[Tinyos-devel] lost packets from PC to the mote

[Vlado Handziski]

On Tmote Sky the Rosc increases the temperature stability of the DCO. Back
then I did not notice any changes in the message injection failure rate when
switching it on/off.

Vlado

On Mon, Apr 21, 2008 at 10:09 AM, Jan Hauer <jan.hauer at gmail.com> wrote:

> >  Some more details: I run the same test code on micaz (on which the
> >  baudrate is 57600) and no packets were lost. I also lowered the
> baudrate
> >  to 57600 for telosb and it also stop losing packets. I only tested with
> >  low (1 packet/s) data rates from PC to the mote.
>
> A possible explanation: on telosb UART1 clock source is SMCLK. The
> source of SMCLK is DCO/4. The DCO is highly temperature dependent but
> currently calibrated only once (when the node boots). When DCO
> frequency changes the UART baudrate will change also and this effect
> is more crucial at 115200 compared to 57600 baud (where a symbol is
> twice as long).
>
> Jan
>
> >
> >  Question for Ben: did you also notice this?
> >
> >
> >
> >  --
> >  Razvan ME
> >
> >  >> On Sat, Apr 19, 2008 at 3:47 AM, Razvan Musaloiu-E. <
> razvanm at cs.jhu.edu>
> >  >> wrote:
> >  >>
> >  >>> Hi!
> >  >>>
> >  >>> I just noticed that when a mote sends a lot of packets to a the PC,
> the
> >  >>> packets from the PC to the mote doesn't go reach the user
> application layer
> >  >>> some of the time. In the attached archive there is a test program
> that is
> >  >>> exposing this. The mote program is sending packets back-to-back
> while the PC
> >  >>> program (in Java) is receiving the packets and sends to the mote
> one packets
> >  >>> each second. I run the program on telosb in the following way:
> >  >>>
> >  >>> (console 1)$ ./sf 9001 /dev/ttyUSB0 115200
> >  >>> (console 2)$ java StressSerialTest -comm sf at localhost:9001
> >  >>>
> >  >>> The mote is toggling the blue led each time it receives a packet
> and it
> >  >>> should change state each time the RX led from the USB blinks. This
> doesn't
> >  >>> always happen: the RX led indicates a receive but the blue doesn't
> always
> >  >>> change its state. The (console 1) also shows lines like this:
> >  >>>        Note: write failed
> >  >>>        Note: write failed
> >  >>>        Note: write failed
> >  >>>        Note: write failed
> >  >>>
> >  >>> Did anyone else notice this behavior?
> >  >>>
> >  >>> --
> >  >>> Razvan ME
> >  >>>
> >  >>>
> >  >>
> >  >
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> >
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> >
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