FPGA Central

Hey, does anybody know if you can damage Atmel's newer FPGAs with a
bad bitstream (ie vdd-to-ground contention)?

There's no Big Scary Warning in the data sheet (that I could find),
but on the other hand, given the fact that so much of the global
routing is based on pass transistors and they let you create
multi-driver buses, I can't see how they could possibly protect
against this.

This was kind of weird. I know Xilinx has put the Big Scary Warning
on datasheets for parts which actually can't be damaged this way
(covering their ass?), so I'd expect most vendors to err on the side
of caution. Hrm.

Anybody know?

- a

--
"I didn't see it then, but it turned out that getting fired was the
best thing that could have ever happened to me. The heaviness of
being successful was replaced by the lightness of being a beginner
again, less sure about everything. It freed me to enter one of the
most creative periods of my life."

-- Steve Jobs, commencement speech at Stanford, June 2005

Just to clarify:
A wrong FPGA bitstream can create massive internal contention, which
can damage a part. (I have seen a puff of smoke coming out of a totally
misconfigured XC3042 15 years ago...)
Xilinx has had CRC protection since XC4000, > 12 years ago. CRC
protects against accidental errors, but does not protect against
feeding a legitimate bitstream, meant for one part type, into the wrong
part type.
To protect against this, the Xilinx bitstream also checks the chip ID.
We have not heard about any problems ever since.
Peter Alfke

"Peter Alfke" <[email protected]> writes:
> A wrong FPGA bitstream can create massive internal contention, which

This is not ALWAYS true. It was untrue for the XC6200 sieres:

http://www.fpga-faq.org/archives/10625.html#10627

But that post (which I just found) explains *why*, and I know that the
Atmel chips don't share the same feature (single source per wire).

- a

Adam Megacz wrote:

> Hey, does anybody know if you can damage Atmel's newer FPGAs with a
> bad bitstream (ie vdd-to-ground contention)?

The same question: is it possible to damage a Cyclone with a bad bitstream?
Remark: it's a feature, not a bug. SRAM-based FPGA devices are too easy
to clone. FPGA manufacturers: why can't you mount two chips inside one
package,
one containing an FPGA and the second one with configuration flash and add
readback fuses, JTAG access fuses etc.? A small amount of EEPROM would
be great too...

Best regards
Piotr Wyderski

Lattice XP? One die is much better than two.

Cheers,
Jon

Jon Beniston wrote:

> Lattice XP?

Or Actel ProASIC. But what about Altera and Xilinx? :-)

> One die is much better than two.

Sure, but I've been told that it is hard to produce flash and FPGA cores
on a single piece of silicon because of technological differences.

Best regards
Piotr Wyderski

"Piotr Wyderski" <[email protected]> skrev i meddelandet
news:d990fp$a3g$[email protected]..
> Adam Megacz wrote:
>
>> Hey, does anybody know if you can damage Atmel's newer FPGAs with a
>> bad bitstream (ie vdd-to-ground contention)?
>
> The same question: is it possible to damage a Cyclone with a bad
> bitstream?
> Remark: it's a feature, not a bug. SRAM-based FPGA devices are too easy
> to clone. FPGA manufacturers: why can't you mount two chips inside one
> package,
> one containing an FPGA and the second one with configuration flash and add
> readback fuses, JTAG access fuses etc.? A small amount of EEPROM would
> be great too...
>
> Best regards
> Piotr Wyderski
>

AT94Sxx Secure FPSLIC?


--
A. P. Richelieu

"Ulf Samuelsson" <[email protected]> writes:
>>> Hey, does anybody know if you can damage Atmel's newer FPGAs with a
>>> bad bitstream (ie vdd-to-ground contention)?

> AT94Sxx Secure FPSLIC?

Sure; I'm working mainly with the AT94xx, which is just an AT94Sxx
without the EEPROM. Which, in turn, is just an AT40xx plus the AVR
microcontroller. Atmel hasn't really changed their fabric since '98.

- a

--
"I didn't see it then, but it turned out that getting fired was the
best thing that could have ever happened to me. The heaviness of
being successful was replaced by the lightness of being a beginner
again, less sure about everything. It freed me to enter one of the
most creative periods of my life."

-- Steve Jobs, commencement speech at Stanford, June 2005