[Tinyos-devel] TelosB as base station?

[Steve McKown]

Hi Matt,

I've seen this problem too (C SDK, Linux host).  Here's the text of a message 
I posted last week.  Perhaps this is what is happening in your case as well?

---- Forwarded message ----
Hi,

serialsource.c does not have a maintainer attribution, so I'm posting this 
here.

In TinyOS 2.0.x, the C SDK's serialsource.c contains a logic error in 
write_serial_packet() that can cause a deadlock.  This situation occurs when 
write_serial_packet() is called by the host and the attached mote fails to 
see the ending SYNC delimiter sent (due to a communication error).  The host 
waits in read_and_process() for an ack from the mote, and the mote waits in 
RXSTATE_INFO for more data from the host.  The deadlock is broken if the mote 
forwards a radio packet to the host.

The patch below may be a suitable resolution.

Cheers,
Steve

Index: serialsource.c
===================================================================
--- serialsource.c      (revision 1024)
+++ serialsource.c      (working copy)
@@ -768,6 +768,9 @@
     {
       struct packet_list *entry;
       
+      if (source_wait(src, &deadline) < 0)
+       return 1;
+
       read_and_process(src);
       entry = pop_protocol_packet(src, P_ACK);
       if (entry)
@@ -779,8 +782,6 @@
          if (acked == src->send.seqno)
            return 0;
        }
-      else if (source_wait(src, &deadline) < 0)
-       return 1;
     }
 }
 
---- End of forwarded message ----



On Thursday 05 July 2007 06:58:04 am Matt Welsh wrote:
> Hi folks,
>
> We have been having continued problems with using a TelosB mote as a
> base station and I'm wondering if there's something we're doing wrong.
> Basically, using BaseStationCC2420 on a TelosB along with the C-based
> serialforwarder is just incredibly unstable. It seems to hang after
> bursts of packets and we usually have to restart the base station mote.
> (The code in support/sdk/c/serialsource.c also prints the quite useful
> error message 'foo' - apparently when no data is available on the serial
> port - we commented that out long ago.)
>
> Not sure if this is a problem with the TelosB, the sf, or both. I
> remember having similar problems with TinyOS 1.x and am somewhat
> surprised this hasn't been resolved in 2.x - or maybe it has and we
> don't know the fix?
>
> We do find that MicaZ motes are very stable as base stations (running
> for weeks at a time without any hang).
>
> Thanks -
> Matt
>
>
>
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