On 7/4/2011 7:54 PM, Uwe Bonnes wrote:
"Alex" == Alex Stefan<alexandru.stefan@xxxxxxxxxxx> writes:
...
Alex> I have talked to the developers of FTDI lipspi and they said that
Alex> their current version only supports MPSSE SPI, not bit-banging.
Perhaps of bad performance?
Well, the developer said nothing about this, but it could well be a
possibility. They have asked me to add the CBUS SPI bitbang feature into
their library after I'm finished so I don't think they are aware of the
big performance problems.
Alex> Could you please offer some more details on the USB timing?
Google "usb frame" offers me (german) explanations on:
http://de.wikipedia.org/wiki/Universal_Serial_Bus
I should have been more specific. I was refering to ideas on how I can
improve the USB timing.
Alex> How
Alex> can I set the interval between 2 USB frames (from 1ms to 125 uS) ?
Supposed you run on linux or a similar system:
strace -ttt -f -o<logfile> <your_program>
Thank you very much. I will try it in the morning. From what I saw in
the Linux kernel, a call to ftdi_set_bitmode has the following 'trace':
ftdi_set_bitmode -> usb_control_msg -> USB Request Block sent to device.
Alex
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