Wireless Hacks

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Four images in one. Top left is an image of four individuals in a room with whiteboards and desks in the background along with various clutter on the floor. Over the people is a wireframe overlay of their poses. The image on the top right is just the wireframe people on a black background. Bottom left image is of a single individual standing in a room with the pose wireframe overlay. Bottom right image is the single pose wireframe on a black background.

Tracking Humans With WiFi

January 26, 2023 by 45 Comments

In case you thought that cameras, LiDAR, infrared sensors, and the like weren’t enough for Big Brother to track you, researchers from Carnegie Mellon University have found a way to track human movements via WiFi. [PDF via VPNoverview]

The process uses the signals from WiFi routers for an inexpensive way to determine human poses that isn’t hampered by lack of illumination or object occlusion. The system produces UV coordinates of human bodies by analyzing signal strength and phase data to generate a 2D feature map and then feeding that through a modified DensePose-RCNN architecture which corresponds to 3D human poses. The system does have trouble with unusual poses that are not in the training set or if there are more than three subjects in the detection area.

While there are probably applications in Kinect-esque VR Halo games, this will probably go straight into the toolbox of three letter agencies and advertising-fueled tech companies. The authors claim this to use “privacy-preserving algorithms for human sensing,” but only time will tell if they’re correct.

If you’re interested in other creepy surveillance tools, checkout the Heat-Sensing Crotch Monitor or this Dystopian Peep Show.

Wireless CNC Pendant Implemented With ESP-NOW

January 7, 2023 by 6 Comments

As a fervent fan of twiddly and twirly widgets and tactile buttons in a device’s user interface, [Steve M Potter] created a remote control (pendant) for his CNC machine, which he explains in a recent video that’s also linked down below. In addition to all the tactile goodness, what is perhaps most interesting about this controller is that it uses Espressif’s ESP-NOW protocol. This still uses the same 2.4 GHz as WiFi would, but uses a system more akin to the pairing of a wireless mouse or keyboard.

Advantages of ESP-NOW include the lower power usage, longer range, no requirement for a router and WiFi SSID & password. As far as latency goes, [Steve] measured a round-trip latency of 2.4 ms, which is fast enough for this purpose. Since it does control a potentially dangerous machine, all transmissions are acknowledged and re-transmitted at higher power if needed.

The lower power usage means that the pendant will last a lot longer on a single charge from the 18650 Li-ion cell, while ESP-NOW’s fixed address pairing saves time when turning the pendant on. Meanwhile, on the CNC side, another ESP32 acts as the receiving end for commands, although theoretically an ESP8266 could be used as well, if size or power was a concern there.

As for the transparent enclosure? It’s to make it easier to show it off to interested folk, apparently.

Continue reading “Wireless CNC Pendant Implemented With ESP-NOW” →

A small brown PCB with various components on it. There is a headphone cable and DC barrel connector cable coming out of it.

Put Your Serial Port On The Web

January 7, 2023 by 37 Comments

Today, everything from your computer to your dryer has wireless communications built in, but devices weren’t always so unencumbered by wires. What to do when you have a legacy serial device, but no serial port on the computer you want to connect? [vahidyou] designed a wireless serial dongle to solve this conundrum.

Faced with a CNC that took instructions over serial port, and not wanting to deal with the cabling involved in a serial to USB adapter, [vahidyou] turned to an ESP8266 to let his computer and device talk wirelessly. The hand-made PCB connects via a 3.5 mm headphone jack to DB9 adapter which he describes in another article. While [vahidyou] did write a small Windows program for managing the device, it is probably easier to simply access it in a web browser from any device you have handy.

Want to see another wireless serial port application? This Palm Portable Keyboard Bluetooth dongle will let you type in comfort on the go, or you can use a PiModem to get your retrocomputer online!

Fritzing diagram of connections between the Wemos D1 board, the TP4056 board, the pushbutton and the LiIon battery

Battery-Powered ESP8266 Sensor? Never Been Simpler

December 31, 2022 by 23 Comments

Say, you’re starting your electronics journey with a few projects in mind. You have an ESP8266 board like the Wemos D1, a Li-Ion battery, you want to build a small battery-powered sensor that wakes up every few minutes to do something, and you don’t want to delve into hardware too much for now. Well then, does [Mads Chr. Olesen] have a tutorial for you! Here, you’ll learn the quick and easy way to get your sensor up and running, learn a few tricks for doing sleep Arduino environment, and even calculate how long your specific battery could last. Continue reading “Battery-Powered ESP8266 Sensor? Never Been Simpler” →

Supercon 2022: Mooneer Salem Goes Ham With An ESP32

December 28, 2022 by 10 Comments

After being licensed as a ham radio operator since the early 2000s, you tend to start thinking about combining your love for the radio with other talents. In a 20-minute talk at Hackaday Supercon 2022, [Mooneer Salem] tells the story of one such passion project that combined software and radio to miniaturize a digital ham radio modulator.

[Mooneer] works as a software developer and contributes to a project called FreeDV (free digital voice), a digital voice mode for HF radio. FreeDV first compresses the digital audio stream, then converts it into a modulation scheme sent out over a radio. The appeal is that this can be understandable down to very low signal-to-noise ratios and includes metadata and all the other niceties that digital signals bring.

Traditionally, this has required a computer to compress the audio and modulate the signal in addition to two sound cards. One card processes the audio in and out of your headset, and another for the audio coming in and out of the radio. [David Rowe] and [Rick Barnich] developed the SM1000, a portable FreeDV adapter based around the STM32F4 microcontroller. However, flash space was running low, and the cost was more than they wanted. Continue reading “Supercon 2022: Mooneer Salem Goes Ham With An ESP32” →

Connecting Commercial 433 MHz Sensors To MQTT And Home Assistant With RTL-SDR

December 26, 2022 by 37 Comments

When [Elixir of Progress] was looking at setting up environmental sensors around their home to keep track of temperature, humidity and such, the obvious ideas of using WiFi-connected sensors didn’t work due to lack of WiFi range. Although Zigbee (Z-wave) sensors have longer range than WiFi, they are decidedly more expensive, proprietary and require a special transceiver hub. That’s where 433 MHz sensors for weather stations come into the picture.

The idea is simple: virtually all of those sensors – many of them rated for outdoor use – use the unlicensed 433 MHz spectrum that can easily be captured using cheap RTL-SDR (software defined radio) USB dongles. With the data stream from these sensors captured, the open source rtl_433 project enables automatic decoding of these data streams for a wide range of supported sensors.

While Realtek RTL2832-based and other RTL-SDRs can be found for quite cheap, it should be noted that these can run quite hot. Rather than heatsinking the IC, for this project it was elected to only listen sporadically and allow the RTL-SDR receiver to cool down in between listening sessions.

Getting the data from there into Home Assistant, InfluxDB or similar is easy, as rtl_433 can output the decoded data directly to an Influx database, MQTT broker as well as other formats. In this case, the data was sent via MQTT with the Home Assistant instance configured to treat these MQTT topics as sensors. With each sensor’s location carefully registered, this allows for setting up a dense, very low-power network of 433 MHz sensors for monitoring and home automation purposes.

This WiFi Signal Strength Meter Ain’t Afraid Of No Ghosts

December 23, 2022 by 5 Comments

The original Ghostbusters movie is a classic that’s still delivering nearly 40 years after its release — just let that sink in for a minute. Almost every aspect of the film, from hand props to quotes, is instantly recognizable, even to people who haven’t based their lives on the teachings of [Venkman], [Stantz], and [Spengler]. To wit, we present this PKE meter-style WiFi scanner.

Of course, [Kevin McAleer]’s project is strictly in the “Just for Fun” category. But that doesn’t mean it’s not at least somewhat useful. The design is pretty close to the original PKE meter, with a little bit of creative license taken to make it easier to build. Guts include a Raspberry Pi Pico W and a generous 320×240 LCD display. The body of the meter is entirely 3D printed; design files are of course available. The meter’s arms are geared together to move with a single hobby servo.

On the software side, [Kevin]’s GUI lets users see a list of WiFi hotspots in the area and select one from the list. From there, the position of the arms is determined by the RSSI for the hotspot, similar to how the prop was supposed to indicate the proximity to a spook, specter, or ghost. There’s perhaps a bit of a missed opportunity by not adding LEDs to the arms, but we’ll let that slide.

The video below has full design and build details, but fair warning that it’s a bit on the long side. That’s probably just a reflection of how much work [Kevin] put into this, though. Of course, you may rather build a PKE meter that “actually” detects ghosts, in which case we’ve got you covered.

Continue reading “This WiFi Signal Strength Meter Ain’t Afraid Of No Ghosts” →