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Using the PiCube on Raspberry Pi

23 February 2018

I recently had a chance to play with the PiCube, a 3D grid of 64 LEDs that you can control using the Raspberry Pi's 40 GPIO pins. It's a clever design based on multiplexing that makes this possible, but the compromise is that you can't individually control each light. All the layers that are switched on show the same lights. It's of limited use for games, then, but could be great for creating visual effects. If you're building a large robot, you could make its pulsing "heart" using PiCube (although not in a heart shape). I'm reminded of KITT's voice box in Knight Rider.

In education, it provides a highly visual way to explore nested loops and nested lists. It's also a good way to drill your soldering skills, since it comes in kit form.

You can read my review of it in issue 67 of The MagPi, which has just been published. It's available for free download, but you can support the Raspberry Pi Foundation by buying it, on the high street or by subscription.

Here's a video showing the PiCube in action:

And here's the code I wrote for that demo. PiCube comes with some demo programs, but the pin numbers were arranged in a linear list in them. I found it easier to work my way around the grid when I created a nested list for the pins, which I've called GRID_3D here.

#! /usr/bin/python import RPi.GPIO as GPIO import time GPIO.setwarnings(False) GPIO.setmode(GPIO.BOARD) LAYER = [40,38,36,32] GRID_3D = [[7, 11, 35, 37], [12, 13, 31, 33], [15, 16, 23, 29], [18, 19, 21, 22] ] def enable_layer(layer): GPIO.output(LAYER[layer], True) def disable_layer(layer): GPIO.output(LAYER[layer], False) def light_on(y, x, z): enable_layer(y) GPIO.output(GRID_3D[x][z], True) def light_off(y, x, z): enable_layer(y) GPIO.output(GRID_3D[x][z], False) def reset(): for x in range(4): for z in range(4): GPIO.output(GRID_3D[x][z], False) time.sleep(0.1) def resetlayer(): for i in range(0,4): GPIO.output(LAYER[i],False) for pin in LAYER: GPIO.setup(pin, GPIO.OUT) for x in range(4): for z in range(4): GPIO.setup(GRID_3D[x][z], GPIO.OUT) reset() resetlayer() # Display each light in turn for y in range(4): for x in range(4): for z in range(4): light_on(y, x, z) time.sleep(0.1) light_off(y, x, z) disable_layer(y) #Turn on all the lights for y in range(4): enable_layer(y) for x in range(4): for z in range(4): light_on(y, x, z) time.sleep(0.25)

PiCube is available now from SB Components.

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