On Fri, Aug 08, 2008 at 02:15:39PM +0300, Martin-Éric Racine wrote:
In conjunction with item #2 above, we are hereby giving the Coreboot community an opportunity to influence the design of this new product.
I have a few thoughts, in order of importance they are:
* By far the most important one: Use a more intelligent USB chip
USB can do 480Mbps so transfering half a megabyte should not need to take several seconds. There is obviously a huge opportunity for improvement here, and as it happens this is also the main bottleneck in the dongle when doing intensive development.
The most elegant solution is to implement USB completely in the FPGA, but a separate chip is likely more economical. Key point is that it must not be a dumb serial chip.
Cypress had the EZ-USB SX2 (not FX2) but unfortunately it's EOL.
The PLX NET2270/NET2272 are really powerful, but may be a bit costly.
NEC µPD720122 is another option, it's on par with the Netchip.
NXP ISP1582 may be the winner. Unit price/2k is 2.87 USD.
Finally it's of course also possible to implement part of USB in the FPGA and only use an external transceiver chip. There are plenty of those chips available.
* Use an Actel FPGA that is live from power on
This allows the dongle to be powered comfortably from the target without compromising usability.
* Automatic power switch with a few protection diodes
Get rid of the power switch jumper.
* Replace any other jumpers with toggle switches
Ideally remove hardware configuration completely and do all settings via USB.
* SMD LEDs
Because the through hole ones often get bent out of shape when the dongle is carried in a bag.
//Peter