General Construction
Made from a thin, semi-rigid plastic that can be easily modified with hand tools, the badge measures 92 mm wide and 29 mm tall, with a depth of 6 mm. On the right-hand side of the plastic frame are two buttons, for power and brightness, with the brightness button also doubling up as a way to select different animations on the badge – more on that later. Also present on the right is a micro USB charging/data port used to program the badge. Dominating the front of the badge is a 48×12 array of LEDs – that’s 576 LEDs, wow! The LEDs are diffused using a bezel of thin plastic; ours was red, but this changes depending on the colour of LED.
Around the back of the badge, we have a magnetic clasp to hold the badge onto clothing without leaving a mark; however, this is quite weak, so the badge also has a traditional pin clasp, which will leave a mark on clothes, but it is unlikely to fall off.
To open the case, we looked to the back and found that it was held in place using a series of tabs that latch into place. We found that the section nearest the pin clasp and buttons was the best place to open the case, using an iFixit spudger kit.
Power
When the case is open, we see a silver plastic pouch, and this is our lithium polymer battery, rated at 3.7 V, but with no identifiable capacity. The good news about the battery is that it is soldered to the main board using tabs, so that means the battery is replaceable, but do be careful as LiPo batteries do not like heat, and may explode. Charging is via a micro USB port, which means that the badge has a controller that bucks 5 V down to something battery-compatible, and a quick look shows it to be a 662K voltage regulator, which has a fixed output of 3.3 V.
Electronics
At the heart of the board is a GD32F150 which, according to the datasheet, is a 32-bit ARM Cortex M3 microcontroller running at 72MHz – quite a bit of power for a badge! We tested the badge with Linux and it identifies as an STM32-compatible board, which means we have access to the full GPIO of the badge, so we can easily re-flash it using the Arduino IDE – if you’re brave enough! There is also 64kB of flash storage and 8kB of SRAM on the board, but another chip just above the GD32F150 is the P25Q16H, for an additional 2MB of flash storage, which is used when the badge is connected to a computer. It stores the manual and Windows drivers for the board.
Software
To program the badge, there is a Windows application. Sadly, there are no macOS or Linux clients but, as mentioned earlier, eager Arduino hackers can program the badge in that manner. We also tried using the Windows for Linux wrapper Wine to run the application, but sadly this did not work.
The application may not win any awards for style, but it works and it can be used to create static or animated designs featuring icons and standard ASCII characters, which the clever hacker can use to create animations for cosplay or integration into props. The badge can store multiple animations and images, which can be selected using a long press on the brightness button. Flashing the badge is simple and takes mere seconds.
Conclusion
This is an useful piece of kit. For the most basic use, this is a great conference badge that will give a full day of use from one charge. Taking it up a notch, we can easily add this board to cosplay and props thanks to its small size and easy-to-access power/battery connections. The small size is also a bonus for 3D printing enclosures, to mask the badge and help it blend into your creation. For the advanced hacker, we have a powerful STM32-compatible microcontroller that can be used to power much more than the LED array.
We tested this badge at two events and it performed admirably. In fact, it drew plenty of attention, with many asking where to purchase it. Now, we purchased ours from Amazon, but the identical item is available via eBay for less than half the Amazon price!
No matter what you may use this for, this is a very hackable piece of kit that will offer many different options for all levels of makers.
Happy hacking!
Other options
There are alternatives to the conference badge that we took apart, and they range in price and dimensions but are all viable, depending on your budget and skill. For those who want a drop-in board, the Inky pHAT board from Pimoroni is a Raspberry Pi-compatible board that offers an E Ink display, which only uses power when updated. The Inky pHAT comes in black and white; yellow, black, and white; or red, black, and white. It can display text and graphics. The screen update time is slow, so no fast-moving graphics, but it is a viable option for a simple conference badge.
Those of us who have a budget can use LED arrays, typically controlled using the MAX7219 controller. These work with the SPI interface, and it means they can be used with Arduino, Raspberry Pi, and micro:bit.
Other alternatives are OLED screens. These are tiny and bright screens but often less than an inch in size! OLED screens can be used with SPI or I2C interfaces, so again they can be used with many different microcontrollers.
The last alternative is firmly in the past, and it is the screen commonly found in late 1990s Nokia phones, such as the 5110. These screens are common on eBay and are easy to work with for most microcontrollers. The only issue with these screens is that their stock is dwindling, so buy one while you can!
