[Tinyos-help] ReceiveMsg and preemption on telos

Janos Sallai sallai at isis.vanderbilt.edu
Wed Sep 21 22:47:28 PDT 2005


You won't get the ReceiveMsg.receive event until your task is running.
TinyOS Tutorial Lesson 1 explains the preemption rules.

 

Try slicing up the CPU intensive computation into several tasks that run
to completion fast.

 

Janos

 

-----Original Message-----
From: tinyos-help-bounces at Millennium.Berkeley.EDU
[mailto:tinyos-help-bounces at Millennium.Berkeley.EDU] On Behalf Of Andrea
Pacini
Sent: Wednesday, September 21, 2005 7:19 PM
To: TinyOS HELP
Subject: [Tinyos-help] ReceiveMsg and preemption on telos

 

In what cases (not due to channel errors or mutliple transmission ) a
packet can be loss ?

In my case I have the same identical code that run on two tmote (telos)
which has the following simple structure :

 

// CPU intensive TASK

// SEND message 

 

(and a receivemsg event is present to handle packet arrives).

 

Running them it seems that if we start the two motes roughly at the same
time all works, but if we start with some seconds of difference the
first mote that runs SEND message sends a message but this message is
never received by the second mote (maybe because is doing a CPU
intensive task or because there is no preemption in some cases ?)

Is it possible that this lack of synchronization cause packet loss or
whatever the second mote is doing it always should receive the message ?
(I am sure that in my case the packet was lost)

 

Thanks 

Andrea





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