Overview
Things
Story

Idea
Application Demonstration
Step 1: Hardware Layout
Step 2: Hacking the Micro:bit
Step 3: Solder the Lasers
Software: Ada Program
Area of Application
Future Works
Nightmare Warning: Laser Beam Alignment

Published February 16, 2019 © GPL3+

Laser Projector Badge

A laser projector made with 25 dot lasers, a micro:bit board, and Ada programming.

IntermediateFull instructions providedOver 1 day3,499

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Things used in this project

Hardware components

BBC micro:bit board

Dot Laser

PC817 Opto-Isolator

0 ohms Link

100

AWG Magnet wire

Generic Proto board 9x15 cm

Software apps and online services

AdaCore GNAT Community

Hand tools and fabrication machines

Soldering iron (generic)

Story

Idea

This project demonstrates a simple laser projector made with 25 dot laser diodes driven by a hacked micro:bit. It is a wearable device to project text messages on any flat surface.

Beam Alignment Testing with Smoke

As for the programming part, Ada is used to program the micro:bit board to generate text massage with the lasers. The Compiler/IDE used for the programming is GNAT Studio from AdaCore.

Application Demonstration

Hacked With Ada

It's mirrored

Step 1: Hardware Layout

25 Optocouplers are placed on a protoboard and soldered (+micro:bit).

1 / 2 • Optocoupler placement

Step 2: Hacking the Micro:bit

Onboard 25 LEDs are removed and polarity is identified as follows for wiring to the Optocouplers inputs. ( "-" to Cathode and "+" to Anode )

1 / 2 • 5x5 LEDs removed

A protoboard is added to breakout the I/O pins of micro:bit for future development.

1 / 2 • 2 PWM drive with MOSFET, SPI, I2C, ADC breakout and Battery power option

Step 3: Solder the Lasers

Original Idea was to use 25 Laser diodes but 20 Lasers (4 Columns) is enough to display and project scrolling text.

Laser diodes and 0 ohms link

After few episodes of painful soldering -

Laser Projector Badge

Software: Ada Program

Step 1: Installing GNAT Studio, Drivers and Examples

From this link : https://www.adacore.com/download, following two exe files are downloaded and installed on a Windows PC.

Download GNAT Studio and necessary stuffs

Step 2: Open Example Project

Run GPS (GNAT Programming Studio)

Opening an example project in GNAT

Open board specific example code from following location:

Starting with an existing example code for Microbit

Step 3: Modify Example Project

In the main.adb tab:

Change following code

with Display;
procedure Main is
begin
  loop
     Display.Scroll_Text ("Make with Ada! ");
  end loop;
end Main;

with

with Display;
procedure Main is
begin
  loop
     Display.Scroll_Text ("Hacked With Ada ");
  end loop;
end Main;

Step 4: Flash on Micro:bit

Flashing code to MicroBit

Area of Application

Advertisement during exhibition
LOS visual communication
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Future Works

Add BLE for uploading message
IoT Connectivity to nRF Cloud
Driving and sensing with unused I/O pins

Nightmare Warning: Laser Beam Alignment!

The hardest part of this project was to align the laser beams. It's literally a nightmare. Beware of that ! (Also, soldering 200+ joints was a huge pain)

Following "+" code can be used to align the beams against the center beam to adjust dot spacing and angular position.

I wish I didn't start this project!

Code

Untitled file

------------------------------------------------------------------------------
--                     Copyright (C) 2018, AdaCore                          --
--                                                                          --
-- This is free software;  you can redistribute it  and/or modify it  under --
-- terms of the  GNU General Public License as published  by the Free Soft- --
-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
-- sion.  This software is distributed in the hope  that it will be useful, --
-- but WITHOUT ANY WARRANTY;  without even the implied warranty of MERCHAN- --
-- TABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public --
-- License for  more details.  You should have  received  a copy of the GNU --
-- General  Public  License  distributed  with  this  software;   see  file --
-- COPYING3.  If not, go to http://www.gnu.org/licenses for a complete copy --
-- of the license.                                                          --
------------------------------------------------------------------------------

--  This simple example shows a scrolling text on the micro:bit LED matrix.
--
--  It is intended as first project to get familiar with Ada and GNAT
--  Programing Studio on the micro:bit.
--
--  For more advanced micro:bit features please have a look at the
--  Ada_Drivers_Library project: https://github.com/AdaCore/Ada_Drivers_Library
--
--  The micro:bit has a 5 x 5 multiplexed LED matrix, this means only one LED
--  can be lit at a time. To overcome this limitation, the LEDs are lit one
--  after the other very quickly. This process, called scanning, happens so fast
--  that the human eyes sees all the LED lit together (persistence of vision).
--  In this example, the scan is done with a periodic Timing_Event. Timing_Event
--  is an Ada standard feature that allows you to have a callback executed at a
--  give point in time and can be used to create periodic timers. The periodic
--  timers are implemented in the Generic_Timer package.
--
--  The LED matrix initialization and text scrolling are implemented in the
--  Display package.
--
--  The hardware maping for the GPIOs has been generated from a SVD description
--  file using SVD2Ada: https://github.com/AdaCore/svd2ada

with Display;

procedure Main is
begin

   loop
      Display.Scroll_Text ("Hacked with Ada ");
   end loop;
end Main;