[Cryptech Tech] FMC Arbiter

[Павел Шатов]

On 30.08.2015 23:40, Fredrik Thulin wrote:
>>> 3) My Novena somehow doesn't work properly, when bridge board is powered
>>> from it. I removed diode D2 and added solder bridge instead to power my
>>> bridge board from wall Micro-USB phone charger.
>>
>> Interesting. I don't remember ever seeing any power ratings for the 5V rail
>> from the Novena, but we're not consuming very much at all with the
>> dev-bridge board IMO.
>
> It seems my Novena wouldn't boot while powering the dev-bridge (fmc-test
> program already in the MCU), but I suspect some other issue than power
> consumption because my Novena won't boot with the dev-bridge attached and
> running from an external power source either (I just cut the Novena 5V input
> pin on D2).
>
> The only way I've managed to get it up and running is by booting the Novena,
> loading the FMC bitstream you provided and *then* powering up the dev-bridge
> board.
>
> It is as if some condition of high/low pins on the pins of the connector will
> prevent the A9 on the Novena from booting. How could that be? I thought only
> the Spartan-6 on the Novena was connected to the connector we plug into.
>

Yes, I have similar problem! I use STM32F429-DISCO board to program my 
dev-bridge. It has two jumpers, that switch it into ST-LINK mode. My 
Novena won't boot, when this programming board is powered. To start my 
Novena, I disconnect USB cable from the DISCO board, power up Novena, 
and then re-connect DISCO board. I don't understand, what prevents 
Novena from booting, when ST-LINK interface is powered.

>>> Demo program for STM32 keeps writing "random" stuff in FPGA, reading it
>>> back and comparing. As long as everything is fine, green LED should be
>>> on and yellow LED will blink after every batch of tests. In case of
>>> readback mismatch, red LED will be turned on.
>
> I haven't seen the red light at all yet, but the status indicated by the
> steady green + blinking yellow is a bit unclear to me. That seems to be what
> happens both with the Novena FMC bitstream running, but also with the dev-
> bridge unconnected? Just a slightly different frequency?

Hmmm, the green light is turned on at the very beginning, the yellow 
light toggles after every 100000 rounds of testing or so. It blinks to 
indicate, that the board is alive and doing something. The red light 
should be turned on as soon as mismatch in read back data is detected. 
When dev-bridge is unconnected, the red light should be turned on 
immediately. I will investigate.

--
With best regards,
Pavel Shatov