Question regarding usrp2_basic.cc

GNU Radio
1

Hi,

I have been browsing the sources for the usrp2, so that I’m familiar
enough with the code when the new usrp2 comes. I have a million
questions regarding it, but there is one simple one for starters. At
line 70 in my usrp_basic.cc (svn-rev 8510), i have the following line of
code:

#define MAX_PKTLEN 1512 //biggest thing USRP2 can swallow
// (14-byte ethernet hdr

  • 1500 byte payload)

My question is; Is there something I have missed regarding the packets
and their format, is this a typo, is it something that everybody else
knows (for instance -“you always have to pad the packets with one byte”
or similar), or something completely different than the above
suggestions?

Cheers
//Mattias K.

2

On Thu, Jul 03, 2008 at 08:23:16PM +0200, Mattias K. wrote:

My question is; Is there something I have missed regarding the packets and
their format, is this a typo, is it something that everybody else knows
(for instance -“you always have to pad the packets with one byte” or
similar), or something completely different than the above suggestions?

Cheers
//Mattias K.

Oh, you want to know about the missing 2 bytes :wink:

The reason it’s 1512 and not 1514 is that the USRP2 always writes
32-bit words to the ethernet.

Eric