Thanks for the suggestion about checking for stalls - while I'm not
sure it's fixed the problem (you know how these "sometimes works
sometimes not" problems are) it does seem to have made the code more
stable.
On Oct 10, 2005, at 11:45 AM, David Ferguson wrote:
At 9:59 AM -0400 10/10/05, Michael Heinz wrote:
Question:
Is there a way I can replace the usleep calls with some function
that can check to see if the calculator is in a ready-to-send or
ready-to-receive state? I'm guessing that the control pipe might
be good for this, but I can't find any documentation on how to use
the control pipe at all.
Any suggestions?
If it looks like an RS-232 interface on the calculator -- does it
send you any kind of flow control (X-ON/X-OFF)?
You communicate with the control pipe (endpoint 0) using
DeviceRequest(). Standard device requests are defined in Chapter 9
of the USB spec (available from http://usb.org).
Perhaps checking the endpoint status of the data pipes would tell
you if they were stalled. Normally I would expect a device to
either NAK or STALL requests if it was busy processing them.
Hope this helps.
David Ferguson
Apple Computer
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