Atari SIO madness


sixtyfifthbit

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Aug 24, 2007
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I just got Peca's TinyBOB and USB cover, and with WizardStan's EXT jacks, I can now attempt with the Pandora what I couldn't with the GP2X: A direct connection between my old Atari (actually Indus GT) disk drive and the OpenPandora. After seeing other posts regarding the EXT port, I figured the connections would go something like this:


Pantari.png



The reason I couldn't do this on the GP2X is that I need both a RX/TX pair AND another output for the Command line (high to trigger a command) which I can do here with any of a number of lines, but likely the RTS or CTS line.


Some questions:


[1] Should I use the UART2 or UART3 lines? It looks like I should use the UART2 lines, especially because [A] The RTS/CTS lines look like they're with UART2 and Kernel comms seem to run via UART3. But is UART2 ready to use in software/firmware?





[2] Is there a steady 1.8V reference from the Pandora? Can holding a line high provide a reference if the 1.5/3.0V line cannot?






Thanks, and I'll keep you posted on the progress!
 
UART2 pins won't be functional as UART until you patch the kernel, or update it to 2.6.37+. But looking at your diagram, it looks like it won't be doing standard serial anyway, as the command line has different meaning compared to RTS/CTS?


If you are going to do GPIO bitbanging it doesn't really matter how you connect those lines.
 
Thanks, and I'll keep you posted on the progress!
Make sure you do that. I don't know what you're trying to accomplish exactly, but it sounds neat! :)


Notaz has been very helpful in this topic. I think holding 1 line high as a 1.8V reference will work, but I would like confirmation on this as well (if only just out of interest).
 
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UART2 pins won't be functional as UART until you patch the kernel, or update it to 2.6.37+. But looking at your diagram, it looks like it won't be doing standard serial anyway, as the command line has different meaning compared to RTS/CTS?


If you are going to do GPIO bitbanging it doesn't really matter how you connect those lines.

Actually the TX/RX are effectively standard serial lines. I'd need to raise RTS/CTS manually, but I'd rather not have to implement RS-232/UART mechanics myself.
 
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