Python And Pi Provide Heads Up Display For Your Experimental Airplane

May 10, 2019 by Brian Benchoff 9 Comments

You shouldn’t be looking at screens when you’re driving, but what about a heads-up display? A screen that could put relevant information in your field of vision would be great, even more so if it used a Raspberry Pi. That’s exactly what [John] did, only he did it with an airplane.

First up, the legality of this build. [John]’s plane is registered as experimental, which, provided you know what you’re doing, is pretty close to ‘anything goes’ as you would want in a manned aircraft. [John] has a sufficient number of hours in his log book, and he’s built a Zenith 701.

For hardware, the hard part of this build is constructing a heads-up display. Fortunately, aftermarket HUDs exist, and [John] is using a Kivic projector, a $200 piece of equipment that’s readily available on Amazon. If you need a HUD for your car, there you go. The software is another thing entirely, with the goal of having the software decoupled from the display and data sources. This is somewhat easy to accomplish with a Raspberry Pi; the display is actually just some minimal text-based blocky graphics built in PyGame. This build is also decoupled from the data sources by building this as a user interface for Stratux, an independent Raspberry Pi-based ADS-B receiver for pilots.

There are several views available with this HUD, with the AHRS + ADS-B providing information on the aircraft’s attitude and altitude, along with a few indicators of the nearest planes. The traffic view expands on the ADS-B data, showing the nearest eight or so aircraft in the air, with a range, bearing, and difference in altitude. There’s a diagnostic window, and since [John]’s plane is a backcountry STOL thingamado that can hover in a strong wind, there’s also a digital version of a norden bombsight. It’s for dropping bags of flour onto a grass strip. You can check out [John]’s entire AirVenture presentation of the build below, with all the code available here.

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Barn Door Tracker Needs No Special Tools

May 10, 2019 by Adam Fabio 15 Comments

If you want to take a long exposure photograph, you need a tripod to hold your camera steady. But a tripod won’t help when the ground it’s standing on is moving. That’s exactly the problem [Emvilza] ran into when he wanted to take minutes or hours long photographs of the night sky. His solution was to build a barn door tracker, which he carefully documented in both English and Spanish.

Barn door trackers, also known as scotch mounts have been used by photographers for many years to cancel out the rotation of the earth. This causes stars to appear frozen in the sky and allows for photographs of very dim celestial objects. These trackers range from simple hand-cranked affairs to complex mechanical creations. [Emvilza] decided to have a go at designing and building his own tracker, using only basic tools, as he didn’t have access to a CNC or 3D printer.

The tracker itself is built from wood, with metal hardware. [Emvilza] spent a ton of time designing the tracker using SketchUp. The carefully drawn plans ensured everything would fit together and operate correctly.

One of the toughest parts was accurately bending a threaded rod enough to make it work with the tracker, but not bind the drive system. The mount’s motion comes from a threaded rod. The rod is driven by a stepper motor. Control and sensing is handled by an ATmega328 programmed using the Arduino toolchain. [Emvilza] learned Eagle and designed a PCB. Rather than etch a board, he simply built the circuit on perfboard, following his layout and traces.

The end result is a tracker that looks and performs great — just check out the images on [Emvilza’s] site to see some examples. Not only that, [Emvilza’s] well written documentation will help anyone looking to build a tracker in the future!

Old Nixie Display Rides Again As 3D-Printer Filament Meter

May 9, 2019 by Dan Maloney 9 Comments

We’re not sure about the name of this Nixie tube filament meter that [Scott M. Baker] built. He calls it a “filadometer”, perhaps a portmanteau of “filament” and “odometer”, in which case it makes sense. It may not flow trippingly from the tongue and we can’t come up with anything better, but whatever moniker you use it’s actually a pretty cool build.

The filadometer started life as something completely different and utterly typical for Nixie tube projects – a temperature and humidity gauge. [Scott] decided to recycle the eight-tube display to keep track of his Prusa, and in doing so he reveals a pretty remarkable degree of forethought in his design process. The original Nixie display has all the usual trappings – the driver chips, the shift registers, and the high voltage power supply. What stands out is the modularity of his design: the tube sockets and drivers live on a backplane PCB, with a Raspberry Pi and a separate HV supply board plugging into it. The original display had a Model B Pi, so there was plenty of room for a new Zero W. A new printed case and a little programming to capture the filament use from Octoprint is all it took to put this nifty little build back in action. The video below shows the details.

We’re always excited to see new videos from [Scott] because we learn so much from looking over his virtual shoulder. If you haven’t checked out his stuff, take a look at his homage to the 8″ floppy or his dual-port memory hack for retro gaming.

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Stator Library Makes Your Arduino Code Easier To Read

May 9, 2019 by Lewin Day 56 Comments

The readability of your code can make the difference between your project being a joy to work on, or an absolute headache. This goes double when collaborating with others. Having easily parsed code reduces your cognitive load and makes solving problems easier. To try and help with this, [PTS93] developed the Stator library to make certain common tasks simpler to read.

The aim of the library is to get rid of piles of state tracking variables and endless if/else statements – hence the name. It’s designed primarily for the Arduino IDE but doesn’t have any dependencies on the API, so can be used in other C++ environments. It comes with a variety of neat tools for common jobs, such as reading an analog sensor with hysteresis around a trigger point, as well as easy ways to track state changes across multiple variables. By using basic English terms instead of condition checks and mathematical operators, it can make things more readable and easier to follow.

The power of the Arduino platform has always been in its easy to use libraries that make everything easier, from interfacing LCDs to working with Amazon Dash buttons.

CPU Made From 74HC Chips Is A Glorious Mess

May 9, 2019 by Inderpreet Singh 35 Comments

Did you ever start a project that you felt gained a life of its own? This project by [Paulo Constantino] is an entire CPU named dreamcatcher on breadboards, and is a beautiful jungle of digital. On top of that, it works to connect to an analog VGA display. How cool is that!

Designing an ALU and then a CPU is a typical exercise for students of digital design and is done using VerilogHDL or VHDL. It involves creating an ALU that can add, subtract etc while a control unit manages data moves and the like. There is also a memory fetch and instruction decode made up of de-mulitiplexers and a bunch of flip-flops that make up registers and flags. They are as complex as they sound if not more.

[Paulo Constantino] went ahead and designed the whole thing in Eagle as a schematic using 74HC logic chips. To build it though instead of a PCB he used breadboards. Everything from bus decoders to controlling an external VGA display is done using jumper wires. We did cover a video on the project a while back, but this update adds a video card interface to the build.

The CPU updates the display buffer on the VGA card, and in the video below shows the slow and steady update. The fact that the jungle of wires can drive a display is awesome. He has since started working on a 16-bit version of the processor and we’d love to see someone take it up a notch.

For those more accustomed to the PCB, the Z80 membership card project is a great build for 8-bit computer fans.

Thanks to [analog engineer] for the tip.

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Sniffing CAN To Add New Features To A Modern Car

May 9, 2019 by Tom Nardi 40 Comments

It used to be that there wasn’t a problem on the average car that couldn’t be solved with a nice set of wrenches, a case of beer, and a long weekend. But the modern automobile has more in common with a spaceship than those vintage rides of yesteryear. Bristling with sensors and electronics, we’re at the point that some high-end cars need to go back to the dealer for even minor repairs. It’s a dark time for the neighborhood grease monkey.

But for those of us who are more likely to spend their free time working with a compiler than a carburetor, a modern car can be an absolute wonderland. That’s what [TJ Bruno] found when he recently started experimenting with the CAN bus on his 2017 Chevy Cruze. Not only was he able to decode how the different switches and buttons on the dashboard communicated with the vehicle’s onboard systems, he was able to hack in a forward-looking camera that’s so well integrated you’d swear it was a factory option.

The idea started simple enough: using some relays, [TJ] planned on physically switching the video feed going to the Chevy’s dashboard between the stock rear camera and his aftermarket front camera. That’s all well and good, but the car would still only bring up the video feed when the gear selector was put in reverse; not exactly helpful when he’s trying to inch his way into a tight spot. He needed to find a way to bring up the video display when the car was moving forward.

With a PCAN-USB adapter connected to the car’s OBD-II port, he shifted into and out of reverse a few times and noted which messages got transmitted on the network. It wasn’t long before he isolated the proper message, and when he injected it with his laptop, the dashboard display switched over to the backup camera regardless of what gear the car was in. Building on this success, he eventually figured out how to read the status of all the buttons on the car’s dashboard, and programmed an Arduino to listen for the appropriate signals.

The final piece of the puzzle was combing bringing both of these capabilities, so that went the appropriate button was pressed on the dashboard the Arduino would not only send the signal to turn on the video display, but kick the relays over to switch the camera source. Now [TJ] has a front-facing camera that can be called up without having to kludge together some button or switch that would never match the modern styling of the vehicle’s interior.

A couple years back we saw a similar project to add a backup camera to a Peugeot 207 that was too old to have one from the factory, and more recently we saw how CAN hacking can allow you to fight back when your car’s touch screen interface robs you of simple pleasures like pushing buttons and turning knobs.

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The Two-Dimensional Stepper Motor

May 9, 2019 by Brian Benchoff 20 Comments

Over on hackaday.io and deep in the Hackaday Prize, a lot of cool people are playing around with the possibilities of putting coils in printed circuit boards. On the face of it, it makes sense: drawing spirals on a PCB gets you an electromagnet. This allows you to do all sorts of crazy things. You can make miniature model maglev trains using the track as a motor. Someone built a wearable Tesla coil.

The latest build to show off the possibilities of motors etched on PCBs is [bobricius]’ micro manipulator. It’s a 100 mm square board capable of moving a small magnet around the surface. The point? Well, if you have to ask that question you’re really never going to get the point.

The design of this stepper motor is simply two coils of wire, with the X axis of the grid placed on the top copper layer of the PCB and the Y axis on the bottom copper layer. There are four poles to each of these coils, and they plug right into a standard stepper driver, so to control this board all you need is a basic Arduino and a motor shield. Or a RepRap board, take your pick, you probably have something sitting around in a junk drawer.

In the test of this board, the stepper motor can move small rare earth magnets around quickly and with high repeatability. As for what use this PCB stepper motor has, if you have to ask that question, you’ll never know. Also, because it looks cool.