Specter Shield Lite

Specter Shield addon for Specter DIY Bitcoin Hareware Wallet based on the STM32F469I-DISCO board, adding Smart Card capability for enhanced security as well as QR Reader support for data exchange. The functionality is based on the Specter Shield v1.0.0 (Original here: https://github.com/cryptoadvance/specterdiy/blob/master/shield/README.md) and is drop-in compatible with it.

The board itself uses an Arduino Uno header connection, so can be easily used with other boards. The ST8034ATDT can be easily used by any STM32 MCU that has built-in smartcard support, the QR scanner interfaces via UART, so will work with anything...

There a few changes to drastically simplify the design and optimize it for low-cost, short-run production via fabs like PCBWay and also make hand-assembly more practical. (Smaller PCB, large solder pads and track spacing, larger minimum hole size, 2 layer not 4, SOC-16 interface IC as opposed to QFN-24, remove battery and charger) This worked out well, with this board coming in at about $20 USD per board for a batch of 5 and ~15 USD for a batch of 10, once you account for shipping, import duty, etc. (Less than 1/3 the cost of the original shield that you can see and order here: https://www.pcbway.com/project/shareproject/Specter_Shield_v1_0_0_2024_Update_ea6f25c5.html)

You will need to provide your own QR Scanner module, GROW GM65 or GM805, though GM65 works better with Binary QR codes at the moment. You need to provide your own smartcards. the J3H145 is your best bet to run the Specter Java applets. You can provide your own power solution via the VIN, 6-9v DC (AAA batteries fit nicely between the shield and the dev board). You can find a 3d printed case linked below.

Original assembly order number was T-1N16W685030A (So this should allow PCBWay to make sure that the correct BOM is used as well as find the answer to the engineering questions they asked along the way)

For the PCB, I have also found that a 1.2mm board works the best in terms of fitting in existing cases, though a 1.6mm board is fine too.

The main things to check that may come as questions from PCBWay during fabrication are the orientation of the square buzzer and the ST8034ATDT. Both can be clearly seen in the photos attached to this project.