Control individually addressable LEDs using the FastLED library and USB MIDI using the Teensy 3.6
See a demo and video of construction here: https://www.youtube.com/watch?v=1hBeVJ6QlaU
Requires a Teensy device. I am using a Teensy 3.6. I programmed it via Teensyduino configuring as a USBMIDI device:
The PSU must be rated for power required by your LED strips. Each LED with each color at full brightness (white) can be estimated to draw 50mA. 108 LEDs as I have programmed has a current draw of 108 lights * 0.05 Amps/light = 5.4A. 5V * 5.4A = 27W minimum for the power supply you shoudl buy. You should get a PSU that can output a good margin more power than is required (although it will only supply as much power as is demanded from the lights).
You will require an Digital Audio Workstation to send MIDI control messages. To use the included template/example, you will need FL Studio (I'm using version 20)
The Teensy will need to be connected as shown below:
In the code: Enter the total number of RGB LEDs under the NUM_LEDs definition and enter the pin from which data will be sent to the lights under the DATA_PIN definition.
Upload the code to the board, leave the usb cable connected, and then turn on the 5V PSU.
Start FL Studio and press play!
Void loop will write messages to the lights at a frequency of 1/33,333e-6s = ~30Hz Between writes to the data line, the HSV of each light is determined by midi event handlers OnNoteOn, OnNoteOff, and (most usually) OnControlChange. On Control change is used to directly set the value of several global variables as described at the bottom. The global parameters are used differently or ignored depending on the mode - the parameter with the most effect on how LEDs are displayed. Several modes have been programmed - Their names are given in the OnControlChange function, but the best way to figure out what they do is to try them out!
In order to make it more visually interesting, I've incorporated the concept of a foreground and a background. We'll call them layers. If the foreground doesn't make use of all of the lights, then the background will cover the rest. This way, you can control two sets of patterns simultaneously and independently. It's possible to do more patterns than this, but having an foreground an background seemed intuitive and manageable.
Global variables are bytes since MIDI standard only allows numbers between 0 and 127 to be transmitted. some variables don't make use of all 127 values, i.e. ffMode has 9 values - 0,1,2,3,4,5,6,7,8 These variables generally control these aspects of the LEDs:
Parameter | MIDI Control # | Description
ffHue | 1 | foreground layer hue
ffSat | 2 | foreground layer saturation
ffBright | 3 | foreground layer brightness
ffLedStart | 4 | foreground layer start position of LED
ffLedLength | 5 | foreground layer length of a line of LEDs
ffMode | 6 | foreground layer mode (0-8)
// 0: notes2MIDIChannel
// 1: rainbow wheel
// 2: moving dots
// 3: comets
// 4: back and forth
// 5: Move startLED with each note on event
// 6: Color Sinusoid
// 7: Stadium Camera flashes
// 8: Ocean waves
// 9: Opposed Ocean waves
lines | 7 | foreground layer number of LED lines
cAmp | 8 | foreground and background layer color Amplitude for use in color sinusoid mode (my favorite)
bgMode | 9 | background layer mode (0-2)
//0: Flat Color background
//1: rainbow wheel background
//2: Color Sinusoid
pan | 10 | used in ffMode "Ocean Waves"
bgHue | 11 | background layer hue
bgSat | 12 | background layer sat
bgBright | 13 | background layer brightness
bgLedStart | 14 | background layer start position of LED
bgLedLength | 15 | background layer length of line of LEDs
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Click on the Lights MIDI Channel to show the control knobs. You can right click the control knobs and click Configure to show that e.g. sat has Controller set to 2, so that the value of sat in Fl Studio is assigned to ffSat on the Teensy.
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Ensure that the port is the same as what is configured for the MIDI device (Check MIDI settings by pressing F10)
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You can access Foreground and Background controls on separate pages accessible by this dropdown
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You can right click a control knob and select create automation clip to be able to automate that property temporally.
The code uses structured comments to define MIDI parameters and modes. The generate_csv.py script automatically parses these comments to create Template.csv for FL Studio.
- Add a metadata block in
lights.inobefore the variable declaration:
/**
* @param MyParameter
* @cc 16
* @layer Foreground
* @tooltip Description of what this parameter does
*/
int myVar = 0;- Add a case to the
OnControlChangeswitch statement:
case 16: myVar = value; break;-
Use the variable in one or more mode implementations
-
Regenerate the CSV:
python generate_csv.py
- Add the mode name to the appropriate mode selector's
@modeslist:
/**
* @param Foreground
* @cc 6
* @modes 0:Notes to Drives,...,10:MyNewMode
*/- Implement the mode logic in the appropriate switch statement with a mode annotation:
case 10: // @mode MyNewMode @uses ffHue,ffSat,ffBright,myVar
// Your mode logic here
break;- Regenerate the CSV:
python generate_csv.py
@param DisplayName- Name shown in FL Studio@cc N- MIDI Control Change number (1-15, or higher if MIDI allows)@layer Foreground|Background|Shared- Which layer uses this parameter (omit for mode selectors)@tooltip Description- Help text for the parameter@modes N:ModeName,M:OtherMode- For mode selectors only, lists available modes@mode ModeName @uses var1,var2- Annotates a case statement with mode info
Run validation to check for errors before regenerating:
python generate_csv.py --validateThis will:
- Check all CCs 1-15 have definitions
- Verify no duplicate CC numbers
- Ensure all modes in
@modesare implemented - Compare generated CSV with existing to detect changes