wifi

457 Articles

Torturing An Instrumented Dive Watch, For Science

July 18, 2019 by 24 Comments

The Internet is a wild and wooly place where people can spout off about anything with impunity. If you sound like you know what you’re talking about and throw around a few bits of the appropriate jargon, chances are good that somebody out there will believe whatever you’re selling.

Case in point: those that purport that watches rated for 300-meter dives will leak if you wiggle them around too much in the shower. Seems preposterous, but rather than just dismiss the claim, [Kristopher Marciniak] chose to disprove it with a tiny wireless pressure sensor stuffed into a dive watch case. The idea occurred to him when his gaze fell across an ESP-01 module next to a watch on his bench. Figuring the two needed to get together, he ordered a BMP280 pressure sensor board, tiny enough itself to fit anywhere. Teamed up with a small LiPo pack, everything was stuffed into an Invicta dive watch case. A little code was added to log the temperature and pressure and transmit the results over WiFi, and [Kristopher] was off to torture test his setup.

The first interesting result is how exquisitely sensitive the sensor is, and how much a small change in temperature can affect the pressure inside the case. The watch took a simulated dive to 70 meters in a pressure vessel, which only increased the internal pressure marginally, and took a skin-flaying shower with a 2300-PSI (16 MPa) pressure washer, also with minimal impact. The video below shows the results, but the take-home message is that a dive watch that leaks in the shower isn’t much of a dive watch.

Hats off to [Kristopher] for doing the work here. We always love citizen science efforts such as this, whether it’s hardware-free radio astronomy or sampling whale snot with a drone.

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Connecting New York City To The Backbone: Meet NYC’s Mesh Network

June 30, 2019 by 25 Comments

Access to fast and affordable internet is a big issue in the USA, even in a major metropolis such as New York City. Amidst a cartel of ISPs who simply will not deliver, a group of NYC inhabitants first took it upon themselves to ease this situation by setting up their own mesh-based internet connections way back in 2013. Now they will be installing a new Supernode to take the installation base far beyond the current 300 buildings serviced.

As a community project, NYC Mesh is run as a non-profit organization, with its community members supporting the effort through donations, along with partnerships with businesses. Its router hardware consists out of off-the-shelf equipment (with a focus on the Ubiquiti NanoStation NSM5) that get flashed with custom firmware containing the mesh routing functionality.

As this article by Vice mentions, NYC Mesh is one of 750 community-led broadband projects in the US. Many of those use more traditional fixed wiring with distribution lines, but NYC Mesh focuses fully on wireless (WiFi) links with wireless mesh networking. This has the obvious benefit that given enough bandwidth on the Supernodes that hook into the Internet exchange points (IXP) and an efficient mesh routing protocol, it’s quick and easy to hook up new clients and expand the network.

The obvious downsides of using WiFi and RF in general is that they are not immune to outside influences, such as weather (rain), RF interference (including from other WiFi stations) and of course fairly limited range if there’s no direct line of sight. In a densely populated city such as NYC this is not much of an issue, with short hops between roof tops.

Breakout Board Becomes Pogo Pin Programmer

May 18, 2019 by 9 Comments

Making a programming jig becomes exponentially more difficult after two pins and who would even consider building one if they were not setting up more than twenty boards? If it were easy for novices to construct jigs, we might all have a quiver of them on the shelf next to our microprocessors. Honestly, a tackle box full of homemade programming fixtures sounds pretty chic. The next advantage to ditching the demo boards is that bare processors take up less room and don’t draw power for unnecessary components like unused voltage regulators and LEDs. [Albert David] improves the return-on-time-investment factor by showing us how to repurpose a WeMos board to program a bare ESP8266 module.

[Albert]’s concept can apply to many other surface-mount chips and modules. The first step is to buy a demo board which hosts a programmable part and remove that part. Since you’ve exposed some solder pads in the process, put pogo pins in their place. Pogo pins are small spring-loaded probes that can be surface mounted or through-hole. We’ve used them for programming gorgeous badges and places where the ESP8266 has already been installed. When you are ready to install your software, clamp your Franken-porcupine to the controller and upload like normal. Rinse, wash, repeat. We even get a view of the clamp [Albert] uses.

WiFi Controlled Plane Is Cheap Flying Fun

April 12, 2019 by 17 Comments

The world of radio controlled aircraft used to be an expensive and exclusive hobby, limited to those with the time and money to invest in difficult builds and pricey radio gear. More recently, the hobby has become more accessible, with cheap ready to fly planes available that can be flown in smaller spaces like suburban parks. [Ravi Butani] has built just such a plane, and you can even fly it with your smartphone!

An ESP8266 does double duty here as both the brains and the communication system. A custom smartphone app communicates with the plane over WiFi. Touching the screen increases the throttle, while steering is achieved through tilting the phone. There’s also monitoring of signal strength and battery level, with the phone vibrating if the plane is getting out of range or low on battery.

Flight control is via differential thrust, with power coming courtesy of two small DC motors controlled by tiny SMD MOSFETs. The plane flies remarkably well in still conditions, and the WiFi connection is stable in an open park environment. [Ravi] reports that control is possible at a range of around 70 meters using a Motorola G5S smartphone.

Despite the simplicity of the build and the low cost of the components, the final product performs admirably. It would be a great weekend project, and at the end of it, you get to go and fly your new plane! If you’re worried about keeping your batteries charged, don’t worry – there’s a solution for that. Video after the break.

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Pocket-Sized Deauther Could Definitely Get You In Trouble

April 4, 2019 by 43 Comments

Interfering with radio communications, whether through jamming, deauthing attacks, or other meddling, is generally considered a crime, and one that attracts significant penalties. However, studying such techniques should provide a useful edge in the electronic wars to come. In this vein, [Giorgio Filardi] has recently built a WiFi deauther the size of a credit card.

The device has a simple interface, consisting of 3 buttons and a small OLED screen. It can also be accessed remotely and controlled through a web interface. A NodeMCU ESP8266 board runs the show, using [spacehuhn]’s deauther firmware. The point-to-point construction probably won’t hold up to much rough and tumble out in the field, but it’s fine for a bench test. We’d recommend constructing an enclosure if it was to be used more regularly.

There’s plenty of functionality baked in – the device can scan for networks, perform deauth attacks, and even create spoof networks. It’s a tricky little device that serves to highlight several flaws in WiFi security that are yet to be fixed by the powers that be.

Using one of these devices for nefarious purposes will likely get you into trouble. Experimenting on your own networks can be educational, however, and goes to show that wireless networks are never quite as safe as we want them to be.

If you’re wondering as to the difference between deauthentication and jamming, here’s your primer.

Library Makes ESP Over The Air Updates Easy

March 21, 2019 by 19 Comments

Potentially, one of the great things about having a device connected to the network is that you can update it remotely. However, how do you make that happen? If you use the Arduino setup for the ESP8266 or ESP32, you might try [scottchiefbaker’s] library which promises to make the process easy.

Adding it looks to be simple. You’ll need an include, of course. If you don’t mind using port 8080 and the path /webota, you only need to call handle_webota() from your main loop. If you want to change the defaults, you’ll need to add an extra call in your setup. You also need to set up a few global variables to specify your network parameters.

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Does WiFi Kill Houseplants?

February 28, 2019 by 72 Comments

Spoiler alert: No.

To come to that conclusion, which runs counter to the combined wisdom of several recent YouTube videos, [Andrew McNeil] ran a pretty neat little experiment. [Andrew] has a not inconsiderable amount of expertise in this area, as an RF engineer and prolific maker of many homebrew WiFi antennas, some of which we’ve featured on these pages before. His experiment centered on cress seeds sprouting in compost. Two identical containers were prepared, with one bathed from above in RF energy from three separate 2.4 GHz transmitters. Each transmitter was coupled to an amplifier and a PCB bi-quad antenna to radiate about 300 mW in slightly different parts of the WiFi spectrum. Both setups were placed in separate rooms in east-facing windows, and each was swapped between rooms every other day, to average out microenvironmental effects.

After only a few days, the cress sprouted in both pots and continued to grow. There was no apparent inhibition of the RF-blasted sprouts – in fact, they appeared a bit lusher than the pristine pot. [Andrew] points out that it’s not real science until it’s quantified, so his next step is to repeat the experiment and take careful biomass measurements. He’s also planning to ramp up the power on the next round as well.

We’d like to think this will put the “WiFi killed my houseplants” nonsense to rest – WiFi can even help keep your plants alive, after all. But somehow we doubt that the debate will die anytime soon.

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