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Chapter 3: Programming 3-11
Key
Number Usage
FPGA
Offset
FPGA
Offset
Key
Number Usage Usage
FPGA
Offset
Key
Number
126 0 124 125 127 0 E4 118 77
127 0 125 126 72 E5 E5 126 72
128 0 127 127 128 0 E6 110 76
Configurable Key Click Tone
The FPGA has the ability to sound a short chirp whenever a key is
pressed, providing auditory feedback to an operator of the keyboard.
This auditory feedback is optional. The FPGA may be configured to
make the sound or not to make the sound, depending on the particular
application.
USB Keyboard Tone Frequencies
The frequency is transmitted to the FPGA as a Note Number . Note
numbers are equivalent to specific frequencies. The note number sent
to the FPGA is selected by rounding the requested frequency to the
nearest frequency number given by the table of Note Numbers (
N ) and
Frequencies ( freq ) listed in the following table.
Table 2: Note Numbers and Frequencies
Note N freq N freq N freq N freq N freq N freq
A
0 28 24 110 48 440 72 1760 96 7040 120 28160
Bb
1 29 25 117 49 466 73 1865 97 7459 121 29834
B
2 31 26 123 50 494 74 1976 98 7902 122 31609
C
3 33 27 131 51 523 75 2093 99 8372 123 33488
Db
4 35 28 139 52 554 76 2217 100 8870 124 35479
D
5 37 29 147 53 587 77 2349 101 9397 125 37589
Eb
6 39 30 156 54 622 78 2489 102 9956 126 39824
E
7 41 31 165 55 659 79 2637 103 10548 127 42192
F
8 44 32 175 56 698 80 2794 104 11175