[Gnuk-users] Failure mode of FST-01

[NIIBE Yutaka]

Hello,

During preparation of NeuG on FST-01 devices (for shop.fsf.org), I
encountered a problem:

     FST-01 w/ tube from Seeed Technology doesn't work at all.

In these three years, I have experience to access ~200 pieces of
FST-01.  This was the first experience for me to see bricked FST-01
from the beginning.

I removed the tube and I tried to access MCU by connecting ST-Link/V2.
SWD connection worked and it was possible for me to unlock the flash
protection and to update flash ROM of MCU to be Gnuk 1.1.9.  But it
didn't work, either.

I intentionally made Gnuk without flash protection and observed what's
going on by OpenOCD + GDB.  It looped at the initialization of clock.
The external oscillator didn't work at all.

Today, I put soldering iron to the XTAL and let the solder under XTAL
flow.  Then, the FST-01 is back and works well again as Gnuk Token.
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