Which Wireless is Right Wireless?

Back in the early days of Arduino proliferation (and before you ask, yes we realize there was a time before that too), wireless was a strange and foreign beast. IR communication was definitely a thing. And if you had the funds there was this cool technology called ZigBee that was available, often in funny blue house-shaped XBee boards. With even more funds and a stomach for AT commands you could even bolt on a 2G cell radio for unlimited range. WiFi existed too, but connecting it to a hobbyist ecosystem of boards was a little hairier (though maybe not for our readership).

But as cell phones pushed demand for low power wireless forward and the progression of what would become the Internet of marking Terms (the IoT, of course) began, a proliferation of options appeared for wireless communication. Earlier this week we came across a great primer on some of the major wireless technologies which was put together by Digikey earlier in the year. Let’s not bury the lede. This table is the crux of the piece:

There are some neat entries here that are a little less common (and our old friend, the oft-maligned and never market-penetrating ZigBee). It’s actually even missing some entries. Let’s break it down:

  • Extremely short range: Just NFC. Very useful for transferring small amount of sensitive information slowly, or things with high location-relevance (like between phones that are touching).
  • Short range: BLE, Zigbee, Z-Wave, etc. Handy for so-called Personal Area Networks and home-scale systems.
  • Medium/long range: Wifi, Bluetooth, Zigbee, Z-Wave, LoRaWAN: Sometimes stretching for a kilometer or more in open spaces. Useful for everything from emitting tweets to stitching together a mesh network across a forrest, as long as there are enough nodes. Some of these are also useful at shorter range.
  • Very Long range/rangeless: Sigfox, NB-IoT, LTE Category-0. Connect anywhere, usually with some sort of subscription for network access. Rangeless in the sense that range is so long you use infrastructure instead of hooking a radio up to a Raspberry Pi under your desk. Though LoRa can be a fun exception to that.

You’re unlikely to go from zero to custom wireless solution without getting down into the mud with the available dev boards for a few different common protocols, but which ones? The landscape has changed so rapidly over the years, it’s easy to get stuck in one comfortable technology and miss the appearance of the next big thing (like how LoRaWAN is becoming new cool kid these days). This guide is a good overview to help catch you up and help decide which dev kits are worth a further look. But of course we still want to hear from you below about your favorite wireless gems — past, present, and future — that didn’t make it into the list (we’re looking at you 433 MHz).

DIY Linux Computer and 6LoWPAN Gateway

We toss together our own PCB designs, throwing in a microcontroller here or there. Anything more demanding than that, and we reach for a Raspberry Pi or BeagleBone (or an old Linksys router). Why don’t we just whip together a PCB for a small Linux computer? Because we don’t know how…but [Jonas] apparently does. And when we asked him why he did it, he replied “because I can!”

zb

His Ethernet-to-6LoWPAN gateway project is a small, OpenWRT-capable Linux computer in disguise. Rather than yet another Raspberry Pi project, he designed around an Atmel AT91SAM9G25 400 MHz CPU, and added some memory, Ethernet, and a CC2520 radio chip to handle the wireless side. It’s all done on a four-layer board, and hotplate/skillet reflowed. This seems temptingly like something within our reach. [Jonas] had access to X-ray machines to double-check his reflow work, which probably isn’t necessary, although it looks really cool.

When finished, the project will link together a 6LoWPAN network (probably home automation) and his home wired network. That makes this device a rival to something like Philips’ Hue Bridge, which was the subject of some controversy when they locked out other devices for a few days until they recanted. Indeed, in response to this, there’s been quite a lot of effort at hacking the firmware of the Hue device, just to stay on the safe side in case Philips plays shenanigans again.

Soon, that’s not going to be necessary. [Jonas]’s design is open from the ground up, and coupled with open software running on top of the OpenWRT router operating system, that’s the full stack. And that’s great news for folks who are thinking about investing in a home automation technology, but afraid of what happens then the faceless corporations decide to pull the plug on their devices.

Stealing WiFi From LED Lightbulbs

LIFX Wireless LED PCB

Back in 2012, the LIFX light bulb launched on Kickstarter, and was quite successful. This wireless LED lightbulb uses a combination of WiFi and 6LoWPAN to create a network of lightbulbs within your house. Context Information Security took a look into these devices, and found some security issues.

The LIFX system has a master bulb. This is the only bulb which connects to WiFi, and it sends all commands out to the remaining bulbs over 6LoWPAN. To keep the network up, any bulb can become a master if required. This means the WiFi credentials need to be shared between all the bulbs.

Looking into the protocol, an encrypted binary blob containing WiFi credentials was found. This binary could easily be recovered using an AVR Raven evaluation kit, but was not readable since it was encrypted.

After cracking a bulb apart, they found JTAG headers on the main board. A BusBlaster and OpenOCD were used to communicate with the chip. This allowed the firmware to be dumped.

Using IDA Pro, they determined that AES was being used to encrypt the WiFi credentials. With a bit more work, the key and initialization vector was extracted. With this information, WiFi credentials sent over the air could be decrypted.

The good news is that LIFX fixed this issue. Now they generate an encryption key based on WiFi credentials, preventing a globally unique key from being used.

[via reddit]

Porting Contiki to the TI MSP430 Launchpad

For many years Contiki has been one of the main choices when it came to choosing an IPv6 over Low power Wireless Personal Area Networks stack (aka 6LoWPAN). It is developed by a world-wide team of developers with contributions from Atmel, Cisco, ETH, etc… and is open source. As most platforms to which Contiki has been ported are quite expensive, [Marcus] decided to bring the operating system to the TI Launchpad. For our readers that don’t know, the latter is based on a msp430g2452/2553 microcontroller, which only have 256/512 bytes of RAM and 16kB of ROM. As a side note, Contiki typically requires 10k RAM and 30k ROM.

[Marcus] therefore had to remove several features from Contiki: queue-buffering, energy estimation and regrettably uIP. His test setup (shown above) uses the TI CC2500 radio that can be found for less than $2 on Aliexpress, for which he wrote radio drivers from scratch. He also coded his own radio duty-cicling layer, as the one included in Contiki was too big.