[coreboot] brainstorm: new LPC dongle from Artec Group
peter at stuge.se
Fri Aug 8 14:11:05 CEST 2008
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
* SMD LEDs
Because the through hole ones often get bent out of shape when the
dongle is carried in a bag.
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