BrickEngineer: LEGO Design

LEGO Engineering for LEGO NXT and Robot Enthusiasts

Tag Archives: microcontrollers

Raspberry Pi: An ARM GNU/Linux box for $25


Move over LEGO brick!
Here comes Raspberry Pi, and it is going to change the face of robotics forever!

Raspberry Pi is Linux machine the size of a credit card. Plug in your television and a keyboard and you have a fully-functional computer for $25.
YES!!!
TWENTY-FIVE DOLLARS!!!!

Layout of the Raspberry Pi ARM GNU/Linux Box Computer

Models:
There are two models, Model A and Model B.
Model A has 256MB RAM, 1 USB port and no Ethernet (network connection).
Model B has 256MB RAM, 2 USB ports and an Ethernet port.

Specs:
It relies on a System on a Chip (SoC). The particular SoC used is Broadcom BCM2835. The Broadcom BNC2835 is a High Definition 1080p Embedded Multimedia Applications Processor. It relies on the ARM1176 (ARM1176JZF-S) Processor which has a floating point processor and runs at 700 MHz. Moreover, the SoC has a Videocore 4 GPU, which is capable of BluRay quality playback, using H.264 at 40MBits/s. The Broadcom BNC2835 has a fast 3D core accessed using the supplied OpenGL ES2.0 and OpenVG libraries. The GPU is capable of 1 Gpixel/s, 1.5 Gtexel/s or 24 GFLOPs of general purpose computing.

Size:
The Raspberry Pi is SMALL!
The card is slightly larger than 85.60 mm x 53.98 mm x 17 mm due to the fact that the SD card and connectors project over the edges. It weighs with a mass of 45g. The Raspberry Pi is low power and runs on 4 AA cells.

Programming:
Fedora, Debian and ArchLinux are supported and other distributions will be supported later. Python is the official educational language.

I cant wait to get my hands on one of these and begin interfacing directly with the LEGO motors and sensors!

A photograph of the Raspberry Pi

DIY Arduino Circuit

Jameco.com has an interesting article on how to build your own Arduino microcontroller circuit.

Image of a circuit board

The circuit relies on an ATMega328 microcontroller, and since it requires only component parts it is cheaper and has a potentially smaller footprint than the popular Arduino Boards.

We have started using Arduino microcontrollers to directly control the LEGO Motors (9842), and expect to post on this sometime in the near future. In the meantime check out posts on LEGO NXT motor control:

LEGO NXT Motor Wiring
Hacking the LEGO Mindstorms NXT Standard Motor

Infrared-Ultrasonic Beacons for Localization

An article at NXTasy.org highlights a three-wheeled robot that moves in one dimension and detects signals from an external beacon that emits ultrasonic bursts.  The robot relies on a microcontroller that runs a Kalman filter to perform and maintain spatial localization.  The NXT software is implemented using the LabVIEW NXT toolkit

NXT Reciever with Kalman Filter

NXT Reciever with Kalman Filter

Details on the project can be found at http://www.convict.lu/htm/rob/ir_us.htm#Kalman

Basic Electronics Supplies for Beginners

I am getting interested in more general robotics projects, but will still be relying on LEGOs for their construction.  The LEGO brick is a bit too limited with its specialized programming languages and limited sensor and motor ports.

So for those interested in some LEGO electronics hacking, here is a list of supplies that will get you up and running fast for about $275… just a but more than the cost of a single Mindstorms kit.  Plus you’ll now get to learn electronics!

First, check out the book:
Making Things Talk: Practical Methods for Connecting Physical Objects

This book explains how to wire, program and interconnect various microcontrollers, some of which are very closely related to those used by the NXT Brick.

Supply List

Item Number Description Quantity Unit Price Total
Amazon.com
  Making Things Talk 1  $19.79 $19.79
Jameco.com
19166 Desoldering Pump 1 $4.95 $4.95
159291 Wire Stripper 1 $10.15 $10.15
161411 Diagonal Cutter 1 $7.49 $7.49
35474 Needlenose Pliers 1 $5.49 $5.49
127271 Mini Screwdriver 1 $1.89 $1.89
681002 Helping Hands 1 $8.75 $8.75
159611 Power Connector 2 $1.79 $3.58
10444 Alligator Test Clip Leads 2 $4.39 $8.78
103377 Header Pins 10 $0.16 $1.60
119011 Push Button (PCB Type) 10 $0.27 $2.70
29082 Potentiometer 2 $1.05 $2.10
242115 LM1117T-3.3 Voltage Regulator 3 $1.39 $4.17
51262 7805T 5v Voltage regulator 3 $0.32 $0.96
38236 2N2222A Transistor NPN 5 $0.41 $2.05
32993 TIP120 Power Transistor 5 $0.45 $2.25
643488 3.3V Zener Diode 5 $0.03 $0.16
35991 1N4004 Diode 5 $0.04 $0.20
152792 LED Yellow 10 $0.17 $1.70
152805 LED Red 10 $0.21 $2.10
153139 LED Orange 10 $0.35 $3.50
156962 LED Green (567 nm) 10 $0.20 $2.00
334529 LED Bargraph Red 1 $1.31 $1.31
334537 LED Bargraph Yellow 1 $1.23 $1.23
334511 LED Bargraph Green 1 $1.28 $1.28
17187 7-segment LED Display 3 $0.88 $2.64
38818 4-switch DIP 4 $0.48 $1.92
38842 8-switch DIP 2 $0.89 $1.78
103166 Resistor Refill 1 $12.95 $12.95
15270 0.1 uF 10 $0.15 $1.53
94161 1 uF 10 $0.12 $1.20
29891 10 uF 10 $0.06 $0.60
158394 100 uF 10 $0.11 $1.08
MPJA
4443 TE Solderless Breadboard 1 $4.95 $4.95
4447 TE Large Solderless Breadboard 1 $22.95 $22.95
7027 TE Jumpers 2 $3.95 $7.90
14213 TE Digital Multimeter 1 $14.95 $14.95
15860 TL Mini Soldering Station 1 $14.95 $14.95
Sparkfun
Wiring Platform DEV-00744 1 $84.95 $84.95
Radio Shack
64-025 Lead Free Solder 1 $3.89 $3.89

Note that the light gray items are optional, and not necessary.

Also, this list does not include some sort of power supply. Pulling one out of an old computer is an easy option. Or rechargeable batteries work well too (in which case you will need battery holders).

Last, there are special items in the book Making Things Talk that you may decide to purchase separately, such as flex sensors, or bluetooth boards, etc.

You can store your electronics in much the same way you store your small LEGO parts. Check out the article on Storage.

Enjoy Hacking!

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