Roland VR-4HD Reference Manual page 36

MIDI Implementation
4. Supplementary Material
z Decimal and Hexadecimal Table
„
(Hexadecimal Numbers are Indicated by 'H')
In MIDI documentation, data values and addresses/sizes of exclusive messages etc.
are expressed as hexadecimal values for each 7 bits.
The following table shows how these correspond to decimal numbers.
+——————+——————++——————+——————++——————+——————++——————+——————+
| D | H || D | H || D
+——————+——————++——————+——————++——————+——————++——————+——————+
| 0 | 00H || 32 | 20H || 64 | 40H ||
| 1 | 01H || 33 | 21H || 65 | 41H ||
| 2 | 02H || 34 | 22H || 66 | 42H ||
| 3 | 03H || 35 | 23H || 67 | 43H ||
| 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 |
+——————+——————++——————+——————++——————+——————++——————+——————+
D: decimal
H: hexadecimal
* 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 bbH
would be aa x 128 + bb.
* Data marked "nibbled" is expressed in hexadecimal in 4-bit units. A value expressed
as a 2-byte nibble 0a 0bH has the value of a x 16 + b.
<Example1>
What is the decimal expression of 5AH?
From the preceding table, 5AH = 90
<Example2>
What is the decimal expression of the value 12 34H given as hexadecimal for each 7
bits?
From the preceding table, since 12H = 18 and 34H = 52
18 x 128 + 52 = 2356
<Example3>
What is the decimal expression of the nibbled value 0A 03 09 0D?
From the preceding table, since 0AH = 10, 03H = 3, 09H = 9, 0DH = 13
((10 x 16 + 3) x 16 + 9) x 16 + 13 = 41885
<Example4>
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.
36
| H || D | H |
96 | 60H |
97 | 61H |
98 | 62H |
99 | 63H |
z MIDI Message Examples
„
<Example 1> 92H 3EH 5FH
9n is a note on status and n is the MIDI channel number.
As 2H = 2, 3EH = 62 and 5FH = 95, this is a note on message of MIDI CH =3 , note
number 62 (D4) and velocity 95.
<Example 2> CEH 49H
CnH is program change status, and n is the MIDI channel number.
As EH = 14 and 49H = 73, this is a program change message of MIDI CH = 15 and
program number 74 (in the GS sound map, Flute).
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 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 aa bb ccH and the data is dd ee ffH, the actual calculation would be as
follows:
aa + bb + cc + dd + ee + ff = sum
sum / 128 = quotient ... remainder
128 - remainder = checksum
(However, the checksum will be 0 if the remainder is 0.)
<Example>
Setting Dissolve Time Ctrl Assign in MIDI Visual Control to Modulation for Control
Changes
From the "Parameter Address Map", the start address of the Dissolve Time Ctrl Assign
in MIDI Visual Control is 10H 10H 02H and the Modulation parameter in Control
Change is 00H 01H. Therefore ...
F0H 7EH 00H 0CH 01H
(1) (2) (3) (4)
(1) Exclusive Status
(2) ID Number (Universal SysEx Non Realtime)
(3) Device ID (0)
(4) Sub ID (MIDI Visual Control Version 1.0)
(5) Address
(6) Data
(7) Checksum
(8) EOX
Next calculate the checksum. Add (5) to (6).
10H + 10H + 02H + 00H + 01H = 16 + 16 + 2 + 0 + 1 = 35 (sum)
35 (sum) / 128 = 0 (quotient) ... 35 (remainder)
Checksum = 128 - 35 (remainder) = 93 = 5DH
Thus, the message to transmit is :
F0H 7EH 00H 0CH 01H 10H 10H 02H 00H 01H 5DH F7H
10H 10H 02H 00H 01H ??H
(5) (6) (7)
F7H
(8)