Bedienungsanleitung Roland Juno-G (Seite 239 von 252) (Holländisch)

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MIDI Implementatie

■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.

<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 12+80 = 8192) is 0, so this Pitch Bend Value is

28 00H - 40 00H = 40 x 12+80 - (64 x 12+80) = 5120 - 8192 = -3072

If the Pitch Bend Sensitivity is set to 2 semitones, -8192 (00 00H) will cause the toonhoogte 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 allows 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 generators 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 specified 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 generator 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 different 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

■Example of an Exclusive Message and

Calculating a Checksum

Roland Exclusive messages (RQ1, DT1) 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 aabbccddH and the data or size is eeffH.

aa + bb + cc + dd + ee + ff = sum

sum ÷ 128 = quotient ... remainder

128 - remainder = checksum

<Example> Setting CHORUS TYPE of PERFORMANCE COMMON to

DELAY (DT1)

According to the Parameter Address Map (p. 222), the start address of Temporary

Performance is 10 00 00 00H, the offset address of CHORUS at PERFORMANCE COMMON

is 04 00H, and the address of CHORUS TYPE is 00 00H. Therefore the address of CHORUS

TYPE of PERFORMANCE COMMON is;

10 00 00 00H

04 00H

+) 00 00H

10 00 04 00H

DELAY has the value of 02H.

So the system exclusive message should be sent is;

F0 41 10 00 00 15 12 10 00 04 00 02 ?? F7

(1) (2) (3) (4) (5) address data checksum (6)

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

(4) Model ID (JUNO-G) (5) Command ID (DT1) (6) End of Exclusive

Then calculate the checksum.

10H + 00H + 04H + 00H + 02H = 16 + 0 + 4 + 0 + 2 = 22 (sum)

22 (sum) ÷ 128 = 0 (quotient) ... 22 (remainder)

checksum = 128 - 22 (remainder) = 106 = 6AH

This means that F0 41 10 00 00 15 12 10 00 04 00 02 6A F7 is the message should be sent.

Roland Juno-G Seite 239

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