Jim Paris wrote:
Pelle Windestam wrote:
I did some more testing and it appears that it doesn't work with the
unmodified FTDI eeprom either as I stated in my first e-mail. In
both cases I need to use /dev/ttyUSBx access first to get
libftdi-access working.
If you want to really dive in deep, you can modprobe the usbmon
module, use wireshark to get a full dump of the bus traffic, and
compare the two cases to see what might be missing in the libftdi-only
case.
-jim
I did some logging with usbmon yesterday, and I have tried to make some
sense of it. I have never looked at usb bus traffic before, so it is
slightly confusing. What I could make out of it however is that in the
working scenario, I can see the frames I send out and the response from
my external device.
In the non-working case I can see the data going out as a "URB_BULK out"
package, and in most cases I receive a "URB_BULK in" packet with the
same data as I sent out, usually split over several packages (I get this
package in the working case as well), but never a response from the
external device.
I have looked at the output signals from the FTDI chip with a scope, and
on the TX-line I can only see a single blip in the non-working scenario.
In the working scenario the traffic is there as expected.
//Pelle
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