3D-Printed Tiger Lopes with the Help of a Motor

[Greg Zumwalt], master of 3D-printed mechanisms, has published his Saber 2 project as well as an assembly Instructable telling you how to put it together.

Saber 2 is a 3D-printed gear-and-cam saber-toothed tiger that can be motorized to show an excellent loping movement. It’s 14” long and 10” tall and consists of 108 components of which 34 are unique parts, and it all moves with the help of a 6 VDC 60 RPM gearmotor. With threaded PLA rods to keep it all together, and tapped holes to secure the rods, one imagines the printer would have to be pretty finely tuned and leveled for the parts to move as elegantly as you see in the video.

Hackaday readers might recall [Greg]’s 3D-printed projects such as his balloon-powered engine as well as his toy car also powered by balloons.

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Monoprice Select Mini Gets Smooth

We’ve had a love affair with the Monoprice Select Mini since it came out. The cheap printer has its flaws, though. One of them is that the controller is a bit opaque. On the one hand, it is impressive that it is a 32-bit board with an LCD. On the other hand, we have no way to modify it easily other than loading the ready-built binaries. Want to add bed leveling? Multiple fans? A second extruder and mixing head? Good luck, since the board doesn’t support any of those things. [mfink70] decided the controller had to go, so he upgraded his Mini with a Smoothie board.

On the plus side, the Smoothie board is also a 32-bit board with plenty of power and expansion capability. On the downside, it costs about half as much as the printer does. Just replacing the board was only part of the battle. [mfink70] had to worry about the steppers, the end stops, and a few other odds and ends.

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Precision Pressure In A Piston

[Scott] is building a DIY yeast reactor for his aquarium. What’s a yeast reactor? [Scott] wants to pump carbon dioxide into his aquarium so his aquatic plants grow more. He’s doing this with a gallon of sugary, yeasty water bubbling into a tank of plants and fish. In other words, [Scott] is doing this whole thing completely backward and utilizing the wrong waste product of the yeast metabolism.

However, along the way to pumping carbon dioxide into his aquarium, [Scott] created a very high precision pressure sensor. It’s based on a breakout board featuring the MS5611 air pressure sensor. This has a 24-bit ADC on board, which translates into one ten-thousandths of a pound per square inch of pressure.

To integrate this pressure sensor into the aquarium/unbrewery setup, [Scott] created a pressure meter out of a syringe. With the plunger end of this syringe encased in epoxy and the pointy end still able to accept needles, [Scott] is able to easily plug this sensor into his yeast reactor. The data from the sensor is accessible over I2C, and a simple circuit with an ATmega328 and a character LCD displays the current pressure in the syringe.

We’ve seen these high-resolution pressure sensors used in drones and rockets as altimeters before, but never as a pressure gauge. This, though, is a cheap and novel solution for measuring pressures between a vacuum and a bit over one atmosphere.

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Keep the Burglars Away With Some Pi

Ten years ago, we never imagined we would be able to ward off burglars with Pi. However, that is exactly what [Nick] is doing with his Raspberry Pi home security system.

We like how, instead of using a standard siren, [Nick] utilized his existing stereo system to play a custom audio file that he created. (Oh the possibilities!) How many off the shelf alarm systems can you do that with?

The Pi is the brains of the operation, running an open source software program called Home Assistant. If any of the Z-Wave sensors in his house are triggered while the alarm system is armed, the system begins taking several actions. The stereo system is turned on via IR so that the digital alarm audio file can be played. Lights flash on and off. An IP camera takes several snapshots and emails them to [Nick].

Home Assistant didn’t actually have the ability to send images in an email inline at the time that [Nick] was putting together his system. What did [Nick] do about that? He wrote some code to give it that ability, and submitted it through GitHub. That new code was put into a later version of the program. Ah, the beauty of open source software.

Perhaps the most important part of this project is that there were steps taken to help keep the wife-approval factor of the system on the positive side. For example, he configured one of the scripts so that even if the alarm is tripped multiple times in succession, the alarm won’t play over itself repeatedly.

This isn’t [Nick’s] first time being featured here. Check out another project of his which involves a couple of Pi’s communicating with each other via lasers.


Hackaday Prize Entry: Coaxial Drones

[Glytch] has been building drones since before they were called drones. Instead of submitting his time machine into the Hackaday Prize, he’s throwing his pocket sized, 3D printable coaxial drone into the ring.

His focus is on designing small and very portable drones, preferably one that has folding arms and can fit into a backpack. His portfolio even includes a clone of the DJI Mavic, the gimbaled camera-carrying consumer drone known for its small volume when folded.

Navi — [Glitch]’s entry for the Hackaday Prize — is a complete departure from quadcopters with folding arms. It’s simple to use, and all he needs to do to launch it is hold it in the air and press a button. It does this by being a coaxial drone, or a cylinder with a pair of folding props sticking out the side. The chassis and mechanics for this drone are 3D printable, making this an awesome entry for the Hackaday Prize.

Building an OBD Speed Pulse: Behold the ICE

I am a crappy software coder when it comes down to it. I didn’t pay attention when everything went object oriented and my roots were always assembly language and Real Time Operating Systems (RTOS) anyways.

So it only natural that I would reach for a true In-Circuit-Emulator (ICE) to finish of my little OBDII bus to speed pulse generator widget. ICE is a hardware device used to debug embedded systems. It communicates with the microcontroller on your board, allowing you to view what is going on by pausing execution and inspecting or changing values in the hardware registers. If you want to be great at embedded development you need to be great at using in-circuit emulation.

Not only do I get to watch my mistakes in near real time, I get to make a video about it.

Getting Data Out of a Vehicle

I’ve been working on a small board which will plug into my car and give direct access to speed reported on the Controller Area Network (CAN bus).

To back up a bit, my last video post was about my inane desire to make a small assembly that could plug into the OBDII port on my truck and create a series of pulses representing the speed of the vehicle for my GPS to function much more accurately. While there was a wire buried deep in the multiple bundles of wires connected to the vehicle’s Engine Control Module, I have decided for numerous reasons to create my own signal source.

At the heart of my project is the need to convert the OBDII port and the underlying CAN protocol to a simple variable representing the speed, and to then covert that value to a pulse stream where the frequency varied based on speed. The OBDII/CAN Protocol is handled by the STN1110 chip and converted to ASCII, and I am using an ATmega328 like found on a multitude of Arduino’ish boards for the ASCII to pulse conversion. I’m using hardware interrupts to control the signal output for rock-solid, jitter-free timing.

Walk through the process of using an In-Circuit Emulator in the video below, and join me after the break for a few more details on the process.

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A Full Stack GPS Receiver

The usual way of adding GPS capabilities to a project is grabbing an off-the-shelf GPS module, plugging it into a UART, and reading the stream of NMEA sentences coming out of a serial port. Depending on how much you spend on a GPS module, this is fine: the best modules out there start up quickly, and a lot of them recognize the logical AND in ITAR regulations.

For [Mike], grabbing an off-the-shelf module is out of the question. He’s building his own GPS receiver from the ground up using a bit of hardware and FPGA hacking. Already he’s getting good results, and he doesn’t have to futz around with those messy, ‘don’t build ballistic missiles’ laws.

The hardware for this build includes a Kiwi SDR ‘cape’ for the BeagleBone and a Digilent Nexus-2 FPGA board. The SDR board captures raw 1-bit samples taken at 16.268 MHz, and requires a full minute’s worth of data to be captured. That’s at least 120 Megabytes of data for the FPGA to sort through.

The software for this project first acquires the GPS signal by finding the approximate frequency and phase. The software then locks on to the carrier, figures out the phase, and receives the 50bps ‘NAV’ message that’s required to find a position solution for the antenna’s location. The first version of this software was exceptionally slow, taking over 6 hours to process 200 seconds of data. Now, [Mike] has improved the channel tracking code and made it 300 times faster. That’s real-time processing of GPS data, using commodity off-the-shelf hardware. All the software is available on the Gits, making this a project that can very easily be replicated by anyone. We would expect the US State Department or DOD to pay [Mike] a visit shortly.

Of course, this isn’t the first time someone has built a GPS receiver from scratch. A few years ago, less than 1-meter accuracy was possible with an FPGA and a homebrew RF board.