Firmware for functional-level testing of completed BitSafe (a hardware Bitcoin
wallet) development boards.



Expected outcomes:

USB connection: the DUT should power up and enumerate as a USB HID device when
plugged into a USB host.

RGB LEDs: should flash in a RGB sequence when the DUT is powered up. Each LED
should be on for about 0.25 s. The sequence will speed up whenever there is
USB activity.

Pushbuttons: the pushbuttons can be used to cycle through the tests. The
button on the right will advance to the next test, while the button on the
left will go back to the previous test. If the DUT does not respond to
pushbutton presses, then it is likely that there is an issue with one of
the pushbuttons.

SSD1306-based OLED display: should display something. Since the hardware
interface is write-only, the only indication of failure is nothing appearing
on the display.

External memory (SST25VF080B): the JEDEC ID of the chip will be queried. For
the SST25VF080B, this should be bf258e (according to the datasheet). The
firmware will also perform an erase-program-read cycle on the first 4K sector
of the external memory, and should report "pass" if everything went as
expected. Erase and program failures are indicated by "erase failed" and
"verify failed" respectively.

Atmel CryptoAuthentication (ATSHA204): should wake up (indicated by "Wake
test: pass") and display the first 12 bytes of the output of a sample of the
internal hardware random number generator. Note that if the ATSHA204 is
in an unlocked state, then as per its datasheet, the random number generator
will return ffff0000ffff0000ffff0000. If "Wake test: fail" or "Random: error"
appears, there is probably some sort of communication error (likely related
to timing).

Hardware noise source: should display the mean and RMS amplitude of the noise
source. The mean should be near 1650 mV. The RMS amplitude depends on the
noise source used. For thermal noise, this should be near 135 mV. If the
RMS amplitude is huge (> 1000 mV) or tiny (< 10 mV), then something is
definitely wrong with the noise source.