MIT Mini Cheetah Made And Improved In China

October 19, 2019 by Gerrit Coetzee 21 Comments

We nearly passed over this tip from [xoxu] which was just a few links to some AliExpress pages. However, when we dug a bit into the pages we found something pretty surprising. Somewhere out there in the wild we…east of China there’s a company not only reverse engineering the Mini Cheetah, but improving it too.

We cover a lot of Mini Cheetah projects; it’s a small robot that can do a back-flip after all. When compared to the servo quadruped of not so many years ago it’s definitely exciting magic. Many of the projects go into detail about the control boards and motor modifications required to build a Mini Cheetah of your own. So we were especially interested to discover that this AliExpress seller has gone through the trouble of not just reverse engineering the design, but also improving on it. Claiming their motors are thinner and more dust resistant than what they’ve seen from MIT.

To be honest, we’re not sure what we’re looking at. It’s kind of cool that we live in a world where a video of a research project and some papers can turn into a $12k robot you can buy right now. Let us know what you think after the break.

Name A Hacker Camp

October 19, 2019 by Jenny List 31 Comments

Many of us look forward to visiting a summer hacker camp, as an opportunity to immerse ourselves in some of the coolest and most stimulating stuff that comes out of our community. The names trip off the tongue, ToorCamp, CCCamp, EMFcamp, BornHack, and more.

There’s one major event that doesn’t trip off the tongue in the same way though, because though it’s one of the oldest in our calendar it doesn’t have the same name every time. Since the end of the 1980s the Netherlands has seen a sequence of hacker camps with three letter names such as HAR, OHM, and SHA. Every four years these events delight and amaze us, and every four years they need a new name. Do you think you can help them pick one for 2021?

There are a few ground rules to observe, for the would-be coiner of a new moniker. The tradition is of a three-letter acronym, usually one with a meaning somewhere in technology, and so far always containing the letter H somewhere to stand for “Hack” in some form. The idea is that it should somehow encapsulate the spirit of hacker camp culture rather than simply be three words containing “Hack”. HAR for example was Hacking At Random, OHM was Observe Hack Make, and SHA was Still Hacking Anyway. So if you can dream up a TLA within those parameters, there is a group of hackers in the Netherlands who might like to hear from you. We suspect that HAD is already taken.

If you want to know more about the Netherlands camps, read our review of SHA, in 2017.

Header image: [Renze]. “Met Elkaar Hacken” means something close to “Hack together”.

Beam Me Up To The PCB Space Ship

October 19, 2019 by Sharon Lin 15 Comments

This project would fit in perfectly with #BadgeLife if someone could figure out a way to hang it from their neck. Inspired by Star Trek’s Starship Enterprise, [bobricius] decided to design and assemble a miniature space ship PCB model, complete with 40 blinking LEDs controlled by an ATtiny85.

While the design uses 0603, 0802, 3014, 4014, and 0805 LEDs, some substitutions can be made since the smallest LEDs can be difficult to solder. The light effects include a green laser, plasma coils, a deflector with scrolling blue LEDs, and the main plate and bridge for the space ship.

The LEDs are controlled by charlieplexing, a technique for driving LED arrays with relatively few I/O pins, different from traditional multiplexing. Charlieplexing allows n pins to drive n²−n LEDs, while traditional multiplexing allows n pins to drive (n/2)² LEDs. (Here is the best explanation of Charlieplexing we’ve ever seen.)

Especially with the compiled firmware running on the MCU, the PCB model makes for an impressive display.

The only catch? Your Starship Enterprise can’t actually fly.

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Customizing Xiaomi ARM Cortex-M Firmware

October 19, 2019 by Sharon Lin 2 Comments

This hack was revealed a while ago at DEFCON26, but it’s still a fascinating look into vulnerabilities that affect some of the most widely used IoT devices.

[Dennis Giese] figured out a way to modify ARM Cortex-M based firmware for use in customizing the functionality of devices or removing access to the vendor. Obviously, there are more malicious activities that can be done with this type of hack, as with any exploits of firmware, but they are (also) obviously not condoned.

The talk goes into the structure of Xiaomi ecosystem and products before going into a step-by-step approach to binary patching the firmware. The first step was to acquire the firmware, either by dumping SPI flash memory (using JTAG, SWD, or desoldered Flash pins) or intercepting traffic during a firmware update and downloading the firmware. There’s also a possibility of downloading the firmware using a URL, although this can be more difficult to find.

The firmware can then be parsed, which first requires the format to be converted from a proprietary format to and ELF file. This conversion makes it easier to load into IDA pro, and gives information on the segments of the firmware and its entry point. Python tools luckily exist for converting binary files to ELF, which simplifies the task.

After loading the ELF file into the disassembler, you’ll want to find the key memory area, denoted by “TAG_MAC”, “TAG_DID”, and “TAG_KEY” in the example firmware (for storing the MAC address, device ID, and key). In order to prepare the firmware for Nexmon – a software that supported C-based firmware binary patching for ARM Cortex-A and ARM Cortex-M binaries – you’ll need to partition some space in the memory for patches and know the function names and signatures for the firmware.

The latter is done by doing a difference comparison in the disassembler between an unknown executable and the example executable.

With the necessary information gathered, you can now use Nexmon to make your modifications. The fact that this can be done for smart devices at home means that smart devices you acquire – especially those partitioned by others – may contain malicious code, so take care when handling used devices.

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There’s More To The 3D Print Than The Eye Can See

October 19, 2019 by Sharon Lin 11 Comments

If you thought CADing designs for 3D printing was hard enough, wait until you hear about this .stl trick.

[Angus] of Maker’s Muse recently demoed a method for creating hidden geometries in .stl files that are only revealed during the slicing process before a 3D print. (Video, embedded below.) The process involves creating geometries with a thickness smaller than the size of the 3D printer’s nozzle that still appear to be solid in a .stl editor, but will not be rendered by a FDM slicer.

Most 3D printers have 0.4 mm thickness nozzle, so creating geometries with a wall thinner than this value will result in the effect that you’re looking for. Some possible uses for this trick are to create easter eggs or even to mess with other 3D printing enthusiasts. Of course, [Angus] recommends not to use this “deception for criminal or malicious intent” and I’d have to agree.

There’s a few other tricks that he reveals as well, including a way to create a body that’s actually a thin shell but appears to be solid: great for making unprintable letters that reveal hidden messages.

Nevertheless, it’s a cool trick and maybe one of those “features not bugs” in the slicer software.

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Converting A Tesla To A Pickup Truck

October 19, 2019 by Sharon Lin 38 Comments

The renowned inventor of useless robots [Simone Giertz] has outdone herself this time. She, along with a team of engineers featuring [Rich Rebuilds], [Laura Kampf], and [Marcos Ramirez], recently decided to convert a Tesla into a pickup truck, and make a video along the way, all while salvaging what remains they can of the back of the car and making the final product roadworthy. Yeah, this is a couple weeks old now, and yeah, it’s kind of a commercial, but really: [Simone Giertz] and Co. rock.

In her vlog of the experience, the team starts by gutting out the interior of the car in order to find out the weight distribution and form of the outer frame. Essentially, in order to create the pickup truck, a portion of the back of the car needs to be removed, with additional beams and support welded in depending on the consequent structural integrity. With a sawzall and angle grinder, the top portion of the frame is cut and taken out, but not before a worrying glance brings about the realization that the car needs exterior support during its modifications.

After the cushions, glass, wiring, and all other accessories are removed, they install a truck bed from another sacrificial pickup truck, as well as a roof rack to complete the look. Amidst the deconstruction and reconstruction, there are moments when the car encounters a “Safety restraint system fault” or when the team accidentally lines the inside of the car with fiberglass right before shooting their video. Between complaints of the different clip sizes used and the clear time pressure of the project, it’s a funny and informative look into a pretty unique car mod.

The final commercial they made of their Tesla-pickup hybrid, dubbed Truckla, is available on [Giertz]’s YouTube channel.

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