>
> Hi All
> You might recall my laptop parallel port had a problem communicaing
> with the OOPic. I got all the parts and built the active cable from
the
> files section that Dennis suggested (thanks Dennis) and I can now
> detect it. So I tried a very simple flashing led project.
Everything
> looks like it's working and the IDE says it downloads - the
progress
> bar shows it downloading - etc but the project didn't work. When I
read
> the data back up from the eeprom there's nothing there. I know
there's
> power on the board because I can ground an led in the prototyping
area
> and it lights up. I'm going to just buy another OOPic I think but
does
> anyone have any advice before I do? Also I'd like to get Dennis'
book
> but here in Australia it's out of print and the only ones I can see
at
> Amazon don't deliver here for some reason. Any clues?
>
There's one other 'gotcha' to parallel programming: you MAY have to
remove the programming cable to get the program to run. If you want
to do debugging, you need to plug the cable in to the other I2C
connector.
But that doesn't explain why you can't read the EEPROM. The problem
is that it is almost impossible to troubleshoot I2C without a logic
analyzer. You can certainly see part of the operation with an
oscilloscope but to really capture the traffic requires a logic
analyzer.
Sometimes it is possible to get an clue about the signals with a
logic probe like http://www.pololu.com/catalog/product/314
At least
you can see/hear if the signals are toggling. There are a number of
logic probes on eBay.
At idle, both the clock and data lines should be high, A transfer
starts when the data line goes low while the clock line is still high.
Richard
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