Building An ESP8266 Doorbell On Hard Mode

It certainly seems as though it should be an easy enough project; all [Miguel De Andrade] wanted was to receive a notification when somebody was pressing his doorbell, and thought it would be a good project to get his feet wet in the wonderful world of ESP8266 hacking. But as fate would have it, not everything went according to plan. In the end he got it sorted out, but it’s an interesting look at how even the “easy” projects can call the gremlins out of hiding.

Arguably, the problems started when [Miguel] picked up an ESP-01 module from a local electronics retailer. While the convenience of buying the hardware in a brick and mortar store can’t be overstated, it did mean he was stuck with a slightly more spartan experience compared to the more common ESP “development boards”. Programming it externally with a Teensy ended up not being much of an obstacle, but it did mean he was stuck with only two GPIO pins.

At any rate, with ESP in hand, the next step was figuring out how the existing bell and intercom system even worked. Unfortunately, after some experimentation [Miguel] found there was a bit more going on there than he’d hoped. According to his multimeter, the one line from the intercom sits at approximately 5 VDC when it’s open, and drops down to 2.5 VDC when pressed. If that wasn’t bad enough, picking up the handset to answer the intercom sent the voltage up to a microcontroller-killing 12 VDC. To complicate maters further, the supply line for the intercom was 23 VAC, so he’d need to rectify that somehow if he wanted to avoid a separate power supply for the ESP.

To turn this jumble of voltages into a nice clean 0 – 3.3 V signal for the ESP8266, he came up with a circuit based around the LM358 comparator that utilizes an LM117 regulator to power itself and the ESP at the same time. A couple of diodes are there to block the AC component from causing trouble, and an A2N2222A transistor is used as a buffer amplifier to boost the output of the comparator so it registers as a digital HIGH on the ESP. The circuit took a bit of fiddling to get sorted out, but in the end [Miguel] says it seems to get the job done.

You might think the problems were solved, but this is where it gets really annoying. The system would work fine for awhile, and then inexplicably go silent. In diagnosing the problem he realized that his circuit connected to GPIO_0 was inadvertently putting the ESP8266 into programming mode, since it was holding the pin LOW unless the intercom button was pressed. He assumed he could just move the circuit to the other GPIO pin, but as that one has the board’s LED on it, that caused its own problems. For now, [Miguel] hasn’t come up with a solution to this issue, and has learned to live with the fact that the system won’t come back up cleanly should it lose power for any reason.

If you’re looking for a slightly classier look than a scrap of perfboard stuck on the wall with what appears to be chewing gum, we’ve also seen the ESP8266 used in some more ornate doorbell setups. Of course if you still haven’t gotten your head wrapped around the whole Internet-connected button thing, you can always start with something a little easier.

Wiring The ESP-32 To Ethernet

Since its introduction years ago, the ESP-8266 has taken over the world. It’s the chip inside thousands of different projects, and the basis for dozens of different IoT thingamadoos. The follow-up to the 8266, the ESP-32, is even more capable. It has a ton of peripherals inside, including an Ethernet MAC. What’s that? Yes, it’s possible to put Ethernet on an ESP-32, and give an IoT board PoE. That’s what [Patrick] is doing for his Hackaday Prize project, and it’s an awesome idea.

This build began as you would expect, with an ESP-32 module attached to one side of a board with some breakouts for the GPIOs and a USB to Serial chip. The tricky part here is the PoE part of the Ethernet, which requires MagJack Ethernet connectors, a flyback transformer, and a PoE-PD controller. These were expensive parts, and the design of such a board requires some thinking — you need isolation across the transformer, and proper ground planes for this mess.

There’s something slightly brilliant about using an ESP-32 in a wired configuration. Far too often, we see these modules used as wireless nodes in a sensor net. The battery consumption is significant, and all those makers are adding USB power input to their fancy WiFi sensor nets. If you’re running wires for power anyway, why not add Ethernet and do away with all that mucking around with WiFi setup. It’s a great project, and one of the better entries in this year’s Hackaday Prize.

Turning Cheap WiFi Modules Into Cheap WiFi Swiss Army Knives

When the ESP8266 was released, it was sold as a simple device that would connect to a WiFi network over a UART. It was effectively a WiFi modem for any microcontroller, available for just a few bucks. That in itself is awesome, but then the hackers got their hands on it. It turns out, the ESP8266 is actually a very capable microcontroller as well, and the newest modules have tons of Flash and pins for all your embedded projects.

For [Amine]’s entry to the Hackaday Prize, he’s using the ESP8266 as the ultimate WiFi Swiss Army knife. The Kortex Xttend Lite is a tiny little WiFi repeater that’s capable of doing just about anything with a WiFi network, and with a bit of added hardware, can connect to Ethernet as well.

The hardware on this board sports an ESP8266-07S module, with two free GPIO pins for multiple functions. There’s a USB to UART in there, and a voltage regulator that’s capable of outputting 600mA for the slightly power hungry radio. There’s also an integrated battery management and charge controller, allowing this board to charge an off-the-shelf lithium cell and run for hours without any wires at all.

So, what can this board do? Just about everything you would want for a tiny little WiFi Swiss Army knife. There’s traffic shaping, port mapping, packet sniffing, and even support for mesh networking. There’s also an SMA connector on there, so grab your cantennas — this is a great way to extend a WiFi network, too.

This is a well-designed and well-executed project, and what makes this even more amazing is that this was done as one of [Amine]’s high school projects. Yes, it took about a year to finish this project, but it’s still amazing work for [Amine]’s first ‘high-complexity’ design. That makes it an excellent learning experience, and an awesome entry to this year’s Hackaday Prize.

Reprogramming Cheap WiFi Outlets

If you want to retrofit your home with smart outlets and lightbulbs, bust out your wallet. You can easily spend forty dollars for a smart light bulb at your local home supply store, and strips of smart sockets could cost sixty. When [coogle] found a WiFi-enabled four-outlet power strip on Amazon, he couldn’t resist. Sure, the no-name strip would be locked down behind a stupid iPhone interface and will probably turn your house into a botnet, but never mind that: you can easily reprogram these power strips to be whatever you want.

After receiving these power strips and tearing them open, [coogle] found exactly what you would expect from a no-name white goods manufacturer. There’s a board with an Espressif chip and a WiFi antenna, and a second board with a few relays, with a few wires connecting the two. You only need to browse AliExpress for a few minutes to figure out what’s going on here. The brains of the outfit are in the ESP8266, and if you can control that, you have your own Internet of Power Strips.

The problem, then, was reprogramming the ESP8266. This was a version of the chip [coogle] hadn’t seen before, but a quick query with the Google Mother Brain revealed it was a WT8266-S1 module, with all the pins required for programming easily accessible on a convenient header. After connecting this header up to an ESP programming board, [coogle] had all the relevant information including the capacity of the Flash. There’s still a bit more work to make this a functional WiFi power outlet, namely figuring out which GPIOs and wires connect to which relays, but this is effectively a completely Open IoT device right now. All you have to do is bring your own firmware.

Friday Hack Chat: Everything About The ESP

When the ESP-8266 first arrived, it was a marvel. For two dollars, you could buy a simple module that could serve as a bridge between WiFi networks and microcontroller projects. It understood the Hayes command set, it didn’t use much power, and, as noted before, it only cost two dollars. The idea of cheap and accessible Internet of Things things was right there for the taking.

Then hackers figured out what was actually going on inside the ESP-8266. It was a full-blown microcontroller. There was Lua stuff you could put on it. You could program it with the Arduino IDE. It had WiFi. This was the greatest microcontroller release in the last decade, and it came from a company no one had ever heard of.

Since then, the ESP ecosystem has bloomed, and there’s a new ESP on the block. The ESP-32 is an even more powerful WiFi and Bluetooth-enabled chip that’s just as easy to program, and it costs three dollars. Microcontrollers have never been cooler.

For this week’s Hack Chat, we’re going to be talking all about the ESP. Our guest for this Hack Chat should need no introduction, but if you’re unfamiliar, [Sprite_tm] plays video games on his keyboard and has installed Linux on a hard drive. He also works at Espressif, the company behind the ESP-8266 and ESP-32, where he’s applied his skills towards tiny Game Boys and miniature Macs.

During this week’s Hack Chat, we’re going to be covering everything about the ESP, including peripherals, ultra-low power consumption, SIP packages, and what’s coming up for the ESP family. You are, as always, welcome to submit your questions for [Sprite]; just add those as a comment on the Hack Chat page.

join-hack-chat

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging. [Sprite]’s in China, so we’re not doing this one at the usual time: This week, the Hack Chat will happen at 7:00 am, Pacific, Friday, March 9th. Want to know what time this is happening in your neck of the woods? Have a countdown timer!

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

Fridge Alarm Speaks, and Saves Power & Food

One of the most power-hungry devices in our homes, besides the air conditioner or heater, is our refrigerator and freezer. It’s especially so if the door doesn’t close all the way or the magnetic seal doesn’t seat properly. [Javier] took to solving a recurring problem with his personal fridge by attaching an alarm to the door to make sure that it doesn’t consume any more power than it absolutely needs.

At its core the device is straightforward. A micro switch powers a small microcontroller only when the door is open. If the door is open for too long, the microcontroller swings into action. The device then powers up a small wireless card (which looks like a variant of the very well-documented ESP module), that communicates with his microwave of all things, which in turn alerts him with an audible, spoken alarm that the refrigerator hasn’t closed all the way. It’s all powered with a battery that will eventually need to be recharged.

While there are certainly easier ways to implement an alarm, the use of the spoken alarm is a nice touch for this project, and the power savings that can be realized are not insignificant. There’s also the added benefit that [Javier] can prevent his freezer from frosting over. If you’re in the mood for other great fridge hacks, there are other exciting, novel, and surely one-of-a-kind ways to trick out your refrigerator.

Continue reading “Fridge Alarm Speaks, and Saves Power & Food”

New Part Day: Pluggable ESP Modules

Almost exactly four years ago, we came across a really neat module for sale on SeeedStudios. It was a $5 WiFi chip, able to connect your microcontroller project to the Internet with just a handful of wires and a few AT commands. This was the ESP8266, and it has since spawned an entire ecosystem of connected devices.

Now, there’s a new version of the ESP8266 that simply showed up on the Seeed website. Officially, it’s called the, ‘ESP8285 01M Wi-Fi SoC Module’, but you might as well start calling it ‘the Pluggable ESP module’. It’s the smallest ESP8266 module yet at 18mm square, and this one is designed to be plugged into a card-edge connector. It’s eighteen pins of wonder and 1MB of Flash, all ready to be stuffed into the next Internet of Things Thing.

The documentation for this module is sparse, and there isn’t even a mention of it on the AI Thinker website. That said, we can make some reasonable assumptions about what’s going on in this chip and what it can do. This module appears to be based on the ESP8285 SoC. Basically, it’s an ESP8266 with built-in 1MB SPI Flash. There are a handful of GPIOs available, and you should be able to build anything with this module that you could with other ESP8266 modules.

The highlight here is, of course, the card-edge connector. This is a module designed to be dropped into an existing product. You can program the module before hand, and assembly is a snap. The problem, though, is sourcing the relevant connector. It doesn’t look like Seeed has bothered to put a link to the right connector in the product description, although sourcing it shouldn’t be that much of a problem. The only question is if the card edge connectors on this module are hard gold (for multiple mating cycles) or just ENIG. Either way, if you’re plugging these modules into connectors dozens of times, you’re probably doing something wrong.