Hi,
I have tried to make a user-level driver for a home-grown device,
interfaced with a serial port. Unfortunately, I couldn't make it answer
fast, even if the line is set to 38400 bps. I use termios structures with
O_NOBLOCK and select() to get the answer received, but there is a delay of
20ms after the character available on the serial port (as I could measure
in an oscilloscope).
There is a simple way to program a tiny protocol for doing half-duplex
comunication with a faster response than this? I'm aware of RTlinux
(real-time), but I'm looking for a simpler way. It seems that the problem
is a task-switch when I try to read back the result.
Perhaps another line discipline could do the job, if I make the protocol
in the device driver.
Any pointers to such drivers? Other suggestions?
regards,
Rildo
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|\ FPGA and uController Rildo Pragana \
\ \ Design & Implementation PO Box 7440 Recife \
\ \ System Software * Linux Brazil 50,630-970 \
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