Having recently purchased a Hobie 14-ft catamaran, I have been having fun out on the water, but also wondering how fast I’ve been going. To give myself some idea, I decided to make my own instruments using an Arduino, LCD and GPS.
My first prototype is shown, displaying the speed in knots (0.0), the current compass heading (111°), the time, number of satellites (07), and the battery voltage (412mV). If you add on an OpenLog from Sparkfun, you can save all the GPS data to a flash card for viewing on a computer later. Best of all, it’s really quite easy to make! Continue reading
Over the past few years, the back of my mind has been thinking about a small, quick, camera robot I could drive around. Recently, with the help of a 3D printer I was finally able to print a chassis and put one together quickly. Continue reading
I decided to try my hand at designing and 3D printing a phone holder using Solidworks. Two prongs on the back allow me to attach it to a car’s AC vent, and the thread on one side allows it to be mounted on a tripod. Designing it myself allows the phone and case to fit snugly.
I printed it out in ABS plastic at the Techshop in about 3 hours. The phone fits pretty well, but it’s a little loose. In the next iteration I can tighten up the tolerances.
A while back I bought some cheap, multi-colour LED modules on ebay. I’m not sure what they were designed to be used for, as each time power was applied they cycled through different colour combinations. The modules had an AT89C2051 microcontroller on the back which would be too bothersome to reprogram, so I decided to do a bit of reverse engineering and control each module externally.
My idea was to create a MIDI controlled array out of the modules, to visualise the notes coming from a piano keyboard. To do this I removed the microcontroller on each module and mapped the circuit layout to find the control lines for each group of LEDs. I decided to build an array of 3 x 4 modules, 12 in total to match the number of semitones in a (western) musical octave. So 12 modules * 3 colours per module = 36 outputs to control. To control this many I ordered some free samples of the TLC5940 from Texas Instruments, which is a 16-Channel PWM LED Driver. With three of these chips I could control up to 48 outputs, more than enough!
For the brains I ordered a ATMEGA 32U4 board from Sparkfun. The nice thing about these boards is that they come with a USB connected bootloader, making them super easy to program with AVRDUDE. The only trick was using the board’s ISP header to reprogram the fuse settings.
To drive the TLC5940 chips, I found an excellent C library and notes written by Matthew Pandina. I then needed to build a MIDI input circuit and connected it to the ATMega32’s UART RX pin. There is a great article on interfacing MIDI signals to and AVR on avrfreaks.net. Next came writing code to put it all together and map MIDI notes to particular LEDs.
The initial source code I’ve written is available here. There are still some bugs so use it at your own risk! Here it is in action:
Being inspired by these AMAZING DESIGNS by Wanda Sowry, I decided to design my own automaton with a sailing theme. My first version was a failure. It was overly complicated and had too many gears. So I wrote it off as a learning experience and started afresh.
After a few rough sketches of what I wanted, I used Solidworks to create the design and model each part. I could then define how the parts moved and interacted with each other, to refine the design and make sure it would work. It was then a matter of exporting each piece to Corel Draw so they could be cut on the laser cutter at my local Techshop.
The fun part is painting, assembling and gluing all the pieces together. I made plenty of notes too on how the design could be improved and what tolerances work best. With everything assembled and working, I just need to show it off!
BEWARE THE GIANT SQUID!
Thought I’d see what this 3D printing thing is all about. Turns out it couldn’t be easier! You choose a part from Thingiverse, such as a Gear Heart, download the model, load it into Makerware and just press print! I printed it on the Makerbot Replicator 2X at Techshop Pittsburgh, and it took about 9 hours. I’m impressed with how sturdy it is and how well the gears mesh.
Time to design my own models!
Poking around on the internet one day, I found this clever Cat and Mouse Automata from Germany, and decided to try and build it. The plans are available free for download too!
I think it’s cheating to use a laser cutter for this sort of project, but it lets you build it fast and accurately. Within an hour of changing parts of the design to US units (sigh) to match my materials and ten minutes of cutting, I had all the parts ready. Assembly took several days as I glued a few parts at a time.
I’m now inspired to design and build my own automata projects, so stay tuned!