How Many Watts Are You Using?

One of the best smart home hacks is implementing an energy monitor of some kind. It’s easy enough to say that you’re trying to save energy, but without the cold hard data, it’s just talk. Plus, it’s easy and a great way to build up something DIY that the whole family can use.

[Bogdan] built up a simple whole-apartment power monitor from scratch over the weekend, and he’s been nice enough to walk us through the whole procedure, starting with picking up a split-core CT sensor and ending up with a finished project.

The brains of his project are an ESP8266 module, which means that he needed to adapt the CT sensor to put out a voltage that lies within the chip’s ADC range of 0 V to 3.3 V. If you’re undertaking an energy monitor project, it’s as easy as picking the right burden resistor value and then shifting the ground-centered voltage up by 1.6 V or so. We say it’s easy, but it’s nice to have a worked example and some scope shots. The microcontroller reads the ADC frequently, does a little math, and you’re done. Continue reading “How Many Watts Are You Using?”

Simple Scanner Finds the Best WiFi Signal

Want to know which way to point your WiFi antenna to get the best signal? It’s a guessing game for most of us, but a quick build of a scanning WiFi antenna using mostly off-the-shelf components could point you in the right direction.

With saturation WiFi coverage in most places these days, optimizing your signal might seem like a pointless exercise. And indeed it seems [shawnhymel] built this more for fun than for practical reasons. Still, we can see applications where a scanning Yagi-Uda antenna would come in handy. The build started with a “WiFi divining rod” [shawnhymel] created from a simple homebrew Yagi-Uda and an ESP8266 to display the received signal strength indication (RSSI) from a specific access point. Tired of manually moving the popsicle stick and paperclip antenna, he built a two-axis scanner to swing the antenna through a complete hemisphere.

The RSSI for each point is recorded, and when the scan is complete, the antenna swings back to the strongest point. Given the antenna’s less-than-perfect directionality — [shawnhymel] traded narrow beam width for gain — we imagine the “strongest point” is somewhat subjective, but with a better antenna this could be a handy tool for site surveys, automated radio direction finding, or just mapping the RF environment of your neighborhood.

Yagi-Uda antennas and WiFi are no strangers to each other, whether it be a WiFi sniper rifle or another recycling bin Yagi.  Of course this scanner isn’t limited to WiFi. Maybe scanning a lightweight Yagi for the 2-meter band would be a great way to lock onto the local Ham repeater.

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A Smart Switch Board For The ESP8266

With a plethora of IoT projects and inexpensive commercial smart light fittings and mains switches appearing, you might be forgiven for thinking that another offering in this crowded marketplace would be superfluous. But there is always room for improvement in any field, and in this particular one [Xose Pérez] has done just that with his Espurna board.

This board is a very well executed ESP8266 mains relay, with an on-board mains power supply and power monitoring. It was designed with his Espurna (“Spark” in Catalan) custom firmware in mind, which offers support for Alexa, Domoticz, Home Assistant and anything that supports MQTT or HTTP REST APIs.

Best of all, it’s a piece of open source hardware, so you can download everything you need from his GitHub repository to create your own. For the ultimate in convenience you can even order the PCB ready-made from OSH Park.

As a demonstration of the Espurna board in a real application, he’s produced a smart socket project neatly enclosed in a wall-wart style box with an inbuilt Euro style plug and socket.

We’ve featured [Xose]’s work several times before here at Hackaday, he’s something of an IoT wizard. Most recently there was his work with Alexa and the ESP8266, but before that was his MQTT LED array for his laundry monitor.

DIY DynDNS with ESP8266 and Dweets

You’re on a home router, and your IP address keeps changing. Instead of paying a little bit extra for a static IP address (and becoming a grownup member of the Internet) there are many services that let you push your current IP out to the rest of the world dynamically. But most of them involve paying money or spending time reading advertisements. Who has either money or time?!

[Alberto Ricci Bitti] cobbled together a few free services and an ESP8266 module to make a device that occasionally pushes its external IP address out to a web-based “dweet” service. The skinny: an ESP8266 gets its external IP address from ipify.org and pushes it by “dweet” to a web-based data store. Freeboard reads the “dweet” and posts the resulting link in a nice format.

Every part of this short chain of software services could be replaced easily enough with anything else. We cobbled together our own similar solution, literally in the previous century, back when we were on dialup. But [Alberto R B]’s solution is quick and easy, and uses no fewer than three (3!) cloud services ending in .io. Add an ESP8266 to the WiFi network that you’d like to expose, and you’re done.

Everyone Loves Faster ESP8266 TFT Libs

Reader [Jasper] writes in with glowing praise for the TFT_eSPI library for the ESP8266 and the various cheap 480×320 TFT displays (ILI9341, ILI9163, ST7735, S6D02A1, etc.) that support SPI mode. It’s a drop-in replacement for the Adafruit GFX and driver libraries, so you don’t need to rework your code to take advantage of it. If you’re looking to drive an LCD screen with an ESP8266 and Arduino, check this out for sure.

As a testbed, [Jasper] ported his Tick Tock Timer project over to the new library. He got a sevenfold increase in draw speed, going from 500 ms to 76 ms. That’s the difference between a refresh that’s visibly slow, and one that looks like it happens instantly. Sweet.

Improving software infrastructure isn’t one of the sexiest or most visible hacks, but it can touch the lives of many hackers. How many projects have we featured with an ESP8266 and a screen? Thanks, [Bodmer] for the good work, and [Jasper] for bringing it to our attention.

Sir, It Appears We’ve Been Jammed!

In a move that would induce ire in Lord Helmet, [Kedar Nimbalkar] has recreated Instructables user spacehun’s version of WiFi jammer that comes with a handful of features certain to frustrate whomever has provoked its wrath.

The jammer is an ESP8266 development board — running some additional custom code — accessed and controlled by a cell phone. From the interface, [Nimbalkar] is able to target a WiFi network and boot all the devices off the network by de-authenticating them. Another method is to flood the airspace with bogus SSIDs to make connecting to a valid network a drawn-out affair.

This kind of signal interruption is almost certainly illegal where you live. It does no permanent damage, but once again raises the existing deauth exploit and SSID loophole. [Nimbalkar]’s purpose in recreating this was for educational purposes and to highlight weaknesses in 802.11 WiFi protocols. The 802.11w standard should alleviate some of our fake deauth woes by using protected frames. Once the device authenticates on a network it will be able to detect fake deauth packets.

We featured a more targeted version of this hack that can be done using a PC — even targeting itself! And more recently there was a version that can target specific devices by jumping on the ACK.

Continue reading “Sir, It Appears We’ve Been Jammed!”

Hacked IoT Switch Gains I2C Super Powers

Economies of scale and mass production bring us tons of stuff for not much money. And sometimes, that stuff is hackable. Case in point: the $5 Sonoff WiFi Smart Switch has an ESP8266 inside but the firmware isn’t very flexible. The device is equipped with the bare minimum 1 MB of SPI flash memory. Even worse, it doesn’t have the I2C ports extra pins exposed so that you can’t just connect up your own sensors and make them much more than just a switch. But that’s why we have soldering irons, right?

Continue reading “Hacked IoT Switch Gains I2C Super Powers”