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Functional Description
23.3.14.4 Configuration of a Single Receive Object for Remote Frames
Table 23-6 shows how a receive object for remote frames can be initialized.
Table 23-6. Initialization of a Single Receive Object for Remote Frames
MsgVal Arb Data Mask EoB Dir NewDat MsgLst RxIE TxIE IntPnd RmtEn TxRqst
1 appl. appl. appl. 1 1 0 0 appl. 0 0 0 0
A receive object for remote frames may be used to monitor remote frames on the CAN bus. The remote
frame stored in the receive object will not trigger the transmission of a data frame. Receive objects for
remote frames may be expanded to a FIFO buffer (see Section 23.3.14.5).
UMask must be set to ‘1.’ The mask bits (Msk[28:0], UMask, MXtd, and MDir bits) may be set to “must-
match” or to “don’t care,” to allow groups of remote frames with similar identifiers to be accepted. The Dir
bit should not be masked in typical applications. For details, see Section 23.3.15.8.
The arbitration bits (ID[28:0] and Xtd bit) may be given by the application. They define the identifier and
type of accepted received remote frames. If some bits of the mask bits are set to “don’t care,” the
corresponding bits of the arbitration bits will be overwritten by the bits of the stored remote frame. If an 11-
bit Identifier (standard frame) is used (Xtd = ‘0’), it is programmed to ID[28:18]. In this case, ID[17:0] can
be ignored. When a remote frame with an 11-bit Identifier is received, ID[17:0] will be set to ‘0.’
The data length code (DLC[3:0]) may be given by the application. When the message handler stores a
remote frame in the message object, it will store the received data length code. The data bytes of the
message object will remain unchanged.
If the RxIE bit is set, the IntPnd bit will be set when a received remote frame is accepted and stored in the
message object.
23.3.14.5 Configuration of a FIFO Buffer
With the exception of the EoB bit, the configuration of receive objects belonging to a FIFO buffer is the
same as the configuration of a single receive object.
To concatenate multiple message objects to a FIFO buffer, the identifiers and masks (if used) of these
message objects have to be programmed to matching values. Due to the implicit priority of the message
objects, the message object with the lowest number will be the first message object of the FIFO buffer.
The EoB bit of all message objects of a FIFO buffer except the last one have to be programmed to zero.
The EoB bits of the last message object of a FIFO Buffer is set to one, configuring it as the end of the
block.
3901
SPRUH73H–October 2011–Revised April 2013 Controller Area Network (CAN)
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