阿蘭

簡介

深受美秀集團自製樂器「台八線」啟發，揉合心中對於電子訊號與手作的熱愛後誕生。阿蘭的演奏方式為再譯人聽音樂的肢體動作，應用感測裝置、Arduino、開源合成器VCV Rack、圈型LED燈來創造一種新型態的樂器演奏體驗。阿蘭的本體由透明壓克力管手工打造，管身上方分別有可以演奏八度音的音高按鈕，以及三段式的音色控制鈕；管身前端為可以變化背景Sequencer的切換器，為阿蘭帶來獨立演奏或是樂團中配器的兩種角色。手作電子樂器——阿蘭隸屬於交大「學生自主學習社群」計畫創新實作研究類，並會持續進化成易用性與酷炫性兼具的自製樂器。

Demo 影片

社群帳號

• Instagram

Technical Details

Midi Map

Reciever to VCV

• [CC] Control #0 ~ Control #3 are used to change program. (top switch)
• [CC] Control #4 is for the mapped value of accelerometer measurement.
• [CC] Control #8 ~ Control #10 are for buttons.
• [CC] Control #12 ~ Control #14 is for the 2 way switch.
• [CV] Buttons are used to perform different note with different combinations. (val2note in reciever.ino)

VCV to Reciever

• [CV] VCV pass a value to reciever through channel #1 MW.

Data Format between 2 Sparkfun Pro Micro

lan to Reciever

• Each data is a 16-bit integer,
  • The first 8 bits from the high bits represent the shaking time.
    • Bit 7 is currently not in used.
    • Bit 0~6 is an interger mapping from ( 20 ms ~ 2000 ms ) to ( 0 ~ 127 ).
    • The value is decided by the define part of lan.ino.
  • The last 8 bits represent the button and switch states.
    • Bit 0 from the low bits represent the state of button 1.
    • Bit 1 from the low bits represent the state of button 2.
    • Bit 2 from the low bits represent the state of button 3.
    • Bit 3 and bit 4 from the low bits represent the state of the 2-way switch.
      • only 3 values are used, which are 00, 01 and 10.
    • Bit 5 and bit 6 from the low bits represent the state of the top switch (program).
    • The 7 bit is currently not in used.

Reciever to lan

• The reciever read BPM from VCV Rack, than pass this value to lan.
  • The relation between BPM and read value is a exponential function. data here
  • Each data contains only 1 16-bit integer which represents BPM ranging from 60 ~ 540.
  • Note that the calculated BPM has an error to the real value caused by the resolution of midi control level.

Light Pattern

Pattern 1 - simple RGB

Pattern 2 - Circle RGB

Pattern 3 - Random

Calculations of Imu.

• The calculation of imu used only accelerometer.
  • In imu.hpp
    • First, it calculates the root-mean-square value of y-axis reading and z-axis reading since the x-axis is parrallel to the lan itself.
    • Second, it finds 2 time neighbhoring steps whose values are across 0 as critical time steps.
    • Third, it calculates the length of the 2 most recent critical time steps.
  • In lan.ino
    • The length is mapped from 2 ( *10ms ) ~ 200 ( *10ms ) to 0 ~ 127.
    • Then a simple low pass filter is applied.
• The Result can be shown below.
  • 
  • The blue line and red line represents the yz-value reading.
  • The green line is the length of the 2 most recent critical time steps.
  • The orange line is the filtered value.

TODO

Bugs

• The 2-way switch will affect the light pattern

Members

啟萱、宣堯、修瑋