[Arm-netbook] MicroSD JTAG programmer

[Henrik Nordström]

sön 2012-12-16 klockan 16:42 +0000 skrev luke.leighton:

>  there's something based on the FT2322 but i'm not seeing a place
> where it's actually sold.

What you use is

1. A microsd breakout card, giving you access to the wires.

2. A standard JTAG programmer.

3a. Suitable dupont wires connecting the two. Which type to use depends
on the uSD breakout card you are using. The card sold by Tom have 2.0mm
spacing in it's JTAG connector.

3b. Suitable premade cable connecting your JTAG adapter to the microsd
breakout board.

Or you go hunting for the signals on the board, and connect wires there
to a pin header matching your JTAG adapter, like I have done on two of
mine boards

In your case the uSD connector have the signals easily accessible. Just
solder wires there and wire them up to a suitable pin header. It's only
some minutes to get it done.

But uSD JTAG is not entirely trivial on A10. It is not something you use
to try to diagnose why a board is not working. Even if the CPU reset
state have the port configred for JTAG BROM immediately reconfigures the
port for SD booting. You need to boot the CPU into a state where PF is
configured for JTAG. The  methods I know are

a) FEL boot mode. (note, there is automatic fallback to FEL mode if
other boot methods fail even if FEL/usbboot pin is not active)

b) Flashed with boot loader where JTAG is enabled (and SDC0 disabled)

c) SD booting code that configures PF for JTAG and then loops, waiting
for you to take over with JTAG.

d) Halt at u-boot prompt an manually reprogram the port for jTAG access
using mw.l command writing directly to the relevant PIO register.


Regards
Henrik