Yamaha disklavier MX-100A, Product Handbook

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Principle of Sensor Emission & Reception
The Key Emission sheet incorporates 12 LEDs, where each LED is assigned to a different key in the scale: from
A to G#. The Key Receive sheet incorporates 8 photoreceptors, one for each octave. The combination of LED and
photoreceptor uniquely identifies each key on the keyboard.
Emission & Reception Design
The 12 LEDs fire sequentially, from A to G#. (They do not fire simultaneously.) The receiving side detects the
octave, thereby uniquely identifying the key.
LED
Sequential
firing
1A 2A# 3B 4C 5C# 6D 7D# 8E 9F 10F# 11G 12G#
1A 2A# 3B 4C 5C# 6D 7D# 8E 9F 10F# 11G 12G# 1
13A 14A# 15B 16C 17C# 18D 19D# 20E 21F 22F# 23G 24G#
13A 14A# 15B 16C 17C# 18D 19D# 20E 21F 22F# 23G 24G# 2
25A 26A# 27B 28C 29C# 30D 31D# 32E 33F 34F# 35G 36G#
25A 26A# 27B 28C 29C# 30D 31D# 32E 33F 34F# 35G 36G# 3
37A 38A# 39B 40C 41C# 42D 43D# 44E 45F 46F# 47G 48G#
37A 38A# 39B 40C 41C# 42D 43D# 44E 45F 46F# 47G 48G# 4
49A 50A# 51B 52C 53C# 54D 55D# 56E 57F 58F# 59G 60G#
49A 50A# 51B 52C 53C# 54D 55D# 56E 57F 58F# 59G 60G# 5
61A 62A# 63B 64C 65C# 66D 67D# 68E 69F 70F# 71G 72G#
61A 62A# 63B 64C 65C# 66D 67D# 68E 69F 70F# 71G 72G# 6
73A 74A# 75B 76C 77C# 78D 79D# 80E 81F 82F# 83G 84G#
73A 74A# 75B 76C 77C# 78D 79D# 80E 81F 82F# 83G 84G# 7
85A 86A# 87B 88C
85A 86A# 87B 88C 8
Emission Sheet Receive Sheet
Example: Detection of Key 25A
Sensor
A#
B
C
C#
D
D#
E
F
F#
G
G#
A