CAN using pic18f2580 and pca82c250

einton · Joined: 17 Nov 2009 Posts: 2

Hi guys I'm new to CAN. I'm trying to establish communication b/w two nodes using pic18f2580 and pca82c250 WITH MY OWN MADE BOARDS. But I'm unable to make nodes talking. The programs are indeed verified and I have also verified code in loopback mode. I'm applying 125 Kb/s.

(1) I'm connecting rs pin directly to ground, if I use resistor at here what should be the nominal value?
(2) I'm using 6-7 cm long TWISTED PAIR UTP cable.
(3) The data sheet uses 124 ohm termination resistor I'm using two 120 ohm (giving can bus resistance of 62 ohm) what difference it could.
(4) Can any one really post any working schematics.
(5) Any sort of test to check transceivers? I'm getting continuously 3.5v on canl and 2.5 on canl pins.
(6) I HAVE USED DIFFERENT BIT TIMING SETTINGS BUT NONE WORKS .
(7) The programs are verified and they are working on other systems.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Are you using the CCS compiler ? If so, then see the following post.
http://www.ccsinfo.com/forum/viewtopic.php?t=39792&start=7
It has instructions and a link to code which will test communication
between two CAN bus boards.

einton · Joined: 17 Nov 2009 Posts: 2

thanx dear I look over at the link, it is same as I'm working, but I have thoughts over gnd connection. I'm operating both nodes from same power supply so I think it got no issues. Tell me if any, but thanx for your reply. Please tell what are the usual problems when CAN bus is not working.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

I don't think you're using the CCS compiler so I can't help very much.
Just check your connections and find a web forum for your compiler.