Looking at Displays

Despite my interest in hardware projects largely stemming from a desire to get away from screens – those of my many laptops, desktops, tablets, and phones, I’m fairly obsessed with displays for microcontrollers and single-board computers (SBCs), and I’ve had a fair number of them arrive for review at Boards HQ recently. My favourite are non-traditional displays, like the memory LCD used in my beloved Pebble, where each pixel acts as write-only storage to form a literal display buffer. Enclosed please find some of the more interesting displays and display-adjacent hardware to come across my desk of late…

Table of Contents

• 6 MOTION

• 60 LEDs

• LVGL 9

• U55

6 MOTION

I’ve been a big fan of Croatian e-paper afficionados Soldered Electronics for a while now. Their maker-focused displays typically feature Wi-Fi and other peripherals that make them ideal for desktop dashboards and other passive information displays. They are often made from upcycled Kindles, and always have great Arduino compatibility, documentation, and examples. The one limitation of e-paper, as anyone who has an e-reader can attest, is its slow refresh rate compared to other display types – more often measured in seconds per frame than frames per second. So this new board 6 Motion board caught my eye the moment that I turned it on, as it rapidly redrew its various demo screens. A custom frame, built-in buttons, and a 3d-printed LED-backlit jog dial give it the appearance of a finished consumer product, meaning you can just add code to create your own attractive dashboard, information appliance, monochrome picture frame, or whatever you desire. Motion detection, an accelerometer, and WS2812B RGB LEDs expand the board’s possibilities even further, and an STM32H743ZIT6 Cortex-M7 microcontroller gives it serious grunt for just about any application. I was lucky enough to get my hands on a preview version to play with this month, though the production unit should start shipping in October.

60 LEDs

I love Seeed’s XIAO series of teeny-tiny dev boards, and it feels like they keep coming out with new ones based around each of my favourite microcontrollers. But as much fun as they are with the built-in sensors, things get even more interesting when you add extension boards (the XIAO equivalent to Arduino shields or Pi HATs)! And their new 6x10 RGB Matrix extension board is the most fun of all, with (ok, I guess it was kind of implied by the name) 60 tiny 1x1mm WS2812B addressable RGB LEDs crammed into the 21x17.5mm XIAO form factor – perfect for wearables, cosplay, or … I don’t know … a Jumbotron for ants? All I know is that I’m having a blast with it!

LVGL 9

I’ve also been really excited by LVGL lately, ever since I was reminded of it by the Elecrow CrowPanel’s built-in demos. I was blown away by the performance and richness of the UI; LVGL (an initialism for Light and Versatile Graphics Library) provides pre-built widgets and styling that lets your microcontroller projects look and feel like a cutting-edge smartphone app or web page. And with tools like SquareLine Studio, you can design and prototype your display, then export it as C or MicroPython code for use on your CrowPanel or Arduino GIGA Display Shield – or even your M5Stack Dial!

U55

Perhaps the coolest and most unique “display” I’ve been playing with lately is Seeed’s SenseCAP Watcher. This one won’t be out for a while – in fact the Kickstarter campaign isn’t even live yet – but I’ve been lucky enough to get my hands on one of the few alpha units that Seeed has produced, and I’m really excited with what I’ve seen so far. One of the ideas I’ve been spending a lot of time thinking about recently is the intersection of large language models and microcontrollers – enabling AI to interact with the physical world, as opposed to web-based tools and apps that just output text or images (usually with the wrong number of fingers). Watcher gives us a really interesting preview of this world, with both on-device tinyML models, easily selected from the SenseCraft zoo using the device itself, combined with the powers of an LLM in the cloud via the companion app. This allows users to, for example, say “send me a notification if you see a delivery person in a brown uniform” – instead of having to wait around for UPS to arrive – and without having to write any code or create your own custom hardware. While the device’s ESP32-S3 would be perfectly capable of all sorts of interesting tinyML deployments, what really has me excited about this device is the Himax HX6538, which includes both a Cortex M55 MCU and an Ethos-U55 NPU (neural processing unit) optimized for high-speed inference. Plus to bring us back around to the overarching theme, it has a 1.45” 412x412 pixel touchscreen – though thanks to the the built-in 5MP OV5647 image sensor, it will probably spend more time looking at you than you spend looking at it!

That’s it for this month! What are your favorite displays – either in terms of specific hardware, or just technologies? Are you an LCD lover? An OLED acolyte? An e-paper enthusiast? Drop me at note at [email protected] and tell me which you’d prefer to gaze at all day! See you next time,

David J. Groom, who should probably give his eyes a bit of a rest…

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