January 7, 2010
about a month ago
how does the ATMEGA328 form a “trusted” processor? how would it even be used being as only the i2c is connected to the beagle?
What is the ATMEGA328 used for on the board? It seems to be attached only to the headers on the cape with the exception of being connected to I2C2.
News - New Product Friday: New P…
about 8 months ago
How much is that doggy in the window?
The one with the waggy tail.
How much is that doggy in the window?
I do hope that doggie’s for sale.
Link to the product page please…..
about 10 months ago
Might you consider changing out the DS3231MZ/V+ part for at least the DS3231M+ if not the DS3231 ? Presently the board uses the cheap MEMS part rather than a decent Xtal based version and the 8pin package simply lacks the thermal mass for best stability. While the DS3231MZ/V+ is still MEMS based rather than Xtal based moving to either part in a 16pin package helps accuracy and stability. Also placing a ground plane on the topside of the board under the DS3231* can be helpful. So long as it’s connected to a larger ground pour on the board this also serves to increase thermal mass thus decreasing thermal drift while also isolating the chip from other signals that may run underneath (as noted in the datasheet). Basically I figure if you’re going to include a RTC, the RTC ought be as good as is practical. Moving to the DS3231M+ is a step in the right direction but we can do better without much increased cost. This because in some applications of this cape accuracy in timing could become quite important. (thinking about applications in trusted time stamping and digital signatures where one need prove that events happened at specified times or in a specified sequence)
Do the individual IC’s each have their own ECCN? Can the individual IC’s be exported by themselves? If so that should do 2 things. First it ought to make getting an ECCN for the board easier, and second one could conceivably export all the individual components and build the boards elsewhere until the ECCN for the board is in place. Gotta love Govt. rules and policy.
This looks configured as a top cape. Any way to get one either without headers or configured with stacking headers?
I guess a solder bridge across the entirety of a 3 way solder jumper could short I2C1 & I2C2 together given poor soldering but a physical header jumper ought make that difficult with the bus to the board being the center and the beagle header being one side or the other. note though, per the beagle srm the cape eeprom needs to stay on I2C2.
I just mean moving all the crypto chips on the cape as one between i2c1 and i2c2 such that the cape crypto functions as a whole can be moved to either i2c bus. personally I think this is an option that ALL I2C based capes ought incorporate. I get now that this board is not intended as a crypto accelerator. some good examples of what and how it might be used in the description would be good though. (give it a minute or so & you’ll see what I’m thinking.)
Looks like a great board for it’s intended use. The bus select option involves adding 2 more 3 way solder jumpers and took less than 5 minutes to add and place in eagle (yea sparkfun for making those available!) Heck, I’ll send ya the revised board files.
ok, the data interface for all these chips sits in the i2c bus, so it looks like for much real encryption work this cape will be really slow, bottle necked and constrained by the chosen bus and it’s bandwidth. I might also suggest for a rev 2 adding a set of 3 way jumpers such that it can sit on either i2c1 or i2c2. the inclusion of solder jumpers for pullups or not on the i2c bus was a good choice. I also fail to see what this cape does or assists with that the AM3358/AM3359 does not already do with it’s on board cryptographic abilities which do at a minimum AES, SHA, & MD5, and possibly others.
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