So You Bought A Raspberry Pi Compute Module. What Now?

The Raspberry Pi Compute Module hasn’t seen as much attention as it should have in our community, probably because the equivalents from the familiar consumer range can be so much cheaper. When a Raspberry Pi Zero is a similar size to a Compute Module and costs so much less, we can’t blame you for asking what would be the point of using the industrial version.

It’s interesting then to see an Instructables piece from [Manolis Agkopian] in which he takes the reader through the process of creating their own Compute Module project. Following hot on the heels of the recent launch of the latest in the range it’s come to us at an appropriate moment to take a fresh look at the fruity computer’s more obscure incarnation. He starts with a description of the Compute Module and its official development board, before taking us through setting up a module and putting an OS on it. Finally he shows us his board design, which he offers us as a jumping-off point for our own projects.

So given that it’s piqued your interest, why might you want to design a Compute Module project? The answer’s simple enough: the consumer boards only provide the subset of features the Pi foundation people deemed appropriate for their mission. A Compute Module project is the equivalent of designing a Raspberry Pi that does it your way, tailored exactly for your needs. If you want an example, look no further than this stereoscopic camera.

Via Hacker News.

This Tiny Router Could be the Next Big Thing

It seems like only yesterday that the Linksys WRT54G and the various open source firmware replacements for it were the pinnacle of home router hacking. But like everything else, routers have gotten smaller and faster over the last few years. The software we run on them has also gotten more advanced, and at this point we’ve got routers that you could use as a light duty Linux desktop in a pinch.

But even with no shortage of pocket-sized Linux devices in our lives, the GL-USB150 “Microrouter” that [Mason Taylor] recently brought to our attention is hard to ignore. Inside this USB flash drive sized router is a 400 MHz Qualcomm QCA9331 SoC, 64 MB of RAM, and a healthy 16 MB of storage; all for around $20 USD. Oh, and did we mention it comes with OpenWRT pre-installed? Just plug it in, and you’ve got a tiny WiFi enabled Linux computer ready to do your bidding.

On his blog [Mason] gives a quick rundown on how to get started with the GL-USB150, and details some of the experiments he’s been doing with it as part of his security research, such as using the device as a remote source for Wireshark running on his desktop. He explains that the diminutive router works just fine when plugged into a USB battery bank, offering a very discreet way to deploy a small Linux box wherever you may need it. But when plugged into a computer, things get really interesting.

If you plug the GL-USB150 into a computer, it shows up to the operating system as a USB Ethernet adapter and can be used as the primary Internet connection. All of the traffic from the computer will then be routed through the device to whatever link to the Internet its been configured to use. Depending on how you look at it, this could be extremely useful or extremely dangerous.

For one, it means that something that looks all the world like a normal USB flash drive could be covertly plugged into a computer and become a “wiretap” through which all of the network traffic is routed. That’s the bad news. On the flip side, it also means you could configure the GL-USB150 as a secure endpoint that lets you quickly and easily funnel all the computer’s traffic through a VPN or Tor without any additional setup.

We’ve seen all manner of hacks and projects that made use of small Linux-compatible routers such as the TP-Link TL-MR3020, but we expect the GL-USB150 and devices like it will be the ones to beat going forward. Let’s just hope one of them doesn’t show up uninvited in your network closet.

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A Science Lab In Your Pocket?

Since even the cheapest phone or computer now has plenty of horsepower, there’s been a move to create instruments that can do everything, using a reasonably simple front end and crunching data back on the host device. This is one of those tasks that seems easy, but doing it well turns out to be a lot of effort. One we recently noticed was Pocket Science Lab — a board that connects to your PC or Android phone and provides an oscilloscope, a logic analyzer, a wave generator, a power supply, a multimeter, and a few odd items such as an accelerometer, barometer, compass, and lux meter. The cost is about $65, so it isn’t a big investment. But what can it do? Read on, or you can watch the video below from Geekcamp Singapore.

The datasheet shows a reasonable device, although nothing amazing. The oscilloscope has 4 channels but only does 2 MSPS, so assuming the front end can handle it, you might visualize 1 MHz sine waves. There’s also a 12-bit voltmeter, three 12-bit power supplies with different ranges, a 4 MHz 4 channel logic analyzer, two sine or triangle wave generators, 4 PWM outputs, and the ability to measure capacitance. Finally, there’s a frequency counter that’s good to 16 MHz.

The 4 channels on the scope are welcome but the low sample rate isn’t. Also, it doesn’t say in the datasheet, but one of the biggest problems with devices like these is that you can’t use major functions together. For example, we bet you can’t use the scope and the logic analyzer at the same time.

For the price, it isn’t a bad deal. But it really isn’t a proper replacement for nearly any of the included virtual instruments. On the other hand, for under $70 it might be worth a shot. There’s a Linux app, so that’s a plus. We like that it is all open source so you could fix anything you don’t like.

You can see a run through of logging data from the light meter on the FOSSASIA channel. They also have a video on the waveform generator.

The Analog Discovery 2 is nicer looking, but not open source and much more expensive. It also has better specs. Of course, you don’t need a PC to have a universal instrument.

 

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This Chromecast Volume Knob Has a Certain ’70s Chic

Chromecast devices have become popular in homes around the world in the last few years. They make it easy to cast audio or video from a smartphone or laptop, to a set of speakers or a display connected to the same network. [Akos] wanted to control the volume on these devices with a single, simple piece of equipment, rather than always reaching for a smartphone. Thus was built the CastVolumeKnob.

The project began by using Wireshark to capture data sent by the pychromecast library. Once [Akos] understood the messaging format, this was implemented in MicroPython on an ESP8266. A rotary encoder is used as a volume knob, and a Neopixel ring is used for visual feedback as to the device being controlled and the current volume level.

Further work was done to improve usability, with an ATtiny85 microcontroller being used to monitor the encoder for button presses before waking up the ESP8266, greatly reducing power consumption. The device is also rechargeable, thanks to an 18650 lithium polymer battery, and charger and boost converter boards. It’s all wrapped up in a sleek 3D printed case, with a translucent bezel for the LEDs and a swanky machined aluminium knob as the cherry on top.

It’s a homemade device that nonetheless would be stylish and unobtrusive in the living room environment. We imagine it proves very useful when important phone calls come in and it’s necessary to cut the stereo down to a more appropriate volume.

For another take, check out this USB volume knob with a nice weighty feel, courtesy of lead shot.