[Arm-netbook] A10 EOMA-68 CPU Card Schematics completed

Henrik Nordström henrik at henriknordstrom.net
Fri Sep 7 19:07:20 BST 2012

> there's been only one omission that i've noticed, and that was that
> the JTAG selection wasn't wired to a jumper selector (however: u-boot
> is), so for this 1st revision it will be necessary to use the DIL2-44
> JTAG pins rather than being able to use those "Universal SD Debugging"
> cards.  sorry!

That's no problem and can be worked around in software, unless I
completely misunderstand what the JTAG select pins does. Normally the
JTAG select pins are not used for SD JTAG debugging, instead you
activate the JTAG port by software.

We have a small SD image which switches the port to JTAG and then loops
infinitely, allowing you to switch from SD card to JTAG probe and
continue debugging early bootloaders.  See jtag-loop in sunxi-tools,
available as both source and binary.

If you want to JTAG the kernel then a little command in u-boot can do
the same, combined with a script.bin which do not enable MMC0.

For debugging SD boot process you want to use the other JTAG port
anyway, so nothing lost there.

> we have an extraordinarily tight schedule to meet for getting the
> first I/O Board out (a 14in Laptop.  yes.  several complete working
> prototypes, by 10th october).  if anybody would like to help
> accelerate this process by placing an order directly with the ODM
> house for a laptop to be made up, please do let me know and we can
> arrange something.  i know there's been several people who've
> expressed interest.

I certainly have interest, but not in a panic.


More information about the arm-netbook mailing list