2048 interactive pixels with Raspberry PI and Raspicam (project site)

##How to build the software This code runs on Raspbian. We use a model B second revision but it will probably run on any Pi. This code is based on a modified / stripped down version of raspivid. We found some very useful info on the website of Chris Cummings http://www.cheerfulprogrammer.com/downloads/camcv.c and Pierre Raufast http://raufast.org/download/camcv_vid0.c

###1) Download / clone Raspberry Pi userland code Create a folder src in your home dir and clone userland into this folder.

mkdir src
cd src
git clone https://github.com/raspberrypi/userland.git

###2) Download / clone this repo Now clone this code in your home dir.

cd
git clone https://github.com/fullscreennl/led-mirror.git

You now have this directory structure in your home dir:

.
├── src
|   └── userland
|
└── led-mirror
    ├── hardware
    └── software

NOTE: If you prefer a different folder layout change the paths in the makefile.

###3) Build The software is in led-mirror/software

cd led-mirror/software
sudo make 

You now have a ledmirror binary

###4) Run

sudo ./ledmirror

To start automatically on boot create an rc.local in /etc

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# Print the IP address
_IP=$(hostname -I) || true
if [ "$_IP" ]; then
  printf "My IP address is %s\n" "$_IP"
fi

sudo /home/pi/led-mirror/software/ledmirror

exit 0

##How to build the hardware

###Part List

###Power supply

• 5 Volt, 5 amp switching power supply, 1pcs
• Boxed enclosure, aluminium 15x25x10 cm, 1 pcs
• Universal mains power cable
• Euro style mains receiving connector

###PCBs

• PCBs were designed in Osmond PCB
• designs can be found here PCB designs

###Main board

• LED DRIVERS: MAX6960, 16 pcs
• 4 MHz crystal, running at 3.3 Volts, 1 pcs
• High speed line buffer, NC7SZ126M5 (used to buffer the clock signal), 16 pcs
• 24-pin header, (this will be a 26 pin boxed header in the future pcb version), 16 pcs
• 26-pin polarized boxed header, interfacing with the Pi, 1 pcs
• power header, polarized 2 pin connector, 1 pcs
• Voltage regulator, LM3940 3.3Volt Low Dropout Regulator, 4 pcs
• 33µF, 25volts tantalum capacitor, balancing LM3940, 4 pcs
• 470 nF, ceramic capacitor, balancing LM3940,4 pcs
• +/- 47µF 25 volts, to decouple the MAX6960's, 16 pcs
• 0.1 µF ceramic caps, for each MAX powersupply pin, 80 pcs

###LED boards

• LEDS, WHITE 10MM LEDS (FORWARD voltage < 3.3 Volts, use 8 per PCB), 2048 pcs
• Boxed Headers, 26 pin, 256 pieces
• Header 16 pins (2 on each PCB), 512 pcs
• Jumper in red color, 256 pcs

###Cables

• IDC female headers 26 pin, 256 (going to the LED panels)+ 16 (the main board end) + 2 (connecting the Pi to the main board)
• 26 wide ribbon cable, we used up and about 2.5 mters * 16 + 10 cm (Pi to Mainboard), roughly 40.5 meters
• 2 wire power cord, 5 meters

###Frame

• Metal tube, 6 cm diameter, 260 cm, 4 pcs
• Metal tube, 6 cm diameter, 200 cm, 10 pcs
• Tube couplings, Corner joint, 8 pcs
• Tube couplings, T joints, 4 pcs
• Grid panel, 244 X 122 cm, 3.8 cm pitched floor panel, 1 pcs

###How to assemble

Warning this is a massive soldering job. We started by soldering the LED panel PCBs. Headers first and LEDS (other side of PCB) second. After that you can partially implement the Main Board, testing one chip setup at a time.

fig 1.a Screenshot of Osmond showing the mainboard PCB design

fig 1.b Screenshot of Osmond showing the ledmodule PCB design

fig 2.0 PCBs (semi-)assembled

fig 3.0 Back of LED panel, all PCBs installed

####Jumper config

In order to keep the design of the LED panel pcb as uniform as possible, we decided to make them configurable through the use of jumpers. All led panel PCBs receive all 16 columns of data through the ribbon cable (and 8 rows of course), but the jumper decides which column is selected. Of cource this depends on the relative location of the LED-PCB in the subpanel (16 panels, 16 by 8 LEDS per MAX6960).

fig 4.0 Back of LED panel, jumper configuration detail

##Design decision

The following document shows how we configured our panel hardware/software wise. It is also a quick reference how the MAXes are addressed to show their relevant data in our chosen configuration/mode. All wrapping/manupulation of image data happens in software. Download as pdf here: LED-mirror_layout.pdf