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

[Razvan Musaloiu-E.]

Hi!

On Fri, 25 Apr 2008, Philip Levis wrote:

>
> On Apr 18, 2008, at 6:47 PM, Razvan Musaloiu-E. 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,
>
> When I run your test application on my machine, I do not see this behavior. I 
> was able to send 100 packets (the program ran for 100 seconds) with no write 
> fails. What write fail rate do you observe?

Here are the loss rates I got so far:

Python in Linux:
 	      115200        57600
 	      PC   Laptop   PC Laptop
 	MoteA 20%   18%     0%  0%
 	MoteB 33%   20%     0%  0%
 	MoteC 34%   17%     0%  0%

Native Python in Windows:
 	      115200  57600
 	MoteD 68%     88%

Java application using C sf in Linux:
               115200  57600
               PC      PC
         MoteC 18%     0%

I all the test I send between 100-120 packets.

I haven't check the serial hardware overflow indicator yet but that's what 
I'm going to do next.

--
Razvan ME

> I ran your Java application connected to a C serial forwarder.
>
> Phil