Old Gas Meter Gets Smart With The ESP8266

January 31, 2021 by 34 Comments

Measuring the usage of domestic utilities such as water, gas or electricity usually boils down to measuring a repetitive pulse signal with respect to time. To make things easy, most modern utility meters have a pulsed LED output, which can be used to monitor the consumption by using an external optical sensor. But what do you do if your meter isn’t so cooperative?

That’s exactly what [Francesco] had to figure out while developing the non-invasive gas tracking system he calls ESPmeter. His meter might not have an LED, but it did have a magnet attached to the counter disk which activated an internal hall sensor. With some hacking, he was able to attach an external Hall-effect sensor to pick up this magnet and use the signal to monitor his daily gas consumption.


A big stumbling block in such projects is the issue of powering the device for an extended period, and remembering when it’s time to change the batteries. With the clever use of commonly available parts, he was able to reduce power consumption allowing three AA batteries to last about a year between changes. For one thing, he uses an ATtiny13 to actually read the sensor values. The chip doesn’t run continuously, its watchdog is set at 1 Hz, ensuring that the device is woken up often enough so that it has time to power up the sensor and detect the presence of the magnet. Battery voltage is also measured via a voltage divider connected to the chip’s ADC pin.

At regular intervals throughout the day, the ESP8266 polls the ATtiny13 to pull the stored sensor pulses and voltage measurement. Then at midnight, the ESP transmits all the collected data to a remote server. Overall, this whole scheme allows [Francesco] to reliably gather his gas consumption data while not having to worry about batteries until he gets the low voltage notification. Since the data visualization requirements are pretty basic, he is keeping things simple by using Plotly to display his time series data.

If you are unfortunate enough to have an even older meter which doesn’t use optical or magnetic rotation sensing, you can use a disassembled mouse to keep track of the Gas Meter.

ESP8266 Socket Is A Snap-Fit, Breadboard-Friendly Wonder

January 10, 2021 by 27 Comments

It all started with wanting to program an ESP-12 variant of an ESP8266 module without involving any solder. Displeased with all the socket offerings on Thingiverse, [tweeto] set out to design their own breadboard-friendly snap-fit socket.

This certainly looks like a handy solution. All you have to do is print the thing, add all the wires, and stick your ESP in there. Even that wire is easy to find; [tweeto] used 0.8 mm paper clips which are sturdy, conductive, and haunting the darkest corners of every desk drawer. They’re also a little bit on the thick side, so [tweeto] plans to test out 0.6mm copper wire in the future.

The challenge with this type of print is to design something that will stand up to repeated breadboardings without losing legs or falling apart. [tweeto]’s elegant solution is a tiny groove for each wire in the bottom of the socket — it keeps the wire in place by countering the play caused by inserting it into and removing it from a breadboard. See how [tweeto] bends the paper clips in the short video after the break.

There’s more than one way to use 3D printing to your circuit-building advantage, even in permanent circuits — just take a look at this PCB-free Arduboy.

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Automating Your Car With A Spare Fob And An ESP8266

January 6, 2021 by 47 Comments

Despite the name, home automation doesn’t have to be limited to only the devices within your home. Bringing your car into the mix can open up some very interesting possibilities, such as automatically getting it warmed up in the morning if the outside air temperature drops below a certain point. The only problem is, not everyone is willing to start hacking their ride’s wiring to do it.

Which is exactly why [Matt Frost] went the non-invasive route. By wiring up an ESP8266 to a cheap aftermarket key fob for his Chevrolet Suburban, he’s now able to wirelessly control the door locks and start the engine without having to make any modifications to the vehicle. He was lucky that the Chevy allowed him to program his own fob, but even if you have to spend the money on getting a new remote from the dealer, it’s sure to be cheaper than the repair bill should you cook something under the dash with an errant splice or a misplaced line of code.

The hardware for this project is about as simple as it gets. The fob is powered by the 3.3 V pin on the Wemos D1 Mini, and the traces for the buttons have been hooked up to the GPIO pins. By putting both boards into a custom 3D printed enclosure, [Matt] came up with a tidy little box that he could mount in his garage and run off of a standard USB power supply.

On the software side of things [Matt] has the device emulating a smart light so it can easily be controlled by his Alexa, with a few helpful routines sprinkled in that allow him to avoid the awkward phraseology that would be required otherwise. There’s also a minimal web server running on the microcontroller that lets him trigger various actions just by hitting the appropriate URLs, which made connecting it to Home Assistant a snap. One downside of this approach is that there’s no acknowledgement from the vehicle that the command was actually received, but you can always send a command multiple times to be sure.

This isn’t the first time we’ve seen an ESP8266 used to “push” buttons on a remote. If you’ve got a spare fob for your device, or can get one, it’s an excellent way to automate it on the cheap.

Espressif Leaks ESP32-C3: A WiFi SoC That’s RISC-V And Is ESP8266 Pin-Compatible

November 22, 2020 by 56 Comments

Six years on from the emergence of the Espressif ESP8266 we might believe that the focus had shifted to the newer dual-core ESP32. But here comes a twist in the form of the newly-revealed ESP32-C3. It’s a WiFi SoC that despite its ESP32 name contains a RISC-V core in place of the Tensilica core in the ESP32s we know, and uses the ESP8266 pin-out rather than that of its newer sibling. There’s relatively little information about it at the time of writing, but CNX Software have gathered together what there is including a draft datasheet whose English translation is available as a Mega download. As with other ESP32 family members, this one delivers b/g/n WiFi and Bluetooth Low-Energy (BLE) 5, where it differs is the RISC-V 32 Single-core processor with a clock speed of up to 160 MHz. There is 400 kB of SRAM and 384 kB ROM storage space built in.

While there is no official announcement yet, Espressif has been dropping hints. There’s been an OpenOCD configuration file for it in the Espressif repositories since the end of last month. And on Friday, Espressif Software Engineering Manager [Sprite_tm] answered a reddit comment, confirming the RISC-V core.

ESP-01: Kjerish, CC BY-SA 4.0, RISC-V logo: RISC-V foundation, Public domain.

Why they are releasing the part as an ESP32 rather than giving it a series number of its own remains a mystery, but it’s not hard to see why it makes commercial sense to create it in an ESP8266-compatible footprint. The arrival of competing parts in the cheap wireless SoC space such as the Bouffalo Labs BL602 we mentioned recently is likely to be eating into sales of the six-year-old chip, so an upgrade path to a more capable part with minimal new hardware design requirements could be a powerful incentive for large customers to stay with Espressif.

We’re left to guess on how exactly the rollout will proceed. We expect to see similar developer support to that they now provide for their other chips, and then ESP32-C3 powered versions of existing ESP8266 boards in short order. It’s also to be hoped that a standard RISC-V toolchain could be used instead of the device-specific ones for current Espressif offerings. What we should not expect are open-source replacements for the blobs that drive the on-board peripherals, as the new chip will share the same closed-source IP as its predecessors for them. Perhaps if the PINE64 initiative to reverse engineer blobs for the BL602 bears fruit, we might see a similar effort for this chip.

ESP8266 Does RC Without The Transmitter

October 30, 2020 by 27 Comments

While the cost of a hobby-grade remote control transmitter has dropped significantly over the last decade or so, even the basic models are still relatively expensive. It’s not such a big deal if you only need to get one for personal use, but for a school to outfit a classroom’s worth of students their own radios, they’d need to have a serious STEM budget.

Which is why [Miharix], himself an educator with a decade of experience, developed a project that leverages the ESP8266 to create affordable RC vehicles that can be controlled with a smartphone’s web browser. There’s a bit of irony at play since the smartphones are more expensive than the RC transmitters would have been; but with more and more school-age kids having their own mobile devices, it takes the cost burden off of the educators. Depending on the age of the students, the teacher would only need to keep a couple of burner phones on hand for student that doesn’t have a device of their own.

A custom PCB makes connections easier for students.

In its fully realized form, the project uses an open hardware board that allows standard RC hobby servos to be connected to the GPIO pins of a ESP-12E module. But if you don’t want to go through the trouble of building the custom hardware, you could put something similar together with an ESP development board. From there it’s just a matter of installing the firmware, which starts up a server providing a touch-based controller interface that’s perfect for a smartphone’s screen.

Since the ESP8266 pops up as an Access Point that client devices can connect to, you don’t even need to have an existing network in place. Or Internet access, for that matter. [Miharix] says that in tests, the range between a common smartphone and the ESP8266 is approximately 85 meters (260 feet), which should be more than enough to get the job done.

In the videos after the break you can see this system being used with an RC car and boat, though the only limit to what you could control with this project is your own imagination.

Continue reading “ESP8266 Does RC Without The Transmitter” →

An Open Source IR Gateway Based On The ESP8266

October 14, 2020 by 26 Comments

The market is absolutely inundated with smart gadgets, with everything from coffee makers to TVs advertising that they support the latest and greatest in home automation platforms. Don’t worry about how many of those platforms and services will still up up and running in the next few years, the thing will probably stop working before then anyway. No sense worrying about the details in a disposable world.

Of course, not all of us are so quick to dump working hardware in the name of the latest consumer trend. Which is why [Viktor] has developed an open source infrared gateway that can connect your “dumb” devices to the latest flash in the pan backend service with nothing more than a software update. Though even modern smart TVs still include IR remotes, so there’s nothing stopping you from using it with newer gear if you don’t trust like the built-in implementation.

The hardware here is really quite simple, essentially boiling down to a few IR LEDs and an IR receiver hanging off the GPIO ports of an ESP8266. While the receiver isn’t strictly necessary, it does allow [Viktor] to rapidly implement new IR codes. He just points the existing remote at the board, hits a button, and the decoded command gets sent out over MQTT where he can easily snap it up.

[Viktor] has done the hard work of creating the PCB design and testing out different IR LEDs to find the ones with the best performance. But if you wanted to just throw something together in a weekend, you should be able to get his firmware running with little more than a bare ESP and a random IR LED salvaged from an old remote. But don’t be surprised if you get hooked on the concept and end up rolling your own home automation system.

ESP8266 Turned Secretive WiFi Probe Request Sniffer

September 20, 2020 by 21 Comments

When a Wi-Fi device is switched on, it starts spewing out probe requests to try and find a familiar access point. These probe requests contain the device’s MAC address and the SSID of the hotspot it’s looking for, which can potentially be used to identify a specific device and where it’s been. After experimenting with these probe requests, [Amine Mehdi Mansouri] has created OpenMAC, a tiny ESP8266 based sniffer that could be hidden anywhere.

The device consists of an ESP-07S module, a regulator circuit for getting power from a USB-C connector, and a button for power cycling. An external antenna is required for the module, which can be selected based on the size or gain requirements for a specific deployment. [Amine] tested the OpenMAC at a local library (with permission), in combination with a number of his own little Wi-Fi repeaters to expand the reach of the network. All the recorded MAC addresses were logged to a server, where the data can be used for traffic analysis in and around the library, or even for tracking and locating specific devices.

This is nothing new, and is relatively common technique used for gathering information in retail locations, and could be also be used for more nefarious purposes. Newer versions of iOS, Android, and Windows 10 feature MAC address randomization which can limit the ability to track devices in this manner, but it isn’t always activated.

We’ve seen a number of projects that exploit probe requests. FIND-LF can be used for locating devices in your home, and Linger fools probe requests sniffers by replaying previously recorded requests.