[Elphel-support] 10373 power up OK (from Elphel Development Blog)

[Andrey Filippov]

(text-only version of the Elphel Development Blog posting -
http://blogs.elphel.com/2009/10/10373-power-up-ok )

So far - so good, after installing most of the components I tried to power
up the board. No smoke, power supply voltages (at least those that do not
need software to be turned on) seem to be correct, none of the components
are hot.

Next step was to connect USB cable to the programming port - there is a
cp2103 bridge chip on the board that is connected to the serial port on
TMS230DM6467 - port that can be used to boot the system while the flash
memory is empty.

When I just started design with this Texas Instruments chip the datasheet
was showing network boot mode (similar to Axis ETRAX we used in all our
previous cameras) but later that mode disappeared from the documentation
(probably TI ran out of the ROM space) so we had to use another way to
program the system so it would be both
 * safe from "bricking" caused by interruption of the firmware update
process (or just plain software bug - our products are designed for
development, so bugs are likely) and
 * the firmware installation/upgrade would not require any special hardware
connections, especially those that require opening the camera case.

The USB connection seemed nice - it is commonly used for the firmware
installation, uses regular cables and the port can be used as a
system/debugging console during normal operation.

I selected a small (5mm x 5mm) Silicon Labs CP2103 converter as it has
additional general purpose I/O pins that can be used to switch between boot
modes and generate reset signal for the CPU. This chip seemed to be widely
used and to have standard Linux drivers. I was not so sure about those extra
GPIO pins support, but noticed that Silicon Labs have some mention of the
Linux software, so I've purchased their evaluation board to be able to
experiment with that software without doing it on an actual board. But I
never tried it until the time came to connect the 10373 board. So I opened
the evaluation board box, connected it to a computer and - noticed, that
there is no support for the extra pins in the regular driver that I've got
with Ubuntu 9.10. And the driver provided by the manufacturer did not
compile with the kernel I've got. So I had to spend half of the day figuring
out how those drivers work and how to make one that will work on my
computer.

That combined driver (I ported only GPIO control from Silicon Labs driver to
the one provided with the system) eventually worked and I was able to turn
on/off four LEDs on the evaluation board. It required some guesswork and
testing as I could not find any documentation on the internal registers and
which bits control setting of the GPIO pins - only their API description
that assumes usage of some binary-only *.DLL files that may probably work
with WINE.

Anyway - I have now a working solution - modified driver and a small
application that issues ioctl calls to control GPIO pins. That part also
seems to work with 10373, but that is as far as I could go before actually
coding for the new processor. And that promises to bring a lot of fun :-)

Andrey
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