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Re: Closing/disabling a device
Le 12/12/2011 16:14, Frank Pagliughi a écrit :
Hey All,
I'm looking to interface a serial GPS unit to an Atmel AT91 using
eCos. GPS units constantly stream out data at 4800 baud, but I
actually only need to get data from the unit once every few hours to
check time and position. The idea is to have a thread wake up, read
the data, then go back to sleep. The code (ported from Linux) uses the
stdio FILE input routines (fopen, fgetc, etc)
But the data arriving consistently from the GPS is filling up the
buffer in the AT91 serial driver and I can't figure out how to empty
or clear it. I tried CYG_IO_GET_CONFIG_SERIAL_INPUT_FLUSH, and also to
just close the port (fclose) while the thread is sleeping.
I have started looking at the driver to see if the ability to
flush/drain the buffers is implemented, but I think I would prefer the
second option - closing down the driver to disable interrupts for that
serial port while it's not needed.
I don't see a low-level mechanism to do this. Am I missing something?
Is there low-level code that trickles down to a driver when an
application calls close() or fclose() on a device?
I have the same problem (not for one for a single serial port but 4 of
them plus many other peripherals). eCos starts all the drivers it knows
as soon as it boots. It seems that the solution would be to implement
CYGPKG_POWER in the concerned drivers, however I wonder how one could do
it in a clean way when the UART is the generic 16x5x serial driver
(dunno if AT91 has such a driver) since power control is specific to
each MCU/CPU family. The quick and ugly solution is to hack the UART
registers from the application when the driver has to be silenced and to
restore them later when needed. The CYGPKG_POWER package is available
but AFAIK there is no example of an implementation in the public eCos
repository.
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