I am developing a hardware-software project involving usage of 1-wire bus from DalSemi. I use selfmade DS9097 passive 1wire adaptor and i have a problem - Pegasos-II can't boot up with the adaptor is plugged into its serial port.
The adaptor internals are described here (i used the first schematic):
http://owfs.org/index.php?page=com-ds9097-passive
The machine behaves like it's stuck on some very early stage. Even HDD LED doesn't go off (this means even IDE reset is not deasserted). I have to unplug the adaptor in order to boot up the machine and plug it back after it. This is: a) annoying and b) would prevent Pegasos (probably EFIKA too?) usage in production run.
Can this problem be worked around? I guess this happens because Pegasos says something into serial port, unexpectedly gets it back and crashes. Is there a way to disable that failing test on the serial port ?
Another way to solve this would be adding PCI add-on card with a serial port, but i don't have one.

No...

Unfortunately the serial port is used for early debug and as a failsafe if anything dies like PS/2 keyboard/mouse or display. The system requires some kind of input/output console to be present for user intervention (even if it is on serial and simply not connected, and the system is set to autoboot, the serial port has to be there).

If you're looking to do something like this you'd probably need to get the Pegasos or Efika with a custom firmware which did not attempt to use the serial port in the way it's using it, however this begs the question of how you control the system if the serial port is not used. Can you rely on graphics etc?

Developing the project for Efika, would probably be better done if you used the internal IrDA connector attached to PSC6 - it has the 3 data pins you need (actually you will maybe need to drive it manually using GPIO and mimic DTR) plus ground. It is not RS232 but you are making your own circuit so this doesn't really matter.

For the Pegasos.. I am not sure how you would want to prototype it in this instance. You may be able to configure the VT8231 to support the IrDA pins in the front panel header to act as a serial port (check the VT8231 docs they're off Google) and see if you can drive it. At least then you get a 1-wire interface that can be connected to a 3-wire serial port header with the same pin format on both devices..

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Matt Sealey

Hello Matt! Thanks for the answer, nice to talk to you again.
GPIO-based approach would not do because 1wire requires precise timings and UART is (ab)used to generate them in case of RS232 adaptor.
As to IrDA pins of VT8231, thanks, it's an interesting thing to research... If i ever get time... Anyway these pins are just floating around because the dongle to connect to them is almost impossible to find (noone even knows what it looks like).
I mentioned EFIKA just because of its existance, i will not tie up my project to it, i wanted just to point you at the potential problem. The project is a video surveillance, access control and security system, and the production installation will use a PC running Linux (it's possible to obtain used Pentium-III desktop for free; it has more than enough CPU power for this task).
I use Pegasos as a development machine (because i still own it and i still like it).
The SW part will be opensourced as soon as something working is ready, BTW. If someone is interested... This probably even could count for "EFIKA project".