The game of Chinese Whispers or Telephone involves telling one person a sentence, having that person tell another person the same sentence, and continuing on until purple monkey dishwasher. For this year’s Arduino Day, [Mastro] was hanging out at Crunchlab with a bunch of Arduinos. What do you do with a bunch of Arduinos? Telephone with software serial.
The setup for this game is extremely simple – have one Arduino act as the master, listening for bits on the (hardware) serial port. This Arduino then sends those bits down a chain of Arduinos over the software serial port until it finally loops around to the master. The result is displayed in a terminal.
With only about a dozen Arduinos in this game of Telephone, [Mastro] did get a few transmission errors. That’s slightly surprising, as the code is only running at 1200 bps, but the point of this game isn’t to be completely accurate.
Continue reading “Chinese Whispers For Arduino”
Back in the bad old days, if you needed a little bit of custom logic you would whip out a tiny chip known as a PAL. A Programmable Logic Array is just what it sounds like and is the forerunner of modern, unsolderable CPLDs and FPGAs.
PALs and GALs have died off, left to the wastes of the Jameco warehouse, and now it seems the only programmable logic you can buy are huge, 100-pin monstrosities. [Nick] at Arachnid Labs was working on his Tsunami signal generator when a user asked if they could add just one more feature: a programmable divider to count 256 iterations of a clock. This is the perfect application for dumb logic, but if you’re looking for a part that’s not recommended for new designs, you only need to look to old programmable logic.
Enter the Greenpak. [Nick] had a dev kit for these ‘modern PALs’ sitting around and decided to give it a go. They’re small – they max out at 20 pins – but there are a few features that make it a little more interesting than a simple array of AND and OR gates. The Greenpak3 features analog comparators, look-up tables, RC oscillators, counters, and GPIO that will work well enough as circuit glue. They also work at 5V, something you’re just not going to find in more complex programmable logic.
These tiny chips are programmed in a graphical IDE, but the datasheet (PDF) includes full documentation for the bitstream; someone needs to write a Verilog or VHDL compiler for it soon. The one downside with these chips is that they’re tiny; 0.4mm pitch QFN packages. If you can solder that, you’re too good at soldering.
[Michael] sells a remote control spy tank through his company, and although it’s a toy, there’s an impressive amount of electronics in this R/C tank. It’s controlled from an Android or iDevice over a WiFi connection, something that simply won’t do if you’re trying to sell this to the hacker and maker crowd. The solution to this problem is Wireshark, and with a little bit of work this spy tank can be controlled from just about anything, from a microcontroller via WiFi to a Python app.
Wireshark, everyone’s favorite network packet analysis and capture tool, was used to listen in on the communications between an iPad and the tank. This immediately showed the video stream coming from the camera in the tank, and pointing VLC to the correct port displayed the video.
The motors in the tank were a little trickier, but looking at the data stream, a few packets stood out as being responsible for controlling the motors. After a little experimentation the simple command set was decoded and a Python app whipped up.
These spy tanks are cheap – about $70 from [Michael]’s company and the other usual vendors. It’s not a particularly useful piece of hardware, but someone out there is sure to do something cool with this bit of reverse engineering.
Between all the media coverage of using 3D printers for human prosthetics, some individuals are making a difference for animals too by using 3D printing. And here’s one we really didn’t expect; a replacement shell for a tortoise!
We’ve all seen the heartwarming articles about pups getting wheels, or dogs getting replacement sprung feet — but is there any love for [Cleopatra] the Tortoise? Canyon Critters Rescue is an animal rescue based out of Golden, Colorado. The founder [Novelli] had recently took in little [Cleopatra] who had a painful and dangerous bone disease where her shell peaks and gets worn out — and without a shell to protect her, could easily become infected. This is typically caused by poor nutrition, so the rescue fixed her diet, but the damage to her shell was already done.
At a public education program for the rescue, [Novelli] made an offhand comment about how cool it would be to 3D print a replacement shell for her to protect the weak spots. Lucky enough for [Cleopatra], someone from the Colorado Technical University was there and wanted to help.
First they 3D scanned [Cleopatra’s] shell, and then created a 3D model of it optimized for 3D printing. They printed miniature test models on a MakerBot, and once satisfied printed the entire thing in 4 pieces. It fits over top of original shell, protecting the weak areas.
It was an incredible learning experience for all involved, and [Novelli] was extremely grateful for the help he received from the community:
I am grateful to all these people volunteering their time and energy to help me. At the rescue I don’t have the resources or funds to do something of this scale.
As for [Cleopatra], she’s living a happy tortoise life once again — and since she’s only in her teens, she has nearly a century of life to look forward to with thanks to 3D printing.
A team of adventurous biohackers have successfully played with an interesting type of chlorophyll, called Chlorin e6 by putting it in their eyes… and the result? Well, they kind of obtained night vision.
Say what? Chlorin e6 is a chlorophyll analog that is found in deep-sea fish, and has been used to treat night blindness in humans (patent). There’s actually lots of research done with the substance, and it has even been used to treat different cancers — but most of the research was performed on lab rats.
So the team decided to take the next step — [Gabriel Licina] volunteered, and they squirted 50uL of e6 into his wide-stretched eyes. It kicks in after about an hour, so they headed outside at night to test his vision capabilities. They started by identifying basic shapes at 10 meters away, no larger than the size of his hand. Then they tried even larger distances. They had people stand at a tree line in different places, and [Gabriel] standing 50 meters away was able to point them out. The control group could barely identify them even a third of the time.
They’ve published a research paper on their findings, and it’s quite the interesting read. Perhaps in the future this can be manufactured in eye drop form for special use cases like hunting, military, or even search and rescue.
[Frank] has a Ultimaker2 and wanted to install a new bootloader for the microcontroller without having physical access to the circuitry. That means installing a new bootloader for the ATMega2560 without an In System Programmer, and as is usual on AVRs, the bootloader can only be edited with an ISP. Additionally, modifying the bootloader in any way runs the risk of corruption and a bricked circuit. That’s okay, because [Frank] knows how to do it, and he’s here to show you how.
You can think of the memory layout of the ATMega in the Ultimaker as being split in half, with the printer firmware in the first half and the bootloader in the second half. There’s extra space in both halves, and that’s something that comes in very useful. When the circuit powers up, it jumps to the bootloader, does it’s thing, then jumps to the very beginning of the application code – a vector table – that starts up the actual firmware.
[Frank]’s trick to adding on to the bootloader is to place the SD card bootloader in the space normally reserved for applications, not where you would expect to find a bootloader. This code is accessed by the stock bootloader jumping into a modified vector table at the beginning of the application data that points to new executable code. That code is the actual SD card bootloader, but because it is in the application part of the memory, it can’t perform Flash writing or erasing. To fix that, a tiny bit of code is tacked onto the end of the bootloader for performing Flash writes and jumps back to the application part of memory.
When you need a cold one and walking downstairs to your twin-keg refrigerator just won’t do, it’s time to break out the tools to deliver that frothy goodness where it’s needed. And so began [DaveLondres’] inspiring tale of piping beer through the walls of his home.
Now we know what you’re thinking… that beer is going to get mighty warm sitting in long lines from the fridge up to the ground floor. [Dave] thought about that too and designed a double-pipe system to overcome the issue. A run of PVC pipe for each keg connect the in-wall taps to holes drilled in the side of a second-hand fridge. An ingenious branching job yields an extra port for each run which was fitted with computer case fans to keep the cold air circulating. Plastic tubing is snaked inside of the PVC to carry the beer.
Rounding out the craftsmanship on this one is the inclusion of a plumbed drain to whisk away the drippings. If you’re not going to have a beautifully adorned chest-freezer-gone-kegerator in your livingroom this is the best alternative we’ve seen.