# Notes

## Plan
- [ ] Test speaker without Arduino
 - can be done by using a function generator and 3.3V square wave
   with variable frequency
- [ ] Write AVR C code to generate a square wave of varying frequency
   via Timer1
 - Timer1 is used so that a pre-scalar and its calculations don't
   need to be done
- [ ] Use a table/array that stores frequencies and the indices correspond to
   the buttons on the sound board
- [ ] Create buffers to add recording/saving/playing functionality
 - the buffers are a sequence of notes (which are the indices of the previous
   table) that is terminated by some other byte
- [ ] Figure out how the LCD in the starter kit is programmed
- [ ] Show the current and surrounding notes in the currently selected buffer
   (or the note of the soundboard button that was just pressed)
- [ ] Add a menu on the second row to select the memory buffer (maybe 1-5)
 - it is controlled by left and right buttons

## 2024-03-28
![](2024-03-28_notes.jpg)

## 2024-03-30
- the speaker was tested with a function generator (from the
  EspoTek Labrador) outputting a square wave of varying frequency
- it is painful above a frequency of 12 kHz and just creates clicks
  below 30 Hz
- it is louder at certain frequencies and quieter at others, and this
  is not a linear relationship
 - the speaker's datasheet has a graph of this which can be used to
   adjust the speaker's volume at the problematic frequencies

## 2024-04-03
- other speakers sold on DigiKey have more stable frequency response
  graphs where the volume does not fluctuate very much compared to the
  speaker included in the kit
- those speakers however use sine waves instead of square waves, so our
  first step should be focused on figuring out how to send sine waves at
  certain frequencies, perhaps with fast PWM