[Tinyos-devel] again about the baudrate issue for telos

Andreas Köpke koepke at tkn.tu-berlin.de
Mon Mar 2 23:11:33 PST 2009


Hi, this patch has one disadvantage: it makes the SF less suitable for devices 
like the NSLU2: writing/reading single bytes for 8 or more telosb leads to a 
high CPU load on an slug. 

Best, Andreas

On Dienstag 03 März 2009 00:06:37 Chieh-Jan (Mike) Liang wrote:
> Hi Eric,
>
> In my case, when the mote->pc packet rate is high, I get a a lot of
> "write fail" from the C serial forwarder, even at 57600. Here are my
> changes to the C serial forwarder:
>
> 1.) I have byte spacing to wait a little bit after sending each byte.
> Currently, this is 50 micro-sec, but I think it can be lower. Byte
> spacing was also recently added to the python T2 serial stack, tos.py.
> The hope is that the mote has some more time to handle the interrupt.
> 2.) Byte spacing helps a lot, but there were still some "write fail".
> So, I retry sending a packet if such case happens. I believe the Cpp
> serial forwarder already does this, but not the C version.
>
> I attached a patch. Please let me know if you see something weird.
>
> Thank you
>
> Mike




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