[Cryptech Tech] Tamper detection

[Pavel Shatov]

On 19.07.2016 11:54, Fredrik Thulin wrote:
> On tisdag 19 juli 2016 kl. 10:04:31 CEST Jakob Schlyter wrote:
>> Richard Lamb has offered to help out with tamper detection and the plan
>> we have come up with is that he will create a small tamper daughterboard
>> that connects to the 10-pin tamper GPIO on the alpha board, along with
>> some updated code for the AVR. Once we have more experience with the
>> tamper circuits, we can fold the components into the main board.
>>
>> For this to be really usable, we need a battery on the alpha board. This
>> can be implemented by adding a battery holder to the next rev
>> and/or adding an external battery to rev03. Rick suggested that we might
>> want to use a larger battery in combination with a supercapacitor so the
>> battery can be replaced without loosing the MKM.
>
> The next revision (rev04) ought to fix the current leakage from the VBAT to
> the 3V3 rail, but after some more thinking I think maybe the tamper
> daughterboard can have the battery connector/super-cap. That way the
> daughterboard will be usable with the current rev03's too.
>
> Stated differently, the tamper daughterboard could feed the VBAT on the Alpha
> instead of being fed by the VBAT on the Alpha.
>

I think, that prototyping on a daughterboard and then merging tested 
schematics with the primary Alpha board is the best way forward.

Do I get it right, that you suggest doing a daughterboard for rev.03 
with a battery holder, and then merging it with the base board, so that 
rev.04 will have a proven battery circuit?


-- 
With best regards,
Pavel Shatov