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ducharmemetal / ardupilot-mega

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Spurious zero bytes in STATUSTEXT messages #824

Open GoogleCodeExporter opened 9 years ago

GoogleCodeExporter commented 9 years ago 
I see between 5% and 10% of damaged packets on the USB link using (stock) 
firmware 2.50, 2.60 and 2.68.

After a detailed anaylsis, I have discovered the following reason:

Some of the STATUSTEXT messages do not have the payload length stated in the 
header. The difference between the length given in the header and the real 
length on wire seems to be one or more groups of zero bytes in between of two 
separate texts. 

> What steps will reproduce the problem?
1. record the serial stream, especially during boot phase with lots of text
2. analyse packet byte by byte

> What version of the product are you using? On what operating system?
2.50, 2.60, 2.68

Original issue reported on code.google.com by hsteinh...@gmx.de on 17 Dec 2012 at 3:20

GoogleCodeExporter commented 9 years ago 
Sorry - the destroyed message its not STATUSTEXT, but SYS_STATUS. An 
interesting fact is that a damaged SYS_STATUS generally seems to contain 
fragments of STATUSTEXTs - may be a dangling pointer somewhere?

Please see the follwing dump for details:
http://steinhaus-home.de/ardu/sys_status.png

Original comment by hsteinh...@gmx.de on 17 Dec 2012 at 8:44