How Small Can The ESP32 Get?

September 7, 2023 by 25 Comments

At its core, the ESP32 chip is not much more than an integrated circuit, a huge mass of transistors sealed inside an epoxy resin package with some leads. Of course, most of us won’t buy discrete ESP32 chips with no support circuitry since it’s typically easier and often not that much more expensive to get them paired with development boards of some type for easy access to things like USB and GPIO. But these tiny chips need little in the way of support to get up and running as [Paul] demonstrates with this tiny ESP32 board.

The project started as a challenge for [Paul] to build the smallest ESP32 that would still function. That means carving away nearly everything normally found accompanying one of these chips. There is no charging circuitry, only one of the GPIO pins is accessible, and it even foregoes the WiFi antennas which eliminates the major reason most people would reach for this chip in the first place. But at this form factor even without wireless capabilities it still blows other chips of this stature, like the ATtiny series, out of the water.

Even though [Paul] built it as a challenge, it goes a long way to demonstrate what’s really needed to get one of these chips up and running properly. And plenty of projects don’t need a ton of I/O or Wi-Fi either, so presuming these individual chips can be found cheaply and boards produced for various projects its an excellent way to minimize size and perhaps even power requirements. You can make these boards even smaller than a USB-A connector if you want to take this process even further, too.

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Streaming Video From An ESP32

September 5, 2023 by 11 Comments

The ESP32, while first thought to be little more than a way of adding wireless capabilities to other microcontrollers, has quickly replaced many of them with its ability to be programmed as its own platform rather than simply an accessory. This also paved the way for accessories of its own, such as various sensors and even a camera. This guide goes over taking the input from the camera and streaming it out over the network to multiple browsers.

On the server side of things, the ESP32 and its attached camera are set up with MQTT, a lightweight communications protocol which uses a publish/subscribe model to send information. The ESP32 is configured to publish its images only, but not subscribe to any other nodes. On the client side, the browser runs a JavaScript program which is able to gather these images and stitch them together into a video.

This can be quite a bit of data to send out over the ESP32’s compact hardware, so there are some tips and tricks for getting more out of these little devices, including using an external antenna for better Wi-Fi signal, or omitting it entirely in favor of Ethernet. As far as getting a lot out of a tiny microcontroller, though, leveraging MQTT really helps the ESP32 go a long way. These chips have come along way since they were first introduced; they’re powerful enough to act as 8-bit gaming consoles too.

Thanks to [Surfskidude] for the tip!

An Open Source Mobile Phone Based On The ESP32

August 24, 2023 by 34 Comments

As microcontrollers become ever faster and cheaper, something we’ve been expecting has been an open source smartphone based not upon a high-end chip, but on a cheap commodity one. In the electronic badge arena we’ve come pretty close, but perhaps it’s left to [Gabriel Rochet] to deliver the first one that brings everything together. His Paxo phone is now on version 4, and while the French-language website link stubbornly resists translation with Google translate, English speakers can find a description of its capabilities along with the software in a GitHub repository.

The hardware is surprisingly straightforward, with a resistive touch screen and a PCB featuring power management, an ESP32 main processor, and a GSM module. The 2G connectivity may not be the fastest, or even available in your country, but otherwise the feature set looks more than reasonable for a basic mobile phone.

We like this project a lot, because as we said it starts to deliver on the promise of the 2018 EMF badge and the 2022 MCH badge. We think the former badge’s designers might find something of interest in it.

Open-Source Cell Phone Based On ESP32

August 3, 2023 by 40 Comments

Over the past decade or so, smartphones have exploded in popularity and seamlessly integrated themselves into nearly every aspect of most people’s lives. Although that comes with a few downsides as well, with plenty of people feeling that the smart phone makes it a little too easy to waste time and looking to switch to something simpler, like an older-style flip phone. If this style of phone is more your speed, take a look at this DIY cell phone which takes care of everything a phone really needs to do. (Google Translate from French)

The phone uses an ESP32 at its core, with a SIM800L GSM modem to interact with the cell network, including retrieving the system time. A small battery is included as well as all of the support circuitry for charging it as well as a USB interface that can communicate to a PC. The operating system for the phone is built from the ground up as well, with a touch screen interface allowing the user to make phone calls, send text messages, store contacts, and a few other basic features. There’s also a GPS application though, allowing the phone to know basic location information.

Another perk of this device is that its creator, [Gabriel], made the design schematics, print files for the case, and the operating system software completely open source for anyone to build this phone on their own. Everything is available on the project’s GitHub page. It’s a fairly remarkable achievement, especially considering [Gabriel] is only 16. And, if you’re not one to eschew modern smart phone technology there are some DIY smart phones available to build as well.

Thanks to [come2] for the tip!

The ESP32 Doesn’t Need Much

July 28, 2023 by 19 Comments

For those looking to add wireless connectivity to embedded projects or to build IoT devices, there is perhaps no more popular module than the ESP32. A dual-core option exists for processor intensive applications, the built-in WiFi and Bluetooth simplify designs, and it has plenty of I/O, memory, and interoperability for most applications. With so much built into the chip itself, [atomic14] wondered how much support circuitry it really needed and set about building the most minimalist ESP32 development board possible.

Starting with the recommended schematic for the ESP32, the most obvious things to remove are a number of the interfacing components like the USB to UART chip and the JTAG interface. The ESP32 has USB capabilities built in, so the data lines from a USB port can be directly soldered to the chip instead of using a go-between. A 3.3V regulator eliminates the need for many of the decoupling capacitors, and the external oscillator support circuitry can also be eliminated when using the internal oscillator. The only thing [atomic14] adds that isn’t strictly necessary is an LED connected to one of the GPIO pins, but he figures the bare minimum required to show the dev board can receive and run programs is blinking an LED.

Building the circuit on a breadboard shows that this minimalist design works, but instead of building a tiny PCB to solder the ESP32 module to he attempted to build a sort of dead-bug support circuit on the back of the ESP32. This didn’t work particularly well so a tiny dev board was eventually created to host this small number of components. But with that, the ESP32 is up and running. These modules are small and compact enough that it’s actually possible to build an entire dev board setup inside a USB module for a Framework laptop, too.

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ESP32 Freezer Alarm Keeps Tabs On Tricky Door

July 27, 2023 by 31 Comments

Leaving your freezer door open accidentally is a great way to make a huge mess in the kitchen. [Guy Dupont] had a freezer that would regularly fail to close properly, and was sick of the regular meltdown events. Thus, he whipped up a very digital solution.

The build combines an ESP32 with a reed switch, which is activated by a magnet on the freezer door. If the freezer door is open, the reed switch similarly remains open. The ESP32 checks the switch status every few minutes, and if the door remains open for two consecutive checks, it raises the alarm. A notification is sent to [Guy] via WiFi so that he can rectify the situation. The rig runs off a 400 mAh battery, which lasts for just over three weeks running door checks at two minute  intervals.

Based on [Guy]’s YouTube video, it appears the freezer door is jamming up against the wall. Perhaps shoving the freezer into a better position would help, though we suspect he would have thought of that first. And, in his own words, “That would be a very boring YouTube video, wouldn’t it?”

It’s not the first fridge alarm we’ve featured, and it won’t be the last, refrigeration gods willing.

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Sand Drawing Plotter Runs On ESP32

July 21, 2023 by 3 Comments

Humans have always drawn lines in the sand, whether it’s to communicate a plan of attack or to indicate metaphorically a very real boundary. It’s also something we do just for the aesthetic pleasure, and this plotter from [aidenvigue] is great at performing in just that role.

The plotter traces patterns in the circular sand tray by dragging a small marble with a magnet. This is achieved with a pair of NEMA 17 stepper motors, set up in a polar coordinate fashion. One stepper motor controls the angle, while another motor controls the marble’s distance from the center point of the circle. It’s a simple way to build a circular plotter, and works far better than a Cartesian setup would for this geometry. The build uses an ESP32 as the brains of the operation. It hosts a web interface that allows various patterns to be selected and run on the device. It also runs a set of addressable SK6812 LEDs that light the sand rather nicely.

We’ve seen some great sand plotters before, and have always been particular fans of the larger variety. Video after the break.

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