Beeper

A built-in beeper is provided that beeps when touchscreen buttons are pressed, or based on app control.

The beeper device /dev/cardbeep accepts formatted strings containing various notes to play. The following notes are supported:

Note	Octave	Frequency (Hz)
C	5	523.25
D	5	587.33
E	5	659.26
F	5	698.46
G	5	783.99
A	5	880
B	5	987.77
C	6	1046.5
E	6	1318.5
G	6	1568
A	6	1760
C	7	2093
D	7	2349.3
E	7	2637

A string can be formatted to send to the device in the format:

<duration><note><octave>
 * duration
  * 1 – 8, note = 1/duration
   * 1 = whole (1/1) note
   * 4 = quarter (1/4) note
   * 8 = eighth (1/8) note
 * note - letter from above table
 * octave - number from above table

Commas are used to separate note information, for example:

4A5,8E6

Plays a 1/4 note A in octave five then a 1/8 note E in octave 6.

The default octave may be set by:

O<octave>

Example:

O5,A,B,C

Sets the default octave to 5 then plays note A, B, and C.

The tempo may be set by:

T<tempo>

tempo must be three characters numeric

Example:

T100,A,B

Sets the tempo to 100 then plays note A and B.

Refer to the lib825ev library PlayNotes function for application beeper output.