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TM4C123AE6PM: TM4C123AE6PM

Ajith V
Prodigy 10 points
Part Number: TM4C123AE6PM

Tool/software:

How Many CAN hardware filters we can set for CAN0 BASE and CAN1 BASE?

Using void CANMessageSet(uint32_t ui32Base, uint32_t ui32ObjID, tCANMsgObject *psMsgObject, tMsgObjType eMsgType)

As referred from the manual the parameter says

 ui32Base is the base address of the CAN controller.

ui32ObjID is the object number to configure (1-32).

psMsgObject is a pointer to a structure containing message object settings.

eMsgType indicates the type of message for this object

So In total 32 Hardware filters can be set for receiving.

Questions:

1) CAN I use this Api with CAN0BASE only to set all the 32 filters? 

 CANMessageSet(CAN0_BASE, (uint32_t)Can_obj_id, &CAN_Raw_Recieve, MSG_OBJ_TYPE_RX);
 
2) Is it that we have to use 16 - 16 filters for each base? 16 for CAN0_BASE and 16 for CAN1_BASE.
  • 0
    TI__Guru**** 183536 points
    Ajith V said:
    So In total 32 Hardware filters can be set for receiving.

    Hi,

      I think you may have a misunderstanding on the definition of a message object vs acceptance filters. Each can module has up to 32 message objects. We don't call the filters. As for receiving, you can configure each message object using acceptance masks to receive up to the length of message ID. For example, you can configure message object 1 to receive any message IDs by configuring the acceptable filter to 0. As another example, you can configure message object 1 only receive message ID that is equal to 0x12 and message object 2 to only receive ID equal to 0x34 and message object 3 to receive ID equal to 0x56. 

    17.3.6 Accepting Received Message Objects
    When the arbitration and control field (the ID and XTD bits in the CANIFnARB2 and the RMTEN and
    DLC[3:0] bits of the CANIFnMCTL register) of an incoming message is completely shifted into
    the CAN controller, the message handling capability of the controller starts scanning the message
    RAM for a matching valid message object. To scan the message RAM for a matching message
    object, the controller uses the acceptance filtering programmed through the mask bits in the
    CANIFnMSKn register and enabled using the UMASK bit in the CANIFnMCTL register. Each valid

    message object, starting with object 1, is compared with the incoming message to locate a matching
    message object in the message RAM. If a match occurs, the scanning is stopped and the message
    handler proceeds depending on whether it is a data frame or remote frame that was received.

  • 0 in reply to Charles Tsai
    Prodigy 10 points

    Hello Charles Thanks for the reply,

    By hardware filter I meant the same as you stated

    configuring message object 1 only receive message ID that is equal to 0x12 and message object 2 to only receive ID equal to 0x34 and message object 3 to receive ID equal to 0x56.  and so on till 32.

    So, in this way we can configure max up to 32 objects.

    My question was in SDK level, since we have Two CAN Interface CAN0 Base and CAN1 Base

    Here I wanted to know is there splitting of 16-16 message object associated with each interface?

    and I was basically trying to configure 20 message objects with CAN0 Base where only 16 were working (CAN0 ISR reception were there).

    So, to configure the other 4 objects do I need to use CAN1 Base?

    and also as you stated

    To scan the message RAM for a matching message
    object, the controller uses the acceptance filtering programmed through the mask bits in the
    CANIFnMSKn register and enabled using the UMASK bit in the CANIFnMCTL register. 

    we have CANIFnMSKn register and CANIFnMCTL register separately for each Interface.

     

  • +1 in reply to Ajith V
    TI__Guru**** 183536 points
    Ajith V said:
    Here I wanted to know is there splitting of 16-16 message object associated with each interface?

    What do you mean by splitting? There are 32 message objects for each CAN module.

    Ajith V said:

    and I was basically trying to configure 20 message objects with CAN0 Base where only 16 were working (CAN0 ISR reception were there).

    So, to configure the other 4 objects do I need to use CAN1 Base?

    You should be able to use all 32 message objects in CAN0. 

  • 0 in reply to Charles Tsai
    Prodigy 10 points

    Thanks Charles I just had confusions with my object ids.

    Sorted now thanks for your help