ESP8266

645 Articles

Build An Excellent Coffee Roaster With A Satisfyingly Low Price Tag

January 23, 2018 by 62 Comments

There’s a lot of mysticism around coffee roasting, but in the end it couldn’t be simpler. Take a bunch of beans, heat them up evenly, and stop before they get burned. The rest is details.

And the same goes for coffee roasters. The most primitive roasting technique involves stirring the beans in a pan or wok to keep them from scorching on the bottom. This works great, but it doesn’t scale. Industrial drum roasters heat a rotating drum with ridges on the inside like a cement mixer to keep the beans in constant motion while they pass over a gas fire. Fluidized-bed roasters use a strong stream of heated air to whirl the beans around while roasting them evenly. But the bottom line is that a coffee roaster needs to agitate the beans over a controllable heat source so that they roast as evenly as possible.

My DIY coffee roaster gave up the ghost a few days ago and I immediately ordered the essential replacement part, a hot air popcorn popper, to avert a true crisis: no coffee! While I was rebuilding, I thought I’d take some pictures and share what I know about the subject. So if you’re interested in roasting coffee, making a popcorn popper into a roaster, or even just taking an inside look at a thoroughly value-engineered kitchen machine, read on!

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How Low Can An ESP8266 Go?

January 22, 2018 by 40 Comments

We’ve been tuned into coin cell designs lately given the coin cell challenge, so we were interested in [CNLohr]’s latest video about pushing the ESP8266 into the lowest-possible battery drain with coin cells. The result is a series of hacks, based on a reverse-engineered library and depends on a modified router, but that gets the power consumption down by more than a factor of ten!

Although the ESP8266 has a deep sleep mode that draws only 20 microamps or so, that isn’t as rosy as it seems. If you could go to sleep for a while, wake up for just a moment, send your data, and then go back to sleep, that might be one thing. But when you use conventional techniques, the device wakes up and has to do about ten seconds of work (at high power) to connect to a nearby access point. Then it can do what you want and go back to sleep. That ten-second hit is a killer on small batteries.

Since that’s all you can do with the standard libraries, the next step was to find [pvvx] who has reverse engineered a great deal of the libraries and provides a library with no WiFi capability. That’s a two-edged sword. The pro is you get a 30 ms startup from a deep sleep. The downside is — well — you don’t have WiFi.

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ESP8266 Beacon Announces Your Arrival

January 21, 2018 by 68 Comments

It used to be people were happy enough to just have to push a button in their car and have the garage door open. But pushing a button means you have to use your hands, like it’s a baby toy or something. We’re living in the 21st century, surely there must be a better way! Well, if you’ve got a home automation system setup and a spare ESP8266 laying around, [aderusha] may have your solution with MQTTCarPresence.

The theory of operation here is very clever. The ESP8266 is powered via the in-dash USB port, which turns on and off with the engine. When the engine is started, the ESP8266 is powered up and immediately connects to the WiFi network and pushes an MQTT message to Home Assistant. When Home Assistant gets the notification that the ESP8266 has connected, it opens the garage door.

When [aderusha] drives out of the garage and away from the house, the ESP8266 loses connection to the network, and Home Assistant closes the door. The same principle works when he comes home: as the car approaches the house it connects to the network and the garage door opens, and when the engine is shut off in the garage, the door closes again.

The hardware side of the setup is really just a WeMos D1 mini Pro board, though he’s added an external antenna to make sure the signal gets picked up when the vehicle is rolling up. He’s also designed a very slick 3D printed case to keep it all together in a neat little package.

We’ve covered automated entry systems based on the ESP8266 before, though usually the ESP stays at home. Be sure to check out the awesome series [Elliot Williams] has on the wonders of MQTT if you’re looking to setup your own automation system.

Solenoids And Servos For Self Actuated Switches

January 18, 2018 by 56 Comments

The new hotness in home automation is WiFi controlled light switches. Sure, we’ve had computer-controlled home lighting for literally forty years with X10 modules, but now we have VC money pouring into hardware, and someone needs to make a buck. A few years ago, [Alex] installed WiFi switches in a few devices in his house and discovered the one downside to the Internet of Light Switches — his light switches didn’t have a satisfying manual override. Instead of cursing the darkness for want of an Internet-connected candle, [Alex] did the only sensible thing. He installed electromagnets, solenoids, and servos behind the light switches in his house.

The exact problem [Alex] is trying to solve here is stateful wall switches. With an Internet-connected lamp socket, the wall switch no longer functions. Being able to turn on a light when your phone is out of charge is something we all take for granted, and the solution is, of course, to have Internet-connected switches.

Being able to read the state of a switch and send some data off to a server is easy. For this, [Alex] used a WeMos D1 mini, a simple ESP8266-based board. The trick here, though, is stateful switches that can toggle themselves on and off. This is a mechanical build, and although self-actuated switches that can flip up and down by computer command exist, they’re horrifically expensive. Instead, [Alex] went the DIY route, first installing electromagnets behind the switches, then moving to solenoids, and finally designing a solution around four cheap hobby servos. The entire confabulation stuffed into a 2-wide electrical box consists of two switches, four hobby servos, the D1 mini, and an Adafruit servo driver board.

The software stack for this entire setup includes a NodeJS server connected to Orvibo Smart Sockets over UDP. Also on this server is a WebSocket server for browser-based clients that want to turn the lights on and off, a FauXMo server to turn the lights on and off via an Amazon Echo via WeMo emulation, and an HTTP server for other clients like [Alex]’ Pebble Watch.

This is, without question, the most baroque method of turning a lamp on and off that we’ve ever seen. Despite this astonishing complexity, [Alex] has something that is also intuitive to use and, to borrow an applhorism, ‘Just Works’. With a setup like this, anyone can flick a switch and turn a lamp on or off over the Internet, or vice-versa. This is the best Home Automation build we’ve ever seen.

You can check out [Alex]’ video demo of his build below, or his GitHub for the entire project here.

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Capture The Flag Challenge Is The Perfect Gift

January 18, 2018 by 7 Comments

Nothing says friendship like a reverse engineering challenge on unknown terrain as a birthday present. When [Rikaard] turned 25 earlier this year, his friend [Veydh] put together a Capture the Flag challenge on an ESP8266 for him. As a software guy with no electronics background, [Rikaard] had no idea what he was presented with, but was eager to find out and to document his journey.

Left without guidance or instructions, [Rikaard] went on to learn more about the ESP8266, with the goal to dump its flash content, hoping to find some clues in it. Discovering the board is running NodeMCU and contains some compiled Lua files, he stepped foot in yet another unknown territory that led him down the Lua bytecode rabbit hole. After a detour describing his adjustments for the ESP’s eLua implementation to the decompiler he uses, his quest to capture the flag began for real.

While this wasn’t [Rikaard]’s first reverse engineering challenge, it was his first in an completely unknown environment outside his comfort zone — the endurance he demonstrated is admirable. There is of course still a long way down the road before one opens up chips or counts transistors in a slightly more complex system.

Less Dear Heating For The Deer

January 13, 2018 by 21 Comments

Keeping animals from tropical regions of the world in a cold climate is an expensive business, they need a warm environment in their pens and sleeping areas. Marwell Zoo was spending a small fortune keeping its herd of nyalas (an antelope, not as the title suggests a deer, native to Southern Africa) warm with electric heating, so they went looking for a technology that could reduce their costs by only heating while an animal was in its pen.

One might expect that a passive IR sensor would solve the problem, but a sleeping nyala too soon becomes part of the background heat for these devices, and as a result, the heaters would not operate for long enough to keep the animals warm. The solution came from an unlikely source, a coffee queue monitoring project at the IBM Watson headquarters in Munich, that used an array of infra-red sensors to monitor the changing heat patterns and thus gauge the likelihood of a lengthy wait for a beverage.

In the zoo application, an array of thermal sensors hooked up to ESP8266 boards talk back to a Raspberry Pi that aggregates the readings and sends them to the IBM Watson cloud where they are analyzed by a neural net. The decision is then made whether or not a nyala is in the field of view, and the animal is toasted accordingly.

This project has some similarities with a Hackaday Prize entry, automated wildlife recognition, in its use of Watson.

Nyala image: Charlesjsharp [CC BY-SA 4.0 ].

3D Print A Home Automation Switch

January 13, 2018 by 15 Comments

If you are the kind of person who won’t use cheap Sonoff modules to control AC powered devices, we don’t blame you and you should probably stop reading now. However, if you don’t mind a little exposed AC wiring and you have a 3D printer, you might be interested in the second generation of [530 Project’s] in-wall light switch.

The 3D printed switch fits a standard box and uses the guts of a Sonoff controller. These work with all the popular ecosystems such as Alexa and Google Home. And they are cheap. Like, really cheap. If you already have a 3D printer, even counting the cost of the filament these are going to be a small fraction of the cost of a commercial switch. You can see a video about the device, below.

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