[U-Boot-Users] How To Register Interrupt Routines in ARM920T?
wd at denx.de
Wed Dec 8 10:10:55 CET 2004
In message <698a2fda0412072241b442444 at mail.gmail.com> you wrote:
> I am porting U-Boot to a custom board (ARM920T) and I have to do
> something about the UART (ns16550.c) driver to support (I know WD
> would disagree with this :p) XON/XOFF. I have to do this because my
There are certain situations where you actually may have to do
something like this, like when your serial connectionis over modem or
> board can support only < 19200 baudrates. At 19200 baudrate, I have a
This is NOT a valid reson. We use many boards at 9600 bps, without
any flow control. The baud rate has NOTHING to do with this.
> functional serial console but downloading binaries using loadb, kermit
> would always say that the remote host is not reponding (ERROR: Remote
> Kermit Not Responding). I debugged this on the getc level and
> verified that my board's U-Boot can accept the first few data from my
> PC's kermit and then the loadb function hangs, i.e. does not accept
> any data. I think this is because my UART's FIFO is not handled well,
> and probably needs software flow control.
You are wrong. This has NOTHING to do with flow control. Even slow
systems are fast enought to pick up characters loss-free at high baud
rates like 115200 bps - remember that we are single tasking, so the
CPU really has nothing more to do than wait for the characters. So a
_slow_ connection is only _easier_ to handle. If you have problems,
these have other reasons (like a misconfigured kermit ?).
> How do I register my interrupt routine that would send XOFF data to
First, you're wrong when you think that flow control would improve
Second, you are wrong when you think you need interrupts to implement
Don't waste your time, you're on a wrong track.
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
"Faith: not *wanting* to know what is true." - Friedrich Nietzsche
More information about the U-Boot