Bedienungsanleitung Roland BK-9 - Midi Implementation (Seite 24 von 26) (Englisch)

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MIDI Implementation

From the preceding table, since 0AH = 10, 03H = 3, 09H = 9, 0DH = 13

((10 x 16 + 3) x 16 + 9) x 16 + 13 = 41885

What is the nibbled expression of the decimal value 1258?

16) 1258

16) 78... 10

16) 4... 14

0... 4

Since from the preceding table, 0 = 00H, 4 = 04H, 14 = 0EH, 10 = 0AH, the

answer is 00 04 0E 0AH.

z Examples of Actual MIDI Messages

<Example1> 92 3E 5F

9n is the Note-on status, and n is the MIDI channel number. Since 2H = 2,

3EH = 62, and 5FH = 95, this is a Note-on message with MIDI CH = 3, note

number 62 (note name is D4), and velocity 95.

<Example2> CE 49

CnH is the Program Change status, and n is the MIDI channel number.

Since EH = 14 and 49H = 73, this is a Program Change message with MIDI

CH = 15, program number 74 (Flute in GS).

<Example3> EA 00 28

EnH is the Pitch Bend Change status, and n is the MIDI channel number.

The 2nd byte (00H = 0) is the LSB and the 3rd byte (28H = 40) is the MSB,

but Pitch Bend Value is a signed number in which 40 00H (= 64 x 128 + 0 =

8192) is 0, so this Pitch Bend Value is 28 00H - 40 00H = 40 x 128 + 0 - (64 x

128 + 0) = 5120 - 8192 = -3072

If the Pitch Bend Sensitivity is set to 2 semitones, -8192 (00 00H) will cause

the pitch to change 200 cents, so in this case -200 x (-3072) / (-8192) = -75

cents of Pitch Bend is being applied to MIDI channel 11.

<Example4> B3 64 00 65 00 06 0C 26 00 64 7F 65 7F

BnH is the Control Change status, and n is the MIDI channel number. For

Control Changes, the 2nd byte is the control number, and the 3rd byte is

the value. In a case in which two or more messages consecutive messages

have the same status, MIDI has a provision called “running status” which al-

lows the status byte of the second and following messages to be omitted.

Thus, the above messages have the following meaning.

B3 64 00 MIDI ch.4, lower byte of RPN parameter number: 00H

(B3) 65 00 (MIDI ch.4) upper byte of RPN parameter number: 00H

(B3) 06 0C (MIDI ch.4) upper byte of parameter value: 0CH

(B3) 26 00 (MIDI ch.4) lower byte of parameter value: 00H

(B3) 64 7F (MIDI ch.4) lower byte of RPN parameter number: 7FH

(B3) 65 7F (MIDI ch.4) upper byte of RPN parameter number: 7FH

In other words, the above messages specify a value of 0C 00H for RPN

parameter number 00 00H on MIDI channel 4, and then set the RPN

parameter number to 7F 7FH.

RPN parameter number 00 00H is Pitch Bend Sensitivity, and the MSB

of the value indicates semitone units, so a value of 0CH = 12 sets the

maximum pitch bend range to ±12 semitones (1 octave). (On GS sound

ources the LSB of Pitch Bend Sensitivity is ignored, but the LSB should be

transmitted anyway (with a value of 0) so that operation will be correct on

any device.)

Once the parameter number has been specied for RPN or NRPN, all Data

Entry messages transmitted on that same channel will be valid, so after the

desired value has been transmitted, it is a good idea to set the parameter

number to 7F 7FH to prevent accidents. This is the reason for the (B3) 64 7F

(B3) 65 7F at the end.

It is not desirable for performance data (such as Standard MIDI File data) to

contain many events with running status as given in <Example 4>.

This is because if playback is halted during the song and then rewound

or fast-forwarded, the sequencer may not be able to transmit the correct

status, and the sound source will then misinterpret the data. Take care to

give each event its own status.

It is also necessary that the RPN or NRPN parameter number setting and

the value setting be done in the proper order. On some sequencers, events

occurring in the same (or consecutive) clock may be transmitted in an

order dierent than the order in which they were received. For this reason

it is a good idea to slightly skew the time of each event (about 1 tick for

TPQN = 96, and about 5 ticks for TPQN = 480).

• TPQN: Ticks Per Quarter Note

z Example of an Exclusive Message and Calculating a

Checksum

Roland Exclusive messages are transmitted with a checksum at the end

(before F7) to make sure that the message was correctly received. The

value of the checksum is determined by the address and data (or size) of

the transmitted exclusive message.

{ How to Calculate the Checksum (Hexadecimal

Numbers are Indicated by ‘H’)

The checksum is a value derived by adding the address, size and checksum

itself and inverting the lower 7 bits.

Here’s an example of how the checksum is calculated. We will assume that

in the exclusive message we are transmitting, the address is aa bb ccH and

the data or size is dd ee H.

aa + bb + cc + dd + ee +  = sum

sum / 128 = quotient ... remainder

128 - remainder = checksum

(However, the checksum will be 0 if the remainder is 0.)

<Example> Setting REVERB MACRO to ROOM 3

According to the “Parameter Address Map,” the REVERB MACRO Address is

40 01 30H, and ROOM

3 is a value of 02H. Thus,

F0 41 10 42 12 40 01 30 02 ?? F7

(1) (2) (3) (4) (5) Address data Checksum (6)

(1) Exclusive Status, (2) ID (Roland), (3) Device ID (17),

(4) Model ID (GS), (5) Command ID (DT1), (6) End of Exclusive

Next we calculate the checksum.

40H + 01H + 30H + 02H = 64 + 1 + 48 + 2 = 115 (sum)

115 (sum) / 128 = 0 (quotient) ... 115 (remainder)

checksum = 128 - 115 (remainder) = 13 = 0DH

This means that F0 41 10 42 12 40 01 30 02 0D F7 is the message we

transmit.

z About Tuning

In MIDI, individual Parts are tuned by sending RPN #1 (Master Fine Tuning)

to the appropriate MIDI channel.

In MIDI, an entire device is tuned by either sending RPN #1 to all MIDI

channels being used, or by sending a System Exclusive MASTER TUNE

(address 40 00 00H).

RPN #1 allows tuning to be specied in steps of approximately 0.012 cents

(to be precise, 100/8192 cent), and System Exclusive MASTER TUNE allows

tuning in steps of 0.1 cent. One cent is 1/100th of a semitone.

The values of RPN #1 (Master Fine Tuning) and System Exclusive MASTER

TUNE are added together to determine the actual pitch sounded by each

Part.

Roland BK-9 - Midi Implementation Seite 24

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