Neopixel Blaster

The Synthiam NeoPixel Blaster is a small DIY (do-it-yourself) controller board that makes it easy for your robot to drive a lot of NeoPixels (addressable RGB LEDs such as WS2812/WS2812B). It can control up to 640 pixels total using 8 separate output ports (that’s up to 80 pixels per port).

After you add this skill to your ARC project, you will send it commands using ControlCommand(). You typically follow this pattern:

1. DefineSize: tell ARC how many pixels exist on a port
2. Set / SetAll: choose colors for one pixel or all pixels
3. Update: push the changes to the LEDs (nothing changes until you call Update)

Hardware (DIY)

Reference page: Roll Out - Neo Pixel Blaster
Design files on GitHub: https://github.com/synthiam/E-21_Neopixel_Blaster

Ports and pixel limits

• 8 output ports: numbered 0 through 7
• 80 pixels per port (maximum)
• 640 pixels total across all ports (8 × 80)

Special note about Port 0 (onboard NeoPixel)

Port 0 includes an onboard RGB LED on the NeoPixel Blaster itself. That onboard LED is part of the NeoPixel chain for Port 0 and it uses the first pixel address.

Basic setup checklist (beginner-friendly)

• Connect the NeoPixel Blaster to your robot controller (the robot controller will communicate with the Blaster, and the Blaster drives the LEDs). In ARC, you will choose the digital port used for that connection.
• Connect NeoPixels to the desired Blaster output port (0–7). Keep track of which LED strip/ring is connected to which port number.
• Power considerations: NeoPixels can draw significant current, especially at bright white. Use an appropriate power supply for your LED count and wiring (common NeoPixel best-practice).

Using the skill in ARC

Once the NeoPixel Blaster skill is added to your ARC project, you control it from scripts using: ControlCommand("NeoPixel", ...)

Command concepts (plain English)

Examples (EZ-Script / C# style snippets)

Example 1: Set the onboard LED (Port 0, Pixel 0) to purple

This defines 1 pixel on Port 0 (the onboard LED) and sets it to purple using RGB values.

ControlCommand("NeoPixel", DefineSize, 0, 1)

ControlCommand("NeoPixel", SetAll, 0, 255, 0, 255)

ControlCommand("NeoPixel", Update, 0)

Example 2: Port 0 with 3 pixels total (onboard + 2 external)

This example assumes 3 pixels are on Port 0: Pixel 0 is the onboard LED, and Pixels 1–2 are on your connected strip. Each pixel is set to a different color.

ControlCommand("NeoPixel", DefineSize, 0, 3)

ControlCommand("NeoPixel", Set, 0, 0, 0, 0, 255) # blue onboard LED

ControlCommand("NeoPixel", Set, 0, 1, 0, 255, 0) # green second LED

ControlCommand("NeoPixel", Set, 0, 2, 255, 0, 0) # red third LED

ControlCommand("NeoPixel", Update, 0)

Example 3: Scrolling color pattern (Port 1, 64 pixels)

This creates a simple animation by shifting an $offset value each loop. It targets Port 1, where Pixel 0 is the first LED on your strip (no onboard pixel on Port 1).

ControlCommand("NeoPixel", DefineSize, 1, 64)

$offset = 0

:loop

repeat ($x, 0, 63, 1)
  ControlCommand("NeoPixel", Set, 1, ($x + $offset) % 64, (64 - $x) % 12, $x / 2, $x % 38)
endrepeat

ControlCommand("NeoPixel", Update, 1)

sleep(100)

$offset++

goto(loop)

Example 4: “Matrix” style green trail (Port 1, 64 pixels)

This keeps red and green low and varies blue slightly to create a dim trailing effect. Reduce or increase the sleep(10) value to slow down or speed up the animation.

ControlCommand("NeoPixel", DefineSize, 1, 64)

$offset = 0

:loop

repeat ($x, 0, 63, 1)
  ControlCommand("NeoPixel", Set, 1, ($x + $offset) % 64, 0, 0, (64 - $x) % 20)
endrepeat

ControlCommand("NeoPixel", Update, 1)

sleep(10)

$offset++

goto(loop)

Example 5: Sparkle Matrix (adds random sparkles)

This starts with the same trailing effect as Example 4, then picks a random pixel and assigns it a random RGB color to create “sparkles.”

ControlCommand("NeoPixel", DefineSize, 1, 64)

$offset = 0

:loop

repeat ($x, 0, 63, 1)
  ControlCommand("NeoPixel", Set, 1, ($x + $offset) % 64, 0, 0, (64 - $x) % 20)
#  ControlCommand("NeoPixel", Set, 1, ($x + $offset) % 64, (64 - $x) % 12, $x / 2, $x % 38)
endrepeat

  $i = getrandom(0, 63)  
  $r = getrandom(0, 53)
  $g = getrandom(0, 53)
  $b = getrandom(0, 53)
  
  ControlCommand("NeoPixel", Set, 1, $i, $r, $g, $b)

ControlCommand("NeoPixel", Update, 1)

sleep(10)

$offset++

goto(loop)

Troubleshooting (common beginner issues)

For additional commands and parameters, refer to the skill’s Cheat Sheet inside ARC.