[Tinyos-devel] CRC bug

[Roman Lim]

A also get corrupt information, when i extract packet information 
without using the serial stack. Until now, I did not spend a lot of time 
finding the source of these errors.
In my application, I only notice bad packets, when they contain 
obviously wrong routing information.

Roman

Omprakash Gnawali wrote:
> I have also seen a "few" bad node id's with CTP and default cc2420
> stack in the past but no such incident in the recent experiments.
> Sometimes, I also see corrupt packets (for example, pkts larger than
> they should be). Are you sure what you are seeing is due to the radio
> stack and not the serial stack? And not CTP or other pieces of
> software that might be stomping on the pkt?
> 
> - om_p
> 
> On Jan 8, 2008 9:06 AM, Roman Lim <rlim at ee.ethz.ch> wrote:
>> I did also observe wrong packets in a testbed with tmote sky nodes. the
>> attached picture shows the network status after a 2.5 week testrun (ctp
>> with low power mac). The red nodes at the bottom do not exist in the
>> real network, but somehow their ids reached the visualization app.
>> I am actually using a modified version of the current cc2420 stack, but
>> I did not touch the crc check part in the CC2420ReceiveP.
>>
>> Roman
>>
>> David Moss wrote:
>>> The continueRead() when the length shows a bad packet is supposed to read
>>> out the RX FIFO as if it were a good packet, but the CRC should fail (65534
>>> out of 65535 times) when complete.
>>>
>>> The S_RX_PAYLOAD is simply there to skip any kind of acknowledgement
>>> checking.
>>>
>>> How many bad packets are you seeing, exactly?  And I wonder if anyone else
>>> is having the same problem?  When I don't have CRC's enabled, I can really
>>> tell a difference in the amount and types of packets received, especially
>>> when my nodes are on the edge of communication.
>>>
>>> -David
>>>
>>>
>>>