The Raspberry Pi Pico W disrupted the status quo in mid-2022. For a time we were satisfied with the Raspberry Pi Pico. For $4, it brought a lot of computing power, but it lacked something that ESP32 and ESP8266 owners had, Wi-Fi. The Raspberry Pi Pico W’s higher price, $6 versus $4, saw an extra $2 bring Wi-Fi and many more opportunities to the tiny microcontroller.
Pimoroni capitalized on the Pico W and released a range of Pico W Aboard products, from small sensor platforms to a Inventor’s inspiration. The Pimoroni team also teased a new “Unicorn” board. Pimoroni has a history of releasing Unicorn themed products. The original Unicorn HAT is the first, but the latest is the $50 Galactic Unicorn which sees the Raspberry Pi Pico W power an incredible 538 RGB LEDs.
But is this Unicorn a one-trick pony or do we have a thoroughbred on our hands? To learn it we need to saddle up and take it for a test ride.
Galactic Unicorn Hardware Specifications
|SoC||RP2040 Arm Cortex M0+ Dual Core at 133 MHz|
|Storage||2 MB flash|
|Connectivity||2.4 GHz Wi-Fi|
|GPIO||2 x QW/ST connectors (Stemma QT / Qwiic)|
|583 RGB LEDs (53 x 11 matrix)|
|MAX98357 3.2W I2S mono amplifier (with 30mm 1W speaker)|
|9 x buttons|
|JST-PH Battery Connector (5.5 V Max)|
|Dimensions||330 x 78 x 10.3 mm|
Use Galactic Unicorn
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As always, Pimoroni really delivers on the hardware and software experience. Before we delve into the review, let’s take a moment to acknowledge the silkscreen print on the PCB. The illustration is great, and the print is sharp. It ties the product together and gives us much more than just a PCB to admire. On the print side, we can see the Raspberry Pi Pico W surface mount soldered to the main PCB, with buttons for user input (A to D), volume, brightness and a handy reset button (which we must admit we forgot on a few occasions). Around the perimeter is a series of M2-sized mounting holes. It can be used to attach the included metal legs, for use on a desk. Pimoroni also provides a DXF file that has the exact position of these holes. The DXF file can be used to laser cut a case for Galactic Unicorn. The same file can easily be a template for a 3D printed container. For the daring among you, there’s even a lanyard attachment to maximize your impact at the next social gathering/conference.
Flashing the custom Pimoroni UF2 Pico firmware gives us a wealth of options to interact with the Galactic Unicorn and many other accessories. From there it was just a matter of tinkering with the examples provided to get a feel for how it works. The best example of how this all works is in the features.py project code. Here we get a demo of all the RGB pixels, inputs and a surprisingly capable speaker that managed to crank out a great 8-bit tune.
The stars of the show, all 538 of them, are the RGB LEDs. Running at 300 fps, these 14-bit RGB LEDs are powered by the Raspberry Pi Pico W’s Programmable IO (PIO) and apply gamma correction on the fly.
So what does that mean? If you’ve ever tried to record a video or take a photo of an RGB LED, you’ll know how difficult it is to get around the flickering generated by them. With Galactic Unicorn we don’t have that problem. With no shutter speed fiddling, we had rock solid scrolling text.
For our review, we created a script that would read the Tom’s Hardware RSS feed and scroll the headlines about the rather fancy LED matrix. We modified the scroll text example, added network access and used the urequests module to parse a JSON object (we used an online tool to parse the RSS into JSON) and from there we got the values from the JSON -object extracted.
The next test involved a BME688 temperature sensor connected to the Galactic Unicorn’s QW/ST connectors. Within minutes we had live temperature, humidity and air pressure readings in our home with just one easily hidden connector. The QW/ST connections are Voice QT / Qwiic compatible and provides access to the I2C interface. Aside from the buttons, the QW/ST connectors are the only way to interface with Galactic Unicorn.
This does limit what we can connect to mainly products that follow the QW/ST, StemmaQT, Qwiic form factor, of which there are many from Pimoroni, Adafruit and SparkFun. You can get StemmaQT to male jumper wire adapters for use with I2C devices or for basic GPIO access. We would have liked some more GPIO pins. We can get by with I2C, but just a few more pins broken out for use would be nice.
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Galactic Unicorn is not all about sound and the 20mm 1W speaker may not offer a THX certified experience, but the sounds it makes are wholesome and refer to a simpler era. The MAX98357 I2S mono amplifier does an excellent job of boosting the sound to audible levels. The speaker’s position on the PCB sees a series of holes cut into it, to provide the best possible volume. The Galactic Unicorn is capable of good sound quality, somewhat similar to a high quality musical greeting card.
Galactic Unicorn Projects
If you need a YouTube subscriber counter, scrolling news ticker, 8-bit retro wall art, then Galactic Unicorn is for you. Heck, even a new conference badge would be a great build with Galactic Unicorn. The alternatives for Galactic Unicorn build our own through a HUB75 LED matrix and a Raspberry Pi / Raspberry Pi Pico W.
If gaming is more your thing, then perhaps the ultimate flexibility is a pixelated version of Mario across the sprawling matrix. With individual control of the pixels and buttons on the perimeter of the board we were able to make our own pixel tributes to the classics. Widescreen Pacman will be especially fun.
No matter what your ambitions are, Galactic Unicorn wraps it all in a thin and very stylish package with none of the wiring hassles. Laser cutting our 3D print your own container should be a breeze thanks to the downloadable DXf files.
The Pimoroni Galactic Unicorn is more expensive than a true DIY option, but the extra dollars provide convenience and a truly smooth experience. We don’t have to worry about wiring and compiling our own code. It’s ready to go with the minimum of effort. It is much more than a text scroller.
It could be your information tracker, GitHub commit streak reporter, or even playing a really big version of Flappy Birds. The hardware is solid and the software supports it beautifully. Because it uses MicroPython, we have access to many more code modules, but Pimoroni’s initial selections are solid and provide us with enough to get us started on making a cool project.