Arm Wearable E-Ink Badger 2040W Pi Pico Case

This is an enclosure system for an arm or wrist wearable sunlight readable e-paper display microcontroller that you can program for whatever purpose you might have. It is based on the Pimoroni Badger 2040W. I started with Andreas's excellent enclosure model and modified it for clearance to accept USBC charging, designed an all new rear panel with clearance for a flat Lipo cell and the Pimoroni Lipo Amigo Pro USBC to Lipo charge control and on/off switch, and a strap to attach a 3 inch or 8 cm wrist band. A cover was also designed to protect the display and front buttons when not in use. The cover stays on with slight friction, and inverting the wrist band retains it and provides additional padding.

PLA and PETG were used with default settings and no support was needed or used, though some models need to be reoriented with the appropriate side down on the printbed.

A 350 mAh 3.7V protected Lipo cell from Adafruit was used, but other sizes may fit as there is additional clearance. It is attached to the PicoW's Wifi Shield with a small square of 3M VHB tape. The Amigo Pro charge current is 200 mA so it would not be recommended to go below 200 mAh in protected cell capacity. Observe the usual safety protocols with respect to Lipo cells, mistreatment can cause them to get very hot or even catch fire. Do not use unprotected cells.

Hardware used was M2x10 philips type wood screws, 4 for the back and 4 for the wrist strap connection. The wrist strap setup can be omitted if not needed.

Andreas's design has a thin rectangular bezel that fits on the Badger display and allows some compliance with the display location on the PCB within the front panel. Failing to use that part will result in a sloppy fit. He recommends double sided tape to hold it but I found it wasn't needed as it is trapped in place when the unit is properly stacked inside the case. The file for this thin bezel rectangle is in his repo on Printables which is linked via the Model Origin section below.

The Amigo Pro PCB was attached with two small rectangles of 3M VHB tape to the back corner of the Badger as shown in the photo. One corner screw is aligned with the badger screw hole and the M2x10 screw captures both and this locks it in place. Some mylar or electrical tape was used under the Amigo Pro so it could not contact the Pico connections that it slightly overlaps.

The Amigo Pro PCB has two functions, one is to control power to the Badger, the other is to control charging. There is a red LED when charging, and a white LED for dc output to the Badger. The pushbutton on the Amigo Pro can be pushed by depressing the flexible strut/pin on the back corner near the USBC and this controls power to the Badger. A JST PH 2.0 2 pin F-F cable is needed to connect the Amigo Pro power output to the Badger power input. Make sure the positive is routed to the positive on the two connectors. In my case the premade connector to wires I started with had the colors backwards so I had to be especially careful about getting the polarity right even though the wire colors in that cable are wrong. The Adafruit cable has the proper color coding but is a bit long and wasn't in hand when I assembled the project.

Note that the Badger itself has a MicroUSB connection for programming and testing. This does not charge the Lipo but it can power the Badger. Both USB connectors are available on the side. There are two additional Badger PCB pushbuttons on the back, Reset and Bootsel for programming. To reach these requires removing the back cover in this design. Once MicroPython is installed these are not usually accessed.

I used this for making a wearable tennis scorekeeper, but you can use the Badger 2040 W's built in badge programs or make your own MicroPython, CircuitPython or C++ software to customize this to your own purpose. It has Wifi and BT so the possibilities are endless.

Most of the parts in this project are available from the Pishop, Adafruit, Digikey or Pimoroni. M2x10 screws are from Amazon. JST-PH cables were fabricated from Amazon parts, or are available premade from Adafruit or Pimoroni.

Enjoy!