Moving Rainbow Challenge Card Ideas¶

Ideas for challenge cards built around the Moving Rainbow kit — a Raspberry Pi Pico wired to a NeoPixel LED strip and programmed in MicroPython (Chapter 19).

Beginning¶

Wire the Moving Rainbow Kit¶

Correctly wire the Pico's 5V, ground, and a chosen GPIO pin to the NeoPixel strip's power, ground, and data-in wire — making sure the data wire connects to the strip's DI end, not its DO end — then verify the wiring with the book's known-good three-line blink script. Stretch goal: identify what happens if the data wire is connected to the DO end instead.

Single Pixel Blink¶

Write a MicroPython script that turns exactly pixel 0 on to any color, waits, then turns it off, repeating in a loop — confirming the Pico and strip are communicating correctly before attempting any full-strip pattern. Stretch goal: blink pixel 0 and pixel 29 (the last pixel) at the same time, out of sync with each other.

Solid Color Fill¶

Light every pixel on the strip the same solid color using a loop that sets each index to the same RGB tuple, then change to a second solid color. Introduces addressing every pixel in the strip's indexed list at once. Stretch goal: cycle through three solid colors, each held for two seconds.

Traffic-Light Strip Sections¶

Light the first third of the strip red, the middle third yellow, and the last third green, all at the same time with no animation, introducing indexing a specific range of the pixel list rather than every pixel at once. Stretch goal: make the boundaries between sections adjustable by changing one variable.

Button-Controlled Color Toggle¶

Wire a push button so pressing it toggles the entire strip between two preset colors, combining the digital-input wiring skills from Beginning Circuits with NeoPixel output for the first time. Stretch goal: add a third color that cycles in after the first two.

Intermediate¶

Build the Moving Rainbow Pattern¶

Implement the book's own core pattern: set each pixel's color from (i + offset) % 255 inside the main loop, incrementing offset by one on every pass so the rainbow appears to travel down the strip. Stretch goal: make the rainbow travel in the opposite direction by changing how offset is applied.

Seasonal Pattern: Halloween Strobe¶

Build an orange-and-purple strobe pattern with an adjustable strobe-speed variable, matching the chapter's seasonal pattern gallery. Stretch goal: make the strobe speed controllable live with a potentiometer instead of a fixed variable.

Color Wheel Hue Cycle¶

Use the chapter's color-wheel/hue math to smoothly cycle the entire strip through the full rainbow of hues over time, where every pixel always matches and only the shared hue value changes — a deliberately different effect from the traveling Moving Rainbow pattern. Stretch goal: reverse the direction of the hue cycle partway through the animation.

Brightness Fade Breathing Effect¶

Smoothly ramp the strip's overall brightness up and down like a slow "breathing" light, gradually changing a brightness value over each pass through the loop instead of jumping straight between states. Stretch goal: combine breathing brightness with a fixed solid color of the student's choice.

Potentiometer-Controlled Speed¶

Wire a potentiometer as an analog input and use its live reading to control how quickly the Moving Rainbow pattern's offset increases, connecting a physical knob to animation speed in real time. Stretch goal: add a second potentiometer that controls overall brightness at the same time.

Advanced¶

Custom Seasonal Pattern Designer¶

Design and code an entirely new seasonal pattern not in the book's gallery — for a holiday or club event — documenting the chosen colors and the offset/timing formula used, then wire it in as a selectable option alongside the existing patterns. Stretch goal: get feedback from another student and revise the pattern based on it.

Multi-Pattern Mode Switcher¶

Wire a push button so each press advances the strip to the next pattern in a list of pattern functions (rainbow, strobe, breathing, solid), cycling through modes without ever re-uploading code. Stretch goal: add a long-press action that resets back to the first pattern.

Sound-Reactive Rainbow¶

Combine a sound sensor from the sound and IoT kits with the Moving Rainbow strip so the pattern's brightness or speed reacts to the ambient sound level, integrating a second sensor input directly into the animation loop. Often attempted with a partner given the two independent input/output systems involved. Stretch goal: make loud sounds trigger a completely different pattern rather than just brighter lights.

Two-Strip Synchronized Show¶

Wire and program two NeoPixel strips from a single Pico so both run synchronized or complementary patterns, such as mirrored rainbows traveling toward each other, managing two separate pixel-index loops inside one program. Stretch goal: make one strip's pattern depend on what the other strip is currently displaying.

Longer-Strip External Power Conversion¶

Following the chapter's guidance for strips beyond the stock kit size, plan and wire an external power supply for a longer strip — power and ground from the external supply, with data and a shared ground still running to the Pico — documenting in writing why the Pico's own 5V pin can no longer supply the strip safely. Stretch goal: calculate the maximum strip length the Pico's own 5V pin could safely power before this conversion becomes necessary.