Juhana Helovuo wrote:
Thanks for your supportive comments. I think I was a
bit unclear on
some points, so you misunderstood some details.
I just have a few different design ideas. :)
seem to let go of the thought that I would prefer a tester
device to be connected directly to the internet
That would be another design strategy.
However, I wanted to make the tester device to be just
interface between USB and the target mainboard. That makes it
easier to design and fabricate with hobbyist methods and budget.
Yes indeed! I think both approaches are equally useful. Some will
prefer to buy a device, and some, who have the ability, may prefer
to build their own.
A design constraint for me is e.g. using only
components that I can
solder into a self-designed, self-made PCB. Using small pitch SMD
devices or a components requiring reflow soldering seems a bit too
much right now.
I understand. One thing that makes this design constraint a bit
tricky is that everyone has different equipment and ability here, but
I agree that no smaller than SO components would make the build very
Also the tester device firmware will be simpler this
Even if the device is doing a bit more the task is pretty simple, so
firmware would in any case be manageable I think.
I discovered that flashrom utility alone is quite a
Ok. I haven't followed it for a good while.
Flash emulator would be nice, but emulating a SPI
flash ROM would
require single clock cycle response times for ordinary read
commands. There is very little time for the ROM from receiving the
last address bit to start transmitting the data.
Yep, an emulator should be SRAM backed.
I do not have a document at hand, but I recall that
for the AMD
SB7x0 this should be done at 16...33 MHz clock rate. Some SPI
controllers could do it even faster, since many ROM chips are rated
to operate up to 60 MHz or more.
I think in practise not much more than 16MHz is used, even though
some chips go up to 75 or 90.
ATmega U chips
I am currently working with AT90USB162.
All right. With QFP on the table there's suddenly a whole lot more
possibilities for the design.
The choice was also influenced by easy availability
and ease of
Right. I've understood that Atmel are having some difficulties
shipping the U series.
> One problem with FETs is that they must be plugged
in to the
> mainboard the right way.
simpler to use .. if it had a solid state switch
The FET switch device I am using is this:
I believe it should work with the terminals plugged either way
around. It should also work regardless of the voltage used in the
mainboard switch sensing pins. E.g. in my test mainbaord the reset
and atx power switch pins have different operating voltages (5V and
A switch like that should indeed work perfectly, and the price is
right. Sorry, I was thinking of a discrete FET.
Do you know where these units can be purchased, with the various
voltage ratings and power plugs that are needed around the world?
I haven't tried internationally. In Finland, Jimm's PC claims to
have them in stock a total of 4 pcs.
No idea about different plug types, but I believe this one would
work at least in Finland, Sweden, and Germany.
Since coreboot is very much an international project I think we'll
have to spend some effort on supporting various types of these power
we will simply
implement the serprog protocol properly using
native USB concepts. It should be very easy.
Yes, communication from flashrom program to SPI ROM should go over
native USB, no serial emulation needed.
Let's look at designing that protocol. Are you on IRC?
I used serial port only for testing that I can
actually talk to the
SPI ROM from the microcontroller.
The test setup was based on Arduino Uno, which can do
Actually the Uno has an ATmega U for the USB interface, with firmware
released, specifically so that it can be reprogrammed with different
descriptors and make better use of USB. It requires a standalone AVR
programmer though, and is beyond the level of many Arduino users, so
it hasn't really taken off..
OK, so.. Do you like svn or git? Let's set up a repository or two
for this work.