1. Arduino MIDI Processing

2. MIDI and OSC
MIDI: is a technical standard that describes a communications protocol, digital interface, and electrical connectors that connect a wide variety of electronic musical instruments, computers, and related music and audio devices.
MIDI carries event messages that specify notation, pitch, velocity, vibrato, panning, and clock signals (which set tempo). For example, a MIDI keyboard or other controller might trigger a sound module to generate sound produced by a keyboard amplifier.
A file format that stores and exchanges the data is also defined.
Advantages of MIDI include small file size, ease of modification and manipulation and a wide choice of electronic instruments and synthesizer or digitally-sampled sounds.

3. MIDI and OSC MIDI technology was standardized in 1983.
All official MIDI standards are jointly developed and published by the MIDI Manufacturers Association MMA in Los Angeles, and the MIDI Committee of the Association of Musical Electronics Industry (AMEI) in Tokyo.
In 2016, the MMA established the MIDI Association (TMA) to support a global community of people who work, play, or create with MIDI.

4. BASIC Arduino

5. Subjects Covered Arduino Architecture.
Process of Development of Audio Applications.
Requires Basic knowledge of C language.
Functions
Structures
if statements
for – loops
etc.

6. Basic Architecture of Arduino
Arduino Architecture
Processor
Communications
Peripherals
User I/O - Pins
Power Supply & Control
Computer
Power Supply
Basic Architecture of Arduino
The processor
Communications
User I/O Pins
Power Supply Control
Peripherals

7. Arduino Processors Based on original Atmega x8 processor.
8 – bit processor
Today we have various architectures that are based on:
8 – bit
16 - bit
32 – bit

10. Arduino Processors Variety of processor have different:
Flash memory sizes: Flash memory is used to store the program
Data Sizes: Static Random Access Memory - SRAM
Electrically Erasable Programmable Read Only Memory – EEPROM
Variety of processors support various configurations such as:
32uX series that supports USB
SAM3X8E ARM Cotrex-M3 – this provides step up in processor technology and power
Arduino Yun that runs Linux with two core processors.

11. Communications Block
Communicating with the computer is performed over this block.
Typically is a USB/Serial Converter
Some of the chips sets do not have this module and it requires users to provide this function separately if needed.

12. User I/O Pins
The basic Arduino is capable to being expanded to an almost unlimited number of pins.
The use of the word “pin” to mean a single input/output line is unique to the Arduino and is sometimes confused with a physical pin on a chip.
This in turn has given flexibility to build various Arduino lines where the physical pin assignment is done in software configuration step.

13. Power Supply Control Block
Power can be provide to Arduino in two ways:
Via USB
Specific power supply.
Modern Arduinos detect automatically the source of the power

14. Onboard Peripherals Two kinds of peripherals: Inside the processor, &
Mounted on the Arduino board.

15. Peripheral Inside the Processor
The processor peripherals:
Hardware counter/timer
Serial Ports
Pin Interrupts
Analog to Digital (A/D) converter.
For example Timer can be used to:
Produce a fixed frequency pulse Width Modulation (PWM) signal.
Various chips have a variety of number of timers:
From 3 timers that produce 2 pulses each (6 pulses total).
To variety of modes a and timers generating 15 PWMs

16. Board Peripherals Arduino Ethernet – has an Ethernet controller.
Arduino WiFi - has an a WiFi module build-in.
In addition to various board peripherals Arduino supports extension boards.

17. Arduino for Audio
The more powerful the base processor the better and it will make processing easier.
For example:
Shortcomings in terms of peripherals can be accommodated for by adding addional input/output pins using external chips.
This memory however, is not part of the general memory: it can not be used store variables or arrays and it can be used only to store data.
As of 2015 the best Arduino for use in audio projects is Arduino Due:
96K SRAM
A/D 12 – bit resolution (4096)
2 D/A

18. Basic MIDI

19. Basic MIDI Using the MIDI signal Understanding MIDI messages
Hardware handling of MIDI singles
Building a MIDI shield
Sending and Receiving MIDI messages
USB

20. Basic MIDI
Using MIDI is the simplest way to get the Arduino to interact with a MIDI supported devices: It is simple to send and receive messages over MIDI interface
MIDI specifies a language of interaction that is understood by an countless number of musical instruments and controllers.
MIDI provides a simple electrical interface and its is designed to be compatible with a wide variety of electronic systems.

21. What is MIDI? MIDI – Musical Instrument Digital Interface
Introduced in 1983 with the goal to provide a standardized way to control musical instruments.
MIDI is designed with the goal of generality so that it can be applied to:
Lighting effect
Movement of various automation machinery
Movement of Robots, and more conventionally
For controlling applications involving music.

22. MIDI MIDI Standard – defines a protocol
MIDI Standard – defines an interface in terms of voltage, current, and connectors.

23. Electrical Signals
MIDI is defined as an asynchronous serial interface that uses Speed of communication – kHz
Chips that use Universal Asynchronous Receivers and Transmitters (UART), need a clock oscillator that is 16 time the required speed – baud rate.
UART chip has all the logic for sending and receiving and asynchronous data stream.
Arduino chips all have at lest one UART.

24. Electrical Signals of MIDI
Data is send Asynchronously one bit at a time.
Synchronization of transmitting and receiving streams is done every byte (8 – bits).

25. Electrical Signals of MIDI
MIDI Uses UART – Universal Asynchronous Receiver and Transmitter protocol.
UART communication requires synchronization step between Receiver and Transmitter. It utilizes 1MHz clock as a base clocking device. This clock then fed into divisor circuit to produce kHz signal.
The rate of communication ranges from:
300 boud
1200 boud
9600 bound …
Boud means “data bits per second”

26. Electrical Signals of MIDI
UART chip has the logic for sending and receiving an asynchronous data stream.
Each Arduino has at least one built in UART.
For example Arduino Mega have four UARTs
Synchronization of Receiver and Transmitter port is done after each byte (8 bits).
Start bit
Stop bit
Data
bit 0
Data
bit 2
Data
bit 4
Data
bit 6
Data
bit 1
Data
bit 3
Data
bit 5
Data
bit 7

27. Electrical Signals of MIDI
Optional extra bit that comes bewtween the last data bit and the stop bit – parity bit.
Parity bit if used will be chosen so that there is an odd or even number of data bits.
Note that in MIDI signaling parity bit is not used.
There a number of options is UART communications:
5,7, or 8 bits
Odd , Even or no parity,
1, 1 *1/2 or 2 stop bits

28. Electrical Signals of MIDI
For MIDI communication requires 0 stop bits to be send, and 8 bits of data to be transmitted.

29. MIDI Messages
In order to control a MIDI device, several bytes are combined to form a MIDI message.
The number of bytes required varies based on the content of the message.
There are a number of classes of MIDI messages to control various aspects of music system.
Each MIDI connection can communicate with its MIDID channels. Each MIDI device can be set to be one or several different MIDI channels.
Typically there are some switches on the device that control which channel it is on.

30. MIDI Messages
The channel number is embedded in the first byte of the MIDI message as the four least significant bits.
Message's first byte contains two pieces of information:
The channel number, what kind of message it is.
How many other bytes make the whole message
The first by of MID message is often called the “status byte”.
In the case of the note, there are tow other bytes associated with this message as displayed next.

31. MIDI Messages
The anatomy of a note on message

32. MIDI Messages First MIDI message has the most significant bit set.
All subsequent messages start with most significant bit set to zero.

33. MIDI Messages The two other bytes in the MIDI message contain
the note numbed
and the velocity (or how hard the note is struck)
Because the first most significant bit is reserved for message only, the range of values contained in the message is
Because this is insufficient in order to generate all the notes:
Note’s timber
is another ‘quality’ of sound that is required to be set for some instruments.
Sound color of piano changes depending on how hard you hit the key.

34. ‘Note on’ and ‘Note off’
‘Note on’ message is almost always accompanied by a matching ‘Note off’ message.
We sow in previous slides how the details of ‘Note on’ message.
The MIDI system allowas two ways of turning a note off.
It’s own note off message, with data being the note number and the velocity being how quickly it was released.
Some devices may ignore this value while other ones may set it to a fixed value typically set to 0.
Turning a note off message by seinding a note on message with note on velocity set to 0.

35. ‘Note on’ and ‘Note off’
Any system receiving MID should be capable of coping with both methods of running a note off.
If there is not a note off message that matches a previous note on message, a note can become stuck.

36. Hexadecimal Notation Sign Magnitude One’s Complement Two’s Complement
There are several different binary number representational conventions for signed and unsigned numbers. Most notable are: .
Hexadecimal Notation
Decimal Value
Sign Magnitude
One’s Complement
Two’s Complement +7
0111 +6
0110 +5
0101 +4
0100 +3
0011 +2
0010 +1
0001 +0
0000 -0
1000
1111 - -1
1001
1110 -2
1010
1101 -3
1011
1100 -4 -5 -6 -7 -8
Sign Magnitude
One’s Complement
Two’s Complement
Example of 4-bit signed numbers is presented in the Table for three formats listed above:
Example Table of 4 bit number representations

37. Hexadecimal Notation Binary Decimal Hexadecimal 0000 0001 1 0010 2
0001 1
0010 2
0011 3
0100 4
0101 5
0110 6
0111 7
Binary
Decimal
Hexadecimal
1000 8
1001 9
1010 10 A
1011 11 B
1100 12 C
1101 13 D
1110 14 E
1111 15 F

38. MIDI Connections There are 3 types of MIDI sockets on the device:IN
OUT
THRU
When connecting different devices, a MIDI OUT must be connected to a MIDI IN.
MDI THRU is a copy of the single on the MIDI IN and can be used chin one MIDI OUT to several device:

39. MIDI Connections

40. Arduino Implementation of MIDI
Arduino has a UART built in.
It uses it to upload music and send and receive serial data.
By setting appropriate serial interface to the correct bound rate, one can
Send to,
Listen to,
any standard MIDI device.

41. Software MIDI Output
Driving MIDI is done through a C program described next:
/* Generating MIDI output * Sending MIDI serial data, automatically for a test */ # define midiChannel (byte) 0 // Channel #1 void setup() { // Setting up Serial Port (UART) Serial.begin(31250); // MIDI Speed } void loop() { int val; val = random(20, 100); noteSend(0x90, val, 127); // note on delay(200); noteSend(0x80, val, 127); //note off delay(800); // playing a MIDI note void noteSend(char cmd, char data1, char data2) { cmd = cmd | char(midiChannel); // merge channel number Serial.write(cmd); Serial.write(data1); Serial.write(data2);

42. Software MIDI Input /* MIDI Input * Listen for MIDI Serial Port */
byte channel = 1; // MIDI channel - #2
void setup() {
pinMode(13, OUTPUT); // LED to light up
digitalWrite(13, LOW); // Turn LED off
Serial.begin(31250); // start serial port }
void loop () {
checkIn(); // input arrivals
void checkIn() {
static int state = 0; // 0 – command waiting
// 1 – note waiting
// 2 – velocity waiting
static char note = 60;
static Boolean noteDown = LOW;

43. if (Serial.avialble() > 0) {
byte icommingByte = Serial.read();
switch (state) {
case 0:
// status-byte, note on
if (incommingByte ==
( 0x90 | channel)) {
noteDown = HIGH;
state = 1; }
// status-byte, note off
( 0x80 | channel)) {
noteDown = LOW;

44. case 1:
// note to play or stop
if (incommingByte < 128) {
note = incommingByte;
state = 2; }
else {
state = 0
break;
case 2:
doNote(note, incommingByte, noteDown);
state = 0; // reset state machine

45. Software MIDI Input
void doNote(byte note, byte velocity, boolean down) { // if velocity = 0 on a ‘Note ON’ command, treat it as a note off if ((down == HIGH) && 9velocity == 0)) { down = LOW); } // doing something with a note message // toggling Pin 13 and ignoring the note value and velocity digitalWrite(13, down);

46. Additional Notes on MIDI

47. Additional Notes on MIDI
We have seen previously the implementation on NOTE ON and NOTE OFF messages.
They are going to be essential in playing the notes (sounds).
MIDI controller is a device that can control an aspect of a sound:
Volume,
Vibrato,
Position of the instrument on a stage, etc.
Two types of messages:
A channel message aimed a one playing channel, and
A system message aimed at the whole system.

48. Additional Notes on MIDI
There are 5 types of channel messages related to voice.
Note on/Note off
Controller change
Program Change
Pitch bend
Aftertouch

49. Additional Notes on MIDI
We already have discussed note on/note off messages.
For full specification of MIDI see this web site:

50. Controller Change MIDI Messages
A method for providing a control change.
Up to 120 controllers on each MIDI channel.
Associated with each channel is a number with a value between 0 – 127.
Controller channel usages:
ON/OFF switching, etc. 1
Message
Top bit set means this is
a message number
Channel
Value = 11 = 0xB
Controller Change
Value = 2 = 0x2
Chanel 3

51. Controller Change MIDI Messages1 1 1 1 1
Top bit is set to 0
It means is a data value
Value = 61 = 0x3D
Controller 61 1
Value = 64 = 0x40
Controller 64

52. Controller Change MIDI Messages
Controller Channel (CC) message: CC120 (all sounds off) and CC123 (all notes off) look rather similar.
The CC123 message will have no effect on a note sustained due to unresolved CC64 (sustain peddle hold) or CC65 (Partamento Pedal).
As opposed to CC120 that will change the effect.

53. Controller Channel Message
Value
Meaning
120
All sounds off – turn all notes on this channel off.
121
Reset all controllers to their default values.
122
Local control off – respond only to MIDI messages.
127
Local control on – respond to local inputs like a keyboard.
123
All notes off.
124
Omni mode off.
125
Omni mode on.
126 M
Mono mode on (poly mode off) where M is the number of channels
Poly mode on (mono mode off).
Mote the last four message also cause all notes to be off.

54. Channel Controller Messages
Recommended standard that helps interconnectivity as shown in the next Table.
Controller Number
Function
Bank Select MSB 32
Bank Select LSB 1
Modulation MSB 33
Modulation LSB 2
Breath Control MSB 34
Breath Control LSB 4
Foot Pedal MSB 36
Foot Pedal LSB 5
Portamento Time MSB 37
Portamento Time LSB 6
Data Entry MSB 38
Data Entry LSB 7
Channel Volume MSB 39
Channel Volume LSB 8
Balance MSB 40
Balance LSB 10
Pan MSB 42
Pan LSB 11
Expression MSB 43
Expression LSB 12
Effect-Type Selector #1 44
Undefined

55. 13
Effect-Type Selector #2 45
Undefined 16
General Purpose 1 MSB 48
General Purpose 1 LSB 27
General Purpose 2 MSB 49
General Purpose 2 LSB 28
General Purpose 3 MSB 50
General Purpose 3 LSB 29
General Purpose 4 MSB 51
General Purpose 4 LSB 64
Sustained Pedal (On/Off) 65
Portamento Pedal (On/Off) 66 67
Soft Pedal (On/Off) 68
Legato Pedal (On/Off) 69
Hold 2 (On/Off) 70
Sound Control 1 (Sound Variation) 71
Sound Control 2 (Harmonic Content) 72
Sound Control 3 (Release Time) 73
Sound Control 4 (Attack Time) 74
Sound Control 5 (Brightness)
75-79
Sound Control 6-10 (Undefined)

56. Controller Number
Function 80
General Purpose 5 81
General Purpose 6 82
General Purpose 7 83
General Purpose 8 84
Portamento Control 91
Reverb Depth 92
Tremolo Depth 93
Chorus Depth 94
Celeste Detune Depth 95
Phaser Depth 96
Data Increment 97
Data Depth 98
NRPN LSB 99
NRPN MSB
100
RPN LSB
101
RPN MSB

57. Program Change MIDI Messages
The program change message sets up the voice a MIDI sound module will play in.
It is a two-byte message:
First byte contains the message number and a channel
Second byte represents the number of the new voice. 1
Message
Top bit set means this is
a message number
Channel
Value = 14 = 0xC
Program Change
Value = 10 = 0x11
Chanel 11

58. Program Change MIDI Messages
Program Change Message 1
Top bit clear means this is
a data value
Value = 70 = 0x4D = Instrument 71 = Bassoon

59. General MIDI 1 Sound Set
General MIDI's most recognized feature is the defined list of sounds (or "patches").
Each manufacturer must insure that their sounds provide an acceptable representation of song data written for General MIDI.
The names of the instruments indicate what sort of sound will be heard when that instrument number (MIDI Program Change or "PC#") is selected on the GM1 synthesizer.
These sounds are the same for all MIDI Channels except Channel 10, which has only "percussion" sounds.
However, General MIDI does not actually define the way the sound will be reproduced, only the name of that sound. Though this can obviously result in wide variations in performance from the same song data on different GM sound sources, the authors of General MIDI felt it important to allow each manufacturer to have their own ideas and express their personal aesthetics when it comes to picking the exact timbres for each sound.

60. General MIDI 1 Sound Se
Just like channel numbers, instrument numbers run from (actual values range from 0-127).
General MIDI defines voice number ranges into families of instruments shown in the Table below.
Range
Family Name
1-8
Piano
9-16
Chromatic Percussion
17-24
Organ
25-32
Guitar
34-40
Bass
42-48
Strings
49-56
Ensemble
57-64
Brass
65-72
Reed
73-80
Pipe
81-88
Synth Lead
89-96
Synth Pad
97-104
Synth Effects
Ethnic
Percussive
Sound Effects

61. General MIDI Level 1 Instrument Families
The voices for the first group in the previous table, e.g., Piano, are split over the first eight values are shown in the Table below:
Range
Family Name 1
Acoustic Grand Piano 2
Bright Acoustic Piano 3
Electric Grand Piano 4
Honky-tonk Piano 5
Electric Piano 1 6
Electric Piano 2 7
Harpsichord 8
Clavi

62. General MIDI Level 1 Instrument Patch Map
Note: While GM1 does not define the actual characteristics of any sounds, the names in parentheses after each of the synth leads, pads, and sound effects are, in particular, intended only as guides).
PC#
Instrument Name 1.
Acoustic Grand Piano
20.
Church Organ 2.
Bright Acoustic Piano
21.
Reed Organ 3.
Electric Grand Piano
22.
Accordion 4.
Honky-tonk Piano
23.
Harmonica 5.
Electric Piano 1
24.
Tango Accordion 6.
Electric Piano 2
25.
Acoustic Guitar (nylon) 7.
Harpsichord
26.
Acoustic Guitar (steel) 8.
Clavi
27.
Electric Guitar (jazz) 9.
Celesta
28.
Electric Guitar (clean)
10.
Glockenspiel
29.
Electric Guitar (muted)
11.
Music Box
30.
Overdriven Guitar
12.
Vibraphone
31.
Distortion Guitar
13.
Marimba
32.
Guitar harmonics
14.
Xylophone
33.
Acoustic Bass
15.
Tubular Bells
34.
Electric Bass (finger)
16.
Dulcimer
35.
Electric Bass (pick)
17.
Drawbar Organ
36.
Fretless Bass
18.
Percussive Organ
37.
Slap Bass 1
19.
Rock Organ
38.
Slap Bass 2
39.
Synth Bass 1

63. 40.
Synth Bass 2
66.
Alto Sax
42.
Viola
67.
Tenor Sax
43.
Cello
68.
Baritone Sax
44.
Contrabass
69.
Oboe
45.
Tremolo Strings
70.
English Horn
46.
Pizzicato Strings
71.
Bassoon
47.
Orchestral Harp
72.
Clarinet
48.
Timpani
73.
Piccolo
49.
String Ensemble 1
74.
Flute
50.
String Ensemble 2
75.
Recorder
51.
SynthStrings 1
76.
Pan Flute
52.
SynthStrings 2
77.
Blown Bottle
53.
Choir Aahs
78.
Shakuhachi
54.
Voice Oohs
79.
Whistle
55.
Synth Voice
80.
Ocarina
56.
Orchestra Hit
81.
Lead 1 (square)
57.
Trumpet
82.
Lead 2 (sawtooth)
58.
Trombone
83.
Lead 3 (calliope)
59.
Tuba
84.
Lead 4 (chiff)
60.
Muted Trumpet
85.
Lead 5 (charang)
61.
French Horn
86.
Lead 6 (voice)
62.
Brass Section
87.
Lead 7 (fifths)
63.
SynthBrass 1
88.
Lead 8 (bass + lead)
64.
SynthBrass 2
89.
Pad 1 (new age)
65.
Soprano Sax
90.
Pad 2 (warm)

64. 91.
Pad 3 (polysynth)
116.
Woodblock
92.
Pad 4 (choir)
117.
Taiko Drum
93.
Pad 5 (bowed)
118.
Melodic Tom
94.
Pad 6 (metallic)
119.
Synth Drum
95.
Pad 7 (halo)
120.
Reverse Cymbal
96.
Pad 8 (sweep)
121.
Guitar Fret Noise
97.
FX 1 (rain)
122.
Breath Noise
98.
FX 2 (soundtrack)
123.
Seashore
99.
FX 3 (crystal)
124.
Bird Tweet
100.
FX 4 (atmosphere)
125.
Telephone Ring
101.
FX 5 (brightness)
126.
Helicopter
102.
FX 6 (goblins)
127.
Applause
103.
FX 7 (echoes)
128.
Gunshot
104.
FX 8 (sci-fi)
105.
Sitar
106.
Banjo
107.
Shamisen
108.
Koto
109.
Kalimba
110.
Bag pipe
111.
Fiddle
112.
Shanai
113.
Tinkle Bell
114.
Agogo
115.
Steel Drums

65. General MIDI Level 1 Percussion Key Map
On MIDI Channel 10, each MIDI Note number ("Key#") corresponds to a different drum sound, as shown below. GM-compatible instruments must have the sounds on the keys shown here. While many current instruments also have additional sounds above or below the range show here, and may even have additional "kits" with variations of these sounds, only these sounds are supported by General MIDI Level 1 devices.
Key#
Drum Sound 35
Acoustic Bass Drum 36
Bass Drum 1 37
Side Stick 38
Acoustic Snare 39
Hand Clap 40
Electric Snare 41
Low Floor Tom 42
Closed Hi Hat 43
High Floor Tom 44
Pedal Hi-Hat 45
Low Tom 46
Open Hi-Hat

66. 47
Low-Mid Tom 70
Maracas 48
Hi-Mid Tom 71
Short Whistle 49
Crash Cymbal 1 72
Long Whistle 50
High Tom 73
Short Guiro 51
Ride Cymbal 1 74
Long Guiro 52
Chinese Cymbal 75
Claves 53
Ride Bell 76
Hi Wood Block 54
Tambourine 77
Low Wood Block 55
Splash Cymbal 78
Mute Cuica 56
Cowbell 79
Open Cuica 57
Crash Cymbal 2 80
Mute Triangle 58
Vibraslap 81
Open Triangle 59
Ride Cymbal 2 60
Hi Bongo 61
Low Bongo 62
Mute Hi Conga 63
Open Hi Conga 64
Low Conga 65
High Timbale 66
Low Timbale 67
High Agogo 68
Low Agogo 69
Cabasa

67. Pitch Bend MIDI Messages

68. Changing the Pitch of a Note
Three-byte message, with two bytes of what follows form the 14-bit value. 1
Message
Top bit set means this is
a message number
Channel
Value = 14 = 0xC
Pitch Bend
Value = 15 = 0xE
Chanel 16
First byte (8 bit)

69. Changing the Pitch of a Note
Three-byte message, with two bytes that follow form the 14-bit value to use. 1
Top bit clear means this is
a data value
Value = 107 (or 0x68) 1 1 1
Value = 82 (or 0x52)
Second (8 bits) and Third (8 bits)

70. Changing the Pitch of a Note
Three-byte message, with two bytes that follow form the 14-bit value. The data format follows the “little endian” format with the LSB first. 1 1 1 1 1 1 1 1
Pitch Bend Value = 0x296B = 10603

71. Aftertouch MIDI Messages

72. Aftertouch Messages 1 Message Channel
The last of the channel voice messages is the Aftertouch message.
This message will determine how hard one presses down on the keys.
There are two types of Aftertouch message:
Monophonic (all keys have only one pressure-sensitive sensor)
Polyphonic (each key has individual pressure-sensitive sensor) 1
Message
Top bit set means this is
a message number
Channel
Value = 13 = 0xD
Aftertouch
Value = 0 = 0x0
Chanel 1
First byte (8 bit)

73. Aftertouch Messages 1
Top bit clear means this is
a data value
Value = 67 = 0x43 = Value of 67 = Pressure Value of 63
The pressure values do not correspond to any absolute measure; they are relative readings with 127 corresponding to highest value and 0 indicating the lightest of touchers. Note that if you change the pressure while holding donw a note, a new Aftertouch message will be generated.

74. System MIDI Messages

75. System MIDI Messages 1 Message Channel
The other class of MIDI messages is the system message. They are messages that target the whole System as opposed to individual channels.
With the system messages there is no need to specify channel and the lower part of the message now represents the type of system message. 1
Message
Top bit set means this is
a message number
Channel
Value = 15 = 0xF
System message
Reset

76. Anatomy of System Messages
Most of System Messages have only on byte; 0xFF.
There are three groups of system messages:
System real-time
System common
System exclusive

77. System Real-Time Messages
System Real-Time messages are used to synchronize the timing between several MIDI devices or between a device and a recording system.
Five types of messages:
System Reset (0xFF) – Device can wipe their memory clean.
MIDI Clock (0xF8) – it is send 24 times per quarter of a note. It is used as a metronome that forces the receiving device to keep the same time as the sending device.
Start (0xFA) , Stop (0xFC), Continue (oxF9) – Used for controlling sequences.
Active Sensing (0xFE) – This is optional command that once it is send the receiver will expect to see a message like this three times a second. If the receiver stops getting these messages, it assumes something is wrong and shuts down turning all notes off.
Reserved (0xF9) – This message is reserved for future revisions.

78. System Common Messages
Controlling and synchronizing other devices.
MIDI Time Code (0xF1 + one data) – This is 100 pulses per second system used to synchronize MIDI with audio or video.
Song Pointer (0x2 + two data) – This is a 14-bit value that records how many MIDI beats there have been since the start of the song. One MIDI beat consists of six MIDI clocks.
Song Selector (0xF3 + one data) – This specififies which sequence or song is to be played or in the case of a drum machine what chain of patterns.
Tune Request (0xF6) – A message to ask analogue synthesizer to retune their oscillators.
Reserved (0xF4 & 0xF5) – Two unused messages.

79. System Exclusive Messages
System Exclusive messages are the most complex messages on a MIDI system.
Those messages are typically used to tell devices to load or save sound samples or other data.
A device should only respond to its own manufacturers ID number.

80. ………………….. ………………….. ………………….. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
Top bit set means this is a message number 1 1 1 1
Value = 0xF0 = Start SysEx message
Top bit clear means this is data message 1 1 1 1
Value = 0x96 = Manufacturers ID code 1 1 1 1 1 1 1 1
…………………..
…………………..
Other bytes of data
………………….. 1 1 1 1 1 1 1
Value = 0xF7 = End SysEx message