msCAN: receive-buffer | 68HC12 | EmbeddedRelated.com

I got a problem in understanding the system of buffers and filters in the msCAN-modul. First thing is, when sending a message from the tx-buffer to the canbus, the same message is written to the receivebuffer. Is the can- modul sensing the bus and therefore receive its own message? Secondly, why do I receive all the incoming messages from the canbus in my receivebuffer (in the debugger all messages appear at the address of the rx-foreground-buffer), even if I closed the filters. I thought there is a difference between fore- and backgroundbuffer. Shouldn't I see only the foregroundbuffer? Regards, Sebastian

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First: Yes, the modul recieves its own message, but doesn't set the recieve-Flag! Second: Is the recieve-bit set? "WARNING: To ensure data integrity, do not read the receive buffer registers while the RXF flag is cleared." (S.524 MC9S12DP256.pdf) Read the chapter "MSCAN" of the file "MC9S12DP256.pdf" for entire information. (You can get it from the Motorola-HP.) Regards, Christoph -----Urspr�ngliche Nachricht----- Von: Sebastian Schuster [mailto:] Gesendet: Donnerstag, 22. April 2004 08:51 An: Betreff: [68HC12] msCAN: receive-buffer I got a problem in understanding the system of buffers and filters in the msCAN-modul. First thing is, when sending a message from the tx-buffer to the canbus, the same message is written to the receivebuffer. Is the can- modul sensing the bus and therefore receive its own message? Secondly, why do I receive all the incoming messages from the canbus in my receivebuffer (in the debugger all messages appear at the address of the rx-foreground-buffer), even if I closed the filters. I thought there is a difference between fore- and backgroundbuffer. Shouldn't I see only the foregroundbuffer? Regards, Sebastian --------------------------------------------------------To learn more about Motorola Microcontrollers, please visit http://www.motorola.com/mcu o learn more about Motorola Microcontrollers, please visit http://www.motorola.com/mcu Yahoo! Groups Links

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Discussion Groups | 68HC12 | msCAN: receive-buffer

msCAN: receive-buffer - Sebastian Schuster - Apr 22 1:51:00 2004

AW: msCAN: receive-buffer - Christoph Br�gge - Apr 22 4:03:00 2004