Listen Only Mode of CAN Controller LPC1759

[gopaljatiya]

Hello,

I am trying to build a silent listener on the CAN Bus. I have configured the CANMOD to "Listen Only Mode".

I keep on getting the BUS Error. When i look at the details of it in CANICR, I can see that it is a "form Error".

Method of testing:

Using a PCAN I m sending a message on the CAN Bus. I have a CAN transeiver between the CAN lines and the LPC pins. I can see the the message is received in the buffer but the receive interrupt is never hit. I have enabled the receive interrupt and also enabled the CAN interrupt on the NVIC.

Can someone please let me know what am i doing wrong here, as i can see data in the buffer but receive interrupt is never getting hit. Is there something which I am missing. I can share more details if required to solve this issue.

[jeremyzhou]

Hi Gopal Jatiya，

To form CAN bus you need at least 2 active nodes. Message transmitted from one node must be ACKed by (at least one) another nodes. In listen only mode ACK's aren't send。

Have a great day,
TIC

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[gopaljatiya]

Thanks for the reply. I have a follow up question.

So, if there is another node that is active and will ACK the message, will listen mode only work if I just want to receive the message? The purpose of my device is to just listen on the CAN bus and never transmit anything.

So, should I operate in "Listen Only Mode" or "Normal" mode when there are other active nodes on the bus. In the mean while I am trying to make another node on this bus that shall be an active node to confirm the behaviour.

[jeremyzhou]

Hi Gopal Jatiya,

1) if there is another node that is active and will ACK the message, will listen mode only work if I just want to receive the message?

    Yes, I think so, please giving a shot.

Have a great day,
TIC

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