A clock with an e-paper display in a 3D-printed case

Low Power Challenge: E-Paper Shelf Label Becomes Ultra-Frugal Clock

February 24, 2023 by Robin Kearey 12 Comments

Over the past two decades, e-paper has evolved from an exotic and expensive display technology to something cheap enough to be used for supermarket price tags. While such electronic shelf labels are now easy to find, actually re-using them is often tricky due to a lack of documentation. Luckily, [Aaron Christophel] has managed to reverse engineer many types of shelf labels, and he’s demonstrated the results by turning one into an ultra-low-power clock called Triink. It’s based on a 128×296 pixel e-ink display paired with an nRF52832 BlueTooth Low-Energy SoC and uses just 65 micro-amperes on average: low enough to keep it running for more than a year on a single battery charge.

A PCB for an e-ink clock — Power on the left, e-ink on the right: the custom PCB is clever and compact, too

The clock is housed in an enclosure that’s simple but effective: a 3D-printed triangular prism with a slot for the screen and space for the 18650 lithium battery. One side can be opened to access the internal components, although that’s really only needed to charge the battery. You can see how cleverly everything snaps together in the video embedded below. Continue reading “Low Power Challenge: E-Paper Shelf Label Becomes Ultra-Frugal Clock” →

Low Power Challenge: Weather Station Runs For Months Thanks To E-Ink Display

February 20, 2023 by Robin Kearey 2 Comments

Having a device in your living room that shows weather information is convenient, and building one of those is a great project if you enjoy tinkering with microcontrollers and environmental sensors. It’s also a great way to learn about low-power design, as [x-labz] demonstrated with their e-ink weather station which works for no less than 60 days on a single battery charge. It has a clear display that shows the local temperature and humidity, as well as the weather forecast for the day.

The display is a 4.2″ e-paper module with a resolution of 400 x 300 pixels. It uses just 26 mW of power for a few seconds while it updates its image, and basically zero watts when showing a static picture. It’s driven by a tiny ESP32C3 processor board, which downloads the weather forecast from weatherapi.com every two hours. The indoor climate is measured by an SHT-21 temperature and humidity sensor mounted behind the display, while the outdoor data is gathered by a WiFi-connected sensor installed on [x-labz]’s balcony.

The key to achieving low power usage here is to keep the ESP32 in sleep mode as much as possible. The CPU briefly wakes up once every five minutes to read out the indoor sensor and once every fifteen minutes to gather data from outside, using the relatively power-hungry WiFi module.

To further reduce power consumption, the CPU core is driven at the lowest possible clock speed at all times: 10 MHz when reading the indoor sensor, and 80 MHz when using the WiFi connection. All of this helps ensure that just one 600 mAh lithium battery can keep everything running for those 60 days.

E-ink displays are perfect for text and simple graphics that don’t change too often, which is why they’re very popular in weather stations. With a bit of tweaking though, LCDs can also be optimized for low power.

When Pi Supply Falls Short, Thin Clients Stand Tall For Home Automation And Low Power Computing

November 25, 2022 by Ryan Flowers 80 Comments

Do you need a cheap, small computer for a low power computing project? Historically, many of us would reach straight for a Raspberry Pi, even if we didn’t absolutely need the GPIO. But with prices elevated and supplies in the dumps, [Andreas Spiess] decided that it was time to look for alternatives to now-expensive Pi’s which you can see in the video below the break.

Many simply use the Pi for its software ecosystem, its lower power requirements, and diminutive size. [Andreas] has searched eBay, looking for thin PC clients that can be had for as little as $10-15. A few slightly more expensive units were also chosen, and in the video some comparisons are made. How do these thin clients compare to a Pi for power consumption, computing power, and cost? The results may surprise you!

Software is another issue, since many Pi projects rely on Raspbian, a Pi-specific ARM64 Linux distribution. Since Raspbian is based on Debian, [Andreas] chose it as a basis for experimentation. He thoughtfully included such powerful software as Proxmox for virtualization, IOTstack, and Home Assistant, walking the viewer through each step of running Home Assistant on x86-64 hardware and noting the differences between the Linux distributions.

All in all, if you’ve ever considered stepping out of the Pi ecosystem and into general Linux computing, this tutorial will be an excellent starting point. Of course [Andreas] isn’t the first to bark up this tree, and we featured another thin client running Klipper for your 3D printer earlier this month. Have you found your own perfect Pi replacement in these Pi-less times? Let us know in the comments below.

Continue reading “When Pi Supply Falls Short, Thin Clients Stand Tall For Home Automation And Low Power Computing” →

battery powered wall mounted clock with LCD display and 10 capacitive touch buttons

A Peppy Low Power Wall Mounted Display

September 19, 2022 by Abe Connelly 18 Comments

[Phambili Tech] creates a battery powered mountable display, called “the Newt”, that can be used to display information about the time, calendar, weather or a host of other customizable items.

The Newt tries to strike a balance between providing long operating periods while still maintaining high refresh rates and having extensive features. Many of the battery powered devices of this sort use E-Ink displays which offer long operating windows but poor refresh rates. The Newt uses an LCD screen that, while not being as low power as an E-Ink display, offers extended battery operation while still being daylight readable and providing high refresh rates.

The display itself is a 2.7 inch 240×400 SHARP “Memory In Pixel” LCD that provides the peppy display at low power. The Newt is WiFi capable through its ESP32-S2-WROVER module with a RV-3028-C7 Real Time Clock, a buzzer for sound feedback and capacitive touch sensors for input and interaction. A 1.85Wh LiPo battery (3.7V, 500mAh) is claimed to last for 1-2 months, with the possibility of using a larger battery for longer life.

Continue reading “A Peppy Low Power Wall Mounted Display” →

Turing Pi 2: The Low Power Cluster

June 16, 2022 by Jonathan Bennett 39 Comments

We’re not in the habit of recommending Kickstarter projects here at Hackaday, but when prototype hardware shows up on our desk, we just can’t help but play with it and write it up for the readers. And that is exactly where we find ourselves with the Turing Pi 2. You may be familiar with the original Turing Pi, the carrier board that runs seven Raspberry Pi Compute boards at once. That one supports the Compute versions 1 and 3, but a new design was clearly needed for the Compute Module 4. Not content with just supporting the CM4, the developers at Turing Machines have designed a 4-slot carrier board based on the NVIDIA Jetson pinout. The entire line of Jetson devices are supported, and a simple adapter makes the CM4 work. There’s even a brand new module planned around the RK3588, which should be quite impressive.

One of the design decisions of the TP2 is to use the mini-ITX form-factor and 24-pin ATX power connection, giving us the option to install the TP2 in a small computer case. There’s even a custom rack-mountable case being planned by the folks over at My Electronics. So if you want 4 or 8 Raspberry Pis in a rack mount, this one’s for you.
Continue reading “Turing Pi 2: The Low Power Cluster” →

Low Power Mode For Custom GPS Tracker

March 28, 2022 by Bryan Cockfield 19 Comments

GPS has been a game-changing technology for all kinds of areas. Shipping, navigation, and even synchronization of clocks have become tremendously easier thanks to GPS. As a result of its widespread use, the cost of components is also low enough that almost anyone can build their own GPS device, and [Akio Sato] has taken this to the extreme with efforts to build a GPS tracker that uses the tiniest amount of power.

This GPS tracker is just the first part of this build, known as the air station. It uses a few tricks in order to get up to 30 days of use out of a single coin cell battery. First, it is extremely small and uses a minimum of components. Second, it uses LoRa, a low-power radio networking method, to communicate its location to the second part of this build, the ground station. The air station grabs GPS information and sends it over LoRa networks to the ground station which means it doesn’t need a cellular connection to operate, and everything is bundled together in a waterproof, shock-resistant durable case.

[Akio Sato] imagines this unit would be particularly useful for recovering drones or other small aircraft that can easily get themselves lost. He’s started a crowdfunding page for it as well. With such a long battery life, it’s almost certain that the operator could recover their vessel before the batteries run out of energy. It could also be put to use tracking things that have a tendency to get stolen.

Wireless, Low Power E-Ink Weather Gadget

March 2, 2021 by Donald Papp 14 Comments

Not that long ago, making a low-power and wireless weather display complete with an e-ink screen would have required a lot of work and almost certainly would have been larger than the device [Dmitry] created.

(1) Weather alert indicator, (2) Current temperature, (3) Humidity and wind, (4) 24-hour temperature graph, (5) 24-hour precipitation probably graph

His low power e-ink weather gadget takes advantage of one of the niftier developer boards out there to create a useful and slim device that does exactly what he needs and not a lick more. It’s fast to look up weather online, but not as fast as glancing at a display in a convenient location.

The board [Dmitry] selected is a LilyGO TTGO T5s, an ESP32-based board that integrates an e-ink display, which requires no power unless being updated. It has been loaded with just enough smarts to fetch weather information using the OpenWeather API, and update the display accordingly.

Powering up the WiFi to fetch an easily-parsed JSON file and update the display only once per hour means that a battery can provide months of runtime. As a bonus, the LilyGO board even includes the ability to charge the battery, making things awfully convenient.

The bill of materials is here and code for the device, including setup directions, is on the project’s GitHub repository. And if your tastes happen to run more towards the artistic than utilitarian, we have just the weather display for you.