[Tinyos-help] To send large payload in the TestSerial.

João Paulo Amaro da Costa Luz Carneiro jcarneiro at netcabo.pt
Tue Feb 3 07:09:19 PST 2009


I also made some tests a few months ago with an IRIS mote, stressing  
the packet size and periodicity of tranmission. The conclusion is  
quite obvious: larger packets = higher data loss (with the same  
transmission period).
I tested several combinations of packet sizes and time periods but  
sending 114Bytes:
- every 250ms between 2 motes installed with 4 meters of distance  
between them, I get 100% PRR (receive every packet sent) during a 15  
minutes period
- every 250ms between 3 motes installed with 4 meters of distance  
between them (forming a triangle), I get at least 20% of packet lost  
during a 60 minutes period

Anyway with a payload of 114 and sending every 250ms you would only  
get 456Bytes (assuming you could get 100% receive rate), which is far  
from your objective.



On 2009/02/03, at 13:52, Razvan Musaloiu-E. wrote:

> Hi!
> On Tue, 3 Feb 2009, kiseop Lee wrote:
>> Hello,
>> How does the TestSerial send large payload datas to host-PC by  
>> RS-232 ?
>> I have found that "TOSH_DATA_LENGTH 28" into CC2420.h file is used
>> in Packet.maxPayloadLength().
>> But I have modified it to 1300 and the test_serial_msg_t has a  
>> member array
>> which is composed
>> with 1200 bytes. Now, it does not operate.
>> I want to send 1200bytes per second to Host-PC by RS-232 and RF.
>> in this stage, I am testing only RS-232 and at next stage, I will  
>> send these
>> by RF.
>> Do you know this problem?
> Bad news: you cannot make the payload that big. All the send/receive
> interfaces the type uint8_t for the length. Moreover, for C2420 the
> maximum value for TOSH_DATA_LENGTH cannot exceed 114 (or 115) bytes
> because the internal buffer of chip is 128 bytes (including the  
> headers).
> All the best!
> Razvan ME
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