Hologram Pi-ramid - Electronic Parts

I'm finally heading to the conclusion of this project which I have enjoyed beginning-to-end. Essentially this project will use a Raspberry Pi 3B+ and a Raspberry Pi Touch Display to work, but I've added as a bonus a few custom made PCBs and will add a Camera Module V2 to try making it more interesting.

The custom made PCBs have arrived which means is time to gather all the components needed and to start assembling the electronics!.

Electronics

BOM

• 1 x Raspberry Pi 3B+
• 1 x Raspberry Pi Touch Display
• 1 x Camera Module V2
• 4 x M3-0.50 x 4mm Socket Head Cap Screws (to secure the Touchscreen to 3D printed frame)
• 4 x #2 x 1/4" Slotted Round Head Screws (to secure the Camera to the 3D printed frame)
• 5 x WS2812B Addressable RGB LED
• 5 x 0.1µF, 6.3V Ceramic Capacitor, 0603[1608]

• 1 x 0.1" pitch (2.54 mm) Female Header: 1x4-Pin, Straight

• 1 x 0.1" pitch (2.54 mm) Male Header: 1x4-Pin, Straight

• Stranded Wire: Various colors, 26/28 AWG
• Heat-shrink tube

Custom made electronics prep work

Testing the WS2812B with Python

To make sure the WS2812B Addressable RGB LEDs work correctly (all of them) I wrote a simple Python sketch, that lights every LED with different colors for a fraction of a second, the LEDs should be connected as below picture which is how they will assembled into the project as well.

NeoPixel Library for Python

There are several libraries out there for controlling WS2812B LEDs with Python and a Raspberry Pi, perhaps the Neopixel is the easiest and the most popular library out there.

To install the Neopixel library I ran the following command:

sudo pip3 install rpi_ws281x adafruit-circuitpython-neopixel

Python RGB test code

When I was reviewing the :GAME ZIP 64 for the BBC micro:bit I remember I had this strange issue where a single RGB LED won't light blue -scenario which I accounted for; the script will turn on each RGB channel independently, then it will turn on the RGB channels in pairs and finally will do few random combinations (all RGB channels combined).

#!/usr/bin/env python3
# # -*- coding: utf-8 -*-


# Tests WS2812B Addressable LED with basic color pattern and some random RGB
#
# Luis Ortiz - luislab.com
# May 19, 2019


import board
import neopixel
import random
from time import sleep
import subprocess


numLEDs = 5


ledStrip = neopixel.NeoPixel(board.D18,
                             numLEDs,
                             brightness=0.01,
                             auto_write=True)


ledPos  = 0


seqNumber = 1
seqArray = [[0, 0, 0],
            [1, 0, 0],
            [0, 1, 0],
            [0, 0, 1],
            [0, 1, 1],
            [1, 0, 1],
            [1, 1, 0],
            [1, 1, 1]]


R = G = B = 0


try:
    while True:
        if (seqNumber < 8):
            R = seqArray[seqNumber][0]*255
            G = seqArray[seqNumber][1]*255
            B = seqArray[seqNumber][2]*255
        elif (seqNumber <= 13 and ledPos == 0):
            R = random.randint(0, 255)
            G = random.randint(0, 255)
            B = random.randint(0, 255)


        ledStrip[ledPos] = (R, G, B)


        ledPos = (ledPos + 1) % numLEDs


        if (ledPos == 0):
            seqNumber = (seqNumber + 1) % 14


        sleep(0.20)


except KeyboardInterrupt:
    ledStrip.fill((0, 0, 0))
    print("\nTest complete!")

After the testing is complete I continued with the assembly

Blogs in this series

1. Hologram Pi-ramid - Intro and initial design
2. Hologram Pi-ramid - 3D CAD/CAM design
3. Hologram Pi-ramid - 3D printed parts and initial assembly
4. Hologram Pi-ramid - Plexiglass Pyramid
5. Hologram Pi-ramid - My name is Automan
6. Hologram Pi-ramid - PCB Design
7. Hologram Pi-ramid - Painting the 3D printed parts
8. Hologram Pi-ramid - Electronic Parts
9. Hologram Pi-ramid - Displaying Holograms
10. Hologram Pi-ramid - Project complete!

• My Picasso Design Challenge entries