SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
Table 24-742 shows how a receive object for data frames can be initialized.
MsgVal | Arb | Data | Mask | EoB | Dir | NewDat | MsgLst | RxIE | TxIE | IntPnd | RmtEn | TxRqst |
---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | appl. | appl. | appl. | 1 | 0 | 0 | 0 | appl. | 0 | 0 | 0 | 0 |
The arbitration bits (ID[28:0] and Xtd bit) are given by the application. They define the identifier and type of accepted received messages. 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 data frame with an 11-bit Identifier is received, ID[17:0] is set to ‘0’.
The data length code (DLC[3:0]) is given by the application. When the message handler stores a data frame in the message object, it will store the received data length code and eight data bytes. If the data length code is less than 8, the remaining bytes of the message object may be overwritten by non specified values.
The mask bits (Msk[28:0], UMask, MXtd, and MDir bits) may be used (UMask = ’1’) to allow groups of data frames with similar identifiers to be accepted. The Dir bit should not be masked in typical applications. If some bits of the mask bits are set to “don’t care,” the corresponding bits of the arbitration register (DCAN_IF1ARB, DCAN_IF2ARB, DCAN_IF3ARB) will be overwritten by the bits of the stored data frame.
If the RxIE bit is set, the IntPnd bit will be set when a received data frame is accepted and stored in the message object.
If the TxRqst bit is set, the transmission of a remote frame with the same identifier as actually stored in the arbitration bits will be triggered. The content of the arbitration bits may change if the mask bits are used (UMask = ’1’) for acceptance filtering.