On 09/23/11 15:27, Damien R. wrote: > On 23/09/11 11:11, Damien R. wrote: >> Hi, >> >> I'm using socket can with the raw socket protocol and I receive messages >> with a 11bits identifier (eg: 0x1C) but the can_id in the raw frame has >> a size of 32bits. So, I have the following questions: >> - How can I retrieve the 11bits identifier in the can_id ? >> - Can you explain the meaning of each bit in the cand_id ? >> - j1939 use a 29bits identifier, how can I retrieve the 29bits >> identifier in the can_id ? > > Sorry, I did not see the following part of the linux/can.h > > /* > * Controller Area Network Identifier structure > * > * bit 0-28 : CAN identifier (11/29 bit) > * bit 29 : error frame flag (0 = data frame, 1 = error frame) > * bit 30 : remote transmission request flag (1 = rtr frame) > * bit 31 : frame format flag (0 = standard 11 bit, 1 = extended 29 bit) > */ > typedef __u32 canid_t; > > So can someone explain how bits are arranged with a 11 bits identifier? Is it > this 0...0 identifier or identifier 0...0 or something else?
Hello Damien, you may look into http://lxr.linux.no/#linux+v3.0.4/Documentation/networking/can.txt as well as into some sample programs you can find in the trunk/test directory of the SocketCAN SVN on BerliOS: http://developer.berlios.de/svn/?group_id=6475 The identifier is always a 32 bit value you can access as shown in the examples. No need to think about the endianess of this operations on application level. Regards, Oliver _______________________________________________ Socketcan-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/socketcan-users
