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94
MIDI Implementation
4. Appendices
■
Decimal and hexadecimal conversion table
(The letter “H” follows numbers in hexadecimal notation.)
MIDI uses hexadecimal notation in 7-bit units to indicate data values and addresses and
sizes within an exclusive message. Hexadecimal and decimal numbers correspond as
follows.
+——————+——————++——————+——————++——————+——————++——————+——————+
| Deci | Hexa || Deci | Hexa || Deci | Hexa || Deci | Hexa |
+——————+——————++——————+——————++——————+——————++——————+——————+
| 0 | 00H || 32 | 20H || 64 | 40H || 96 | 60H |
| 1 | 01H || 33 | 21H || 65 | 41H || 97 | 61H |
| 2 | 02H || 34 | 22H || 66 | 42H || 98 | 62H |
| 3 | 03H || 35 | 23H || 67 | 43H || 99 | 63H |
| 4 | 04H || 36 | 24H || 68 | 44H || 100 | 64H |
| 5 | 05H || 37 | 25H || 69 | 45H || 101 | 65H |
| 6 | 06H || 38 | 26H || 70 | 46H || 102 | 66H |
| 7 | 07H || 39 | 27H || 71 | 47H || 103 | 67H |
| 8 | 08H || 40 | 28H || 72 | 48H || 104 | 68H |
| 9 | 09H || 41 | 29H || 73 | 49H || 105 | 69H |
| 10 | 0AH || 42 | 2AH || 74 | 4AH || 106 | 6AH |
| 11 | 0BH || 43 | 2BH || 75 | 4BH || 107 | 6BH |
| 12 | 0CH || 44 | 2CH || 76 | 4CH || 108 | 6CH |
| 13 | 0DH || 45 | 2DH || 77 | 4DH || 109 | 6DH |
| 14 | 0EH || 46 | 2EH || 78 | 4EH || 110 | 6EH |
| 15 | 0FH || 47 | 2FH || 79 | 4FH || 111 | 6FH |
| 16 | 10H || 48 | 30H || 80 | 50H || 112 | 70H |
| 17 | 11H || 49 | 31H || 81 | 51H || 113 | 71H |
| 18 | 12H || 50 | 32H || 82 | 52H || 114 | 72H |
| 19 | 13H || 51 | 33H || 83 | 53H || 115 | 73H |
| 20 | 14H || 52 | 34H || 84 | 54H || 116 | 74H |
| 21 | 15H || 53 | 35H || 85 | 55H || 117 | 75H |
| 22 | 16H || 54 | 36H || 86 | 56H || 118 | 76H |
| 23 | 17H || 55 | 37H || 87 | 57H || 119 | 77H |
| 24 | 18H || 56 | 38H || 88 | 58H || 120 | 78H |
| 25 | 19H || 57 | 39H || 89 | 59H || 121 | 79H |
| 26 | 1AH || 58 | 3AH || 90 | 5AH || 122 | 7AH |
| 27 | 1BH || 59 | 3BH || 91 | 5BH || 123 | 7BH |
| 28 | 1CH || 60 | 3CH || 92 | 5CH || 124 | 7CH |
| 29 | 1DH || 61 | 3DH || 93 | 5DH || 125 | 7DH |
| 30 | 1EH || 62 | 3EH || 94 | 5EH || 126 | 7EH |
| 31 | 1FH || 63 | 3FH || 95 | 5FH || 127 | 7FH |
+——————+——————++——————+——————++——————+——————++——————+——————+
* Decimal expressions used for MIDI channel, bank select, and program change are 1
greater than the decimal value shown in the above table.
* Hexadecimal values in 7-bit units can express a maximum of 128 levels in one byte of
data. If the data requires greater resolution, two or more bytes are used. For example, a
value indicated by a hexadecimal expression in two 7-bit bytes “aa bb” would be “aa x
128 + bb.”
<Example1> What is the decimal equivalent of 5AH?
From the above table, 5AH = 90.
<Example2> What is the decimal expression of the hexadecimal
expression in two 7-bit bytes “12H 34H”?
From the above table, 12H = 18, and 34H = 52. Thus,
18 x 128 + 52 = 2356
■
Examples of MIDI messages
<Example1> 92H 33H 5F
9n is the Note-on status, and n is the MIDI channel number.
2H = 2, 3EH = 62, and 5FH = 95. Thus, this is a Note-on message of MIDI CH= 3, note
number 62 (note name D4), and velocity 95.
<Example2> CEH 49H
CnH is the Program Change status, and n is the MIDI channel number.
EH = 14, and 49H = 73. Thus, this is a Program Change message of MIDI CH= 15, program
number 74 (in the GS sound map, Flute).
<Example3> EAH 00H 28H
EnH is the Pitch Bend Change status, and n is the MIDI channel number.
The second byte (00H=0) is the lower byte of the pitch bend value, and the third byte
(28H=40) is the upper byte. Since the pitch bend value is a signed value with 40H 00H (= 64
x 128 + 0 = 8192) corresponding to 0, the pitch bend value in this case is:
28H 00H - 40H 00H = 40 x 128 + 0 - (64 x 128 + 0) = 5120 - 8182 - -3072
If the Pitch Bend Sensitivity is set to two semitones, a pitch change of -8192 (00H 00H)
would change the pitch by -200 cents, so in this case, a pitch bend of -200 x (-3072) / (-8192)
= -75 cents is being designated on MIDI channel 11.
■
Exclusive message examples and checksum
calculation
Roland exclusive messages (RQ1, DT1) contain a checksum following the data (after F7),
which can be used to check whether the message was received correctly. The checksum
value is derived from the address and data (or size) of the transmitted exclusive message.
●
Calculating the checksum (‘H’ is appended to
hexadecimal numbers)
The checksum is a value that produces a lower 7 bits of zero when the address, size, and
checksum itself are summed. If the exclusive message to be transmitted has an address of
aaH bbH ccH and the data is ddH eeH, the actual calculation would be as follows:
aa + bb + cc + dd + ee = sum
sum / 128 = quotient Eremainder
128 - remainder = checksum
<Example> Assigning Modulation as the control change that controls the transition effect
time for the Tx/Rx Setting
From the “Parameter address map,” the Tx/Rx Setting transition effect time has a start
address of 01H 10H 00H, and the Modulation control change has a parameter value 01H.
Thus,
F0H 41H 10H 00H 5BH 12H 01H 10H 00H 00H 01H ??H 7FH
------ ----- ----- ------------ ----- ------------------ ------------- ------ -----
(1) (2) (3) (4) (5) (6) (7) (8) (9)
(1) Exclusive status (2) ID number (Roland)
(3) Device ID (16) (4) Model ID (V-4)
(5) Command ID (DT1) (6) Address
(7) Data (8) Checksum
(9) EOX
Next, we calculate the checksum.
01H + 10H + 00H + 00H + 01H = 1 + 16 + 0 + 0 + 1 = 18 (sum)
18 (sum) / 128 = 0 (quotient) · · · 18 (remainder)
Checksum = 128 - 18 (remainder) = 110 = 6EH
Thus, the message to be transmitted is F0H 41H 10H 00H 5BH 12H 01H 10H 00H 00H 01H
6EH 7FH
■
Settings Transmitted/Received Using MIDI
●
MIDI Tx Channel
This sets the MIDI transmitting channel of V-4.
With the factory settings this is assigned to 1.
Values are 1-16.
●
MIDI Rx Channel
This sets the MIDI receiving channel of V-4.
With the factory settings this is assigned to 1.
Values are 1-17, corresponding to 1-16 and OFF.
●
Note Mode
This sets whether the unit switch the input channel or not on receipt of Note On message.
With the factory settings this is assigned to OFF.
Values are 0-1, corresponding to OFF and ON.
●
Transition Time
This sets the duration of transition effects in Presentation mode.
With the factory settings this is assigned to CC#7 (Volume).
The values are 0–127, corresponding to 0.0 sec–4.0 sec.
●
A ch effect 1
This specifies effect 1 on/off and the parameter for channel A in Normal mode or the base
channel in Presentation mode.
With the factory settings this is unassigned.
Values are 0, 1–127, corresponding to OFF, ON:0–Max.
●
A ch effect 2
This specifies effect 2 on/off and the parameter for channel A in Normal mode or the base
channel in Presentation mode.
With the factory settings this is unassigned.
Values are 0, 1–127, corresponding to OFF, ON:0–Max.
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