given in Table 2.

This table also indicates the mutually exclusive group mem-

bership for each of the percussion sounds as implemented in

the CS9236.

10

DS214PP11

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