Casually Chirping Into The World Of LoRaWAN

January 21, 2022 by Maya Posch 13 Comments

While wireless communications are unquestionably useful in projects, common wireless protocols such as WiFi and Bluetooth peter out after only a number of meters, which is annoying when your project is installed in the middle of nowhere. Moving to an LTE-based or similar mobile solution can help with the range, but this does not help when there’s poor cell coverage, and it tends to use more power. Fortunately, for low-bitrate, low-power wide-area networks (LPWAN) like e.g. sensor networks, there’s a common solution in the form of LoRaWAN, as in long-range wide area network (WAN).

The proprietary LoRa RF modulation technique that underlies LoRaWAN is based on Chirp Spread Spectrum (CSS). This modulation technique is highly resistant to channel noise and fading as well as Doppler shift, enabling it to transmit using relatively low power for long distances. LoRaWAN builds on top of the physical layer provided by LoRa to then create the protocol that devices can then use to communicate with other LoRa devices.

Courtesy of global LoRaWAN gateway and software providers such as The Things Industries and ThingSpeak, it’s possible even as a hobbyist to set up a LoRaWAN-powered sensor network with minimal cost. Let’s take take a look at exactly what is involved in setting up LoRaWAN devices, and what possible alternatives to LoRaWAN might be considered. Continue reading “Casually Chirping Into The World Of LoRaWAN” →

Adding WiFi Remote Control To Home Electronics? Be Prepared To Troubleshoot

January 19, 2022 by Donald Papp 32 Comments

[Alex] recently gave a Marantz audio amplifier the ability to be remotely-controlled via WiFi by interfacing an ESP32 board to a handy port, but the process highlights how interfacing to existing hardware often runs into little, unforeseeable problems that can sink the project unless solved.

At its core, the project uses an ESP32 and the ESPAsyncWebServer project to create a handy web interface that is accessible over WiFi. Then, to actually control the amplifier, [Alex] decoded the IR-based remote signals by watching the unit’s REMOTE ports, which are intended as a pass-through and repeater for IR signals to other Marantz units. This functionality can be exploited; by sending the right signals to the REMOTE IN port, the unit can be controlled by the ESP32. With the ESP32 itself accessible by just about any WiFi device, [Alex] gains the freedom to control his amplifier with much greater flexibility than just the IR remote would offer.

Sounds fairly straightforward, but as usual when interfacing to an existing piece of electronics, there were a few glitches. The first was that high and inconsistent latency (from 10 ms to 100 ms) made controlling the amplifier a sometimes frustrating experience, but that was solved by disabling power saving on the WiFi interface. Another issue was that sending signals by connecting a GPIO pin to the REMOTE IN port of the amplifier worked, but had the side effect of causing the amplifier to no longer listen to the IR remote. Apparently, current flowing from the REMOTE port to the ESP32’s GPIO pin was to blame, because adding a diode in between fixed the problem.

The GitHub repository holds the design files and code. This kind of project can be pretty complex, because the existing hardware doesn’t always play nice, and useful boards like a modern ESP32 aren’t always available. Adding a wireless interface to vintage audio equipment has in the past involved etching circuit boards and considerably more parts.

New Pi Zero Gains Unapproved Antennas Yet Again

December 13, 2021 by Arya Voronova 25 Comments

We’ve only started to tap into the potential of the brand new Pi Zero 2. Having finally received his board, [Brian Dorey] shows us how to boost your Pi’s WiFi, the hacker way. Inline with the onboard WiFi antenna can be found a u.FL footprint, and you just know that someone had to add an external antenna. This is where [Brian] comes in, with a photo-rich writeup and video tutorial, embedded below, that will have you modify your own Zero in no time. His measurements show seeing fourteen networks available in a spot where he’d only see four before, and the RSSI levels reported have improved by 5 dB -10 dB, big when it comes to getting a further or more stable connection.

With old laptops being a decent source of WiFi antennas, you only need to procure a u.FL connector and practice soldering a bit before you take this on! The hardest part of such a project tends to be not accidentally putting any solder on the u.FL connector’s metal can – and [Brian] mostly succeeds in that! He shows how to disconnect the external antenna to avoid signal reflections and the like, and, of course, you will be expected to never power your Pi Zero on without an attached antenna afterwards, lest you have your transmitter become fatally confused by the mismatch of hardware-defined impedance expectations. A Pi Zero isn’t the only place where you’ll encounter footprints for connectors you can add, and arguably, that’s your duty as a hacker – modifying the things you work with in a way that adds functionality. Don’t forget to share how you did it!

This trick should be pretty helpful if you’re ever to put your new Pi Zero in a full-metal enclosure. Curious about the Raspberry Pi antenna’s inner workings? We’ve covered them before! If you’d like to see some previous Raspberry Pi mods, here’s one for the Pi 3, and here’s one for the original Zero W – from [Brian], too!
Continue reading “New Pi Zero Gains Unapproved Antennas Yet Again” →

Visualizing WiFi With A Converted 3D Printer

November 22, 2021 by Dan Maloney 9 Comments

We all know we live in a soup of electromagnetic radiation, everything from AM radio broadcasts to cosmic rays. Some of it is useful, some is a nuisance, but all of it is invisible. We know it’s there, but we have no idea what the fields look like. Unless you put something like this 3D WiFi field strength visualizer to work, of course.

Granted, based as it is on the gantry of an old 3D printer, [Neumi]’s WiFi scanner has a somewhat limited work envelope. A NodeMCU ESP32 module rides where the printer’s extruder normally resides, and scans through a series of points one centimeter apart. A received signal strength indicator (RSSI) reading is taken from the NodeMCU’s WiFi at each point, and the position and RSSI data for each point are saved to a CSV file. A couple of Python programs then digest the raw data to produce both 2D and 3D scans. The 3D scans are the most revealing — you can actually see a 12.5-cm spacing of signal strength, which corresponds to the wavelength of 2.4-GHz WiFi. The video below shows the data capture process and some of the visualizations.

While it’s still pretty cool at this scale, we’d love to see this scaled up. [Neumi] has already done a large-scale 3D visualization project, using ultrasound rather than radio waves, so he’s had some experience in this area. But perhaps a cable bot or something similar would work for a room-sized experiment. A nice touch would be using an SDR dongle to collect signal strength data, too — it would allow you to look at different parts of the spectrum.

Continue reading “Visualizing WiFi With A Converted 3D Printer” →

So. What’s Up With All These Crazy Event Networks Then?

November 11, 2021 by Jenny List 21 Comments

As an itinerant Hackaday writer I am privileged to meet the people who make up our community as I travel the continent in search of the coolest gatherings. This weekend I’ve made the trek to the east of the Netherlands for the ETH0 hacker camp, in a camping hostel set in wooded countryside. Sit down, connect to the network, grab a Club-Mate, and I’m ready to go!

Forget the CTF, Connecting To WiFi Is The Real Challenge!

There no doubt comes a point in every traveling hacker’s life when a small annoyance becomes a major one and a rant boils up from within, and perhaps it’s ETH0’s misfortune that it’s at their event that something has finally boiled over. I’m speaking of course about wireless networks.

While on the road I connect to a lot of them, the normal commercial hotspots, hackerspaces, and of course at hacker camps. Connecting to a wireless network is a simple experience, with a level of security provided by WPA2 and access credentials being a password. Find the SSID, bang in the password, and you’re in. I’m as securely connected as I reasonably can be, and can get on with whatever I need to do. At hacker camps though, for some reason it never seems to be so simple.

Instead of a simple password field you are presented with a complex dialogue with a load of fields that make little sense, and someone breezily saying “Just enter hacker and hacker!” doesn’t cut it when that simply doesn’t work. When you have to publish an app just so that attendees can hook up their phones to a network, perhaps it’s time to take another look . Continue reading “So. What’s Up With All These Crazy Event Networks Then?” →

Rolling Your Own Long-Range IoT Sensor Network

November 11, 2021 by Tom Nardi 7 Comments

Homebrew wireless sensors are nothing new around these parts: grab an ESP8266, hang a BME280 from the I2C pins, and you’re just a few lines of code away from joining the Internet of Things on your own terms. Builds like this are so cheap and easy that they make an excellent first project for folks looking to get into the electronics game, but what if you’re looking for something a bit more bespoke?

In that case, you could follow in the footsteps of [Discreet Mayor] and put together a custom modular architecture for long-range wireless sensors. The core of the system is a breakout board for the Texas Instruments SimpleLink CC1312 wireless MCU which features a simple 2×11 header connector. This allows the module to either be plugged into a larger board or have a small sensor PCB attached directly to it.

Rather than using WiFi or requiring some existing radio infrastructure, the boards automatically create a private network using the IEEE 802.15.4 standard at a range of up to 600 meters. A dedicated receiver isn’t necessary, to pull data off the network, one of the CC1312 boards simply gets connected to a computer through a simple FT232 adapter.

[Discreet Mayor] has already created a number of projects that use these custom radios for communication, from a pool monitoring system to a temperature sensor for the BBQ. That portable battery operated devices are able to use this common communications backbone just as well as mains powered static devices is a testament to the work that went into the firmware to make it as robust and efficient as possible.

Like the idea of long-range private networks, but less enthusiastic about having to come up with your own hardware? Not to worry. Over the summer, Espressif announced that they’re working on an ESP32 variant that includes support for IEEE 802.15.4. Just as soon as this chip shortage is over, we might even get to see the thing.

Download From NFC Datalogger, No App Required

September 23, 2021 by Danie Conradie 14 Comments

The plethora of wireless technologies has made internet-connected devices the norm, but it’s not always necessary if you don’t need real-time updates. Whether it’s due to battery life, or location and range constraints, downloading data directly from the device whenever possible might be a viable solution. [Malcolm Mackay] demonstrates an elegant solution on the open source cuplTag temperature/humidity logger, using any NFC-enabled smartphone, without requiring a custom app.

The cuplTag utilizes the feature on NFC-enabled smartphones to automatically open a URL provided by the cuplTag. It encodes the sensor data from the sensor unit as a circular buffer in a ~1 kB URL, which automatically uploads to a web frontend that plots the data. (You can use their server or run your own.)

This means that data can be collected by anyone with the appropriate phone with zero setup. The data is displayed on the web app and can be downloaded as a CSV. To deter spoofing, each tag ships with a secret key which is used to generate a unique HMAC every time the circular buffer changes.

Battery life is a priority on the cuplTag, and it’s theoretically capable of running seven years on a single CR1220 coin cell using the current-sipping Texas Instruments MSP430 microcontroller. The hardware, firmware, and server-side frontend and backend code are all open source and available on GitHub.

Earlier this year, we held a data logging contest, and featured submissions that monitored everything from your garden’s moisture levels to your caffeine intake.