Shopping list for Specter-DIY

Here we describe what to buy, and in we explain how to put it together and a few notes about the board - power jumpers, USB ports etc.

Discovery board

Main part of the device is the developer board:

  • STM32F469I-DISCO developer board (i.e. from Mouser or Digikey)
  • MiniUSB cable
  • Standard MicroUSB cable to communicate over USB

Optional but recommended: - Waveshare QR code scanner with long pin headers like these or these to connect the scanner to the board (4 pin headers needed).

Check out the assembly video on youtube

We are currently working on an extension board that includes a smartcard slot, QR code scanner, battery and a 3d printed case, but it doesn't include the main part — discovery board that you need to order separately. This way supply chain attack is still not an issue as the security-critical components are bought from random electronic store.

You can start using Specter even without any extra components, but you will be able to communicate with it over USB or the built-in SD card slot. Using Specter over USB means it is not airgapped so you lose an important security property.

QR scanner

For QR code scanner you have several options.

Option 1. Recommended. Resonably good scanner from Waveshare (40$)

Waveshare scanner - you will need to find a way how to mount it nicely, maybe use some kind of Arduino Prototype shield and some ducktape. For wiring see

No soldering required, but if you have soldering skills you can make the wallet way nicer ;)

Option 2. Very nice scanner from Mikroe but pretty expensive (150$):

Barcode Click + Adapter

Option 3. Any other QR scanner

You can find some cheap scanners in China. Their quality is often not that great, but you can take a chance. Maybe even ESPcamera would do the job. You only need to connect power, UART (pins D0 and D1), and trigger to D5.

Option 4. No scanner.

Then you can only use Specter with USB / SD Card.

Unless you build your own communication module that uses something else instead of QR codes - audiomodem, bluetooth or whatever else. As soon as it can be triggered and send the data over serial you can do whatever you want.

Optional components

If you add a tiny powerbank or a battery & power charger/booster, your wallet becomes completely self-contained ;)