I want to send a message using Can Controller T89C51CC01 right now, I am not sure when the message is sent. Right after CANCONCH is set? Using the debug program in Keil, I could clearly see the message is on the can channel I assigned to. But the value of pin P4.0 and P4.1 don't change at all. If the can controller is sending messages, P4.0(Tx) P4.1(Rx0) should change from time to time right? How could I send messages to the can bus? Everybody, please help me.
Vincent, Your RX pin should see what is on the CAN bus if it's working correctly. Maybe you can set up this can controller to accept it's own messages for purposes of testing. That will not tell you if your BAUD rate is set correctly. Only way to tell that, other that being 100% sure of your settings, is to have independent means of testing. Try a google search on PCANview. I forget the name of the company, but they make a cheap USB to CAN converter that can listen for ALL can messaged at specific settings. You may want to take a look at B & B lectronics. They make a lot of neat converters as well. They can supposebly send CAN messages, but when I was working with this stuff, I was never able to pick them up on my controllers. For your application, are you planning on making more than one controller? Andy
BTW, is your CAN bus (output of tranciever)connected to anything? I'm thinking that if it is not, you wont't see anything on your RX pin (nothing to see). I've been unemployed for the past 13 weeks (though I think thats about to change) and have been allowing cobwebs to form on my brain I'm afraid. I'm in the process of reviewing my CAN stuff as my possible new job will be dealing with it extensively. Can you give a descition of your physical layer? Andy
Dear Andy Thank you for your advice. I'll give it a shot. You saved me a lot of time. As you mentioned, I am not only working with CAN controller, but also with a chip called "FPGA". well, I am just doing a small part of a huge project related to car. What I need to do is to read the command from the pc user, then analyse the request sent with usb stored in "FPGA"'s register with considering the current situation and behave in the right way. Vince
Andy Actually, for the Can Controller, we have two of them, both of which are connected to the CAN bus. We also have a "FPGA" as a router and a usb as a connecter with the pc. we can discuss it in detail via Email. My life in the lab is so tough. have a nice day. Vince