SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The IF3 register set can automatically be updated with received message objects without the need to initiate the transfer from message RAM by software. The intention of this feature of IF3 is to provide an interface for the DMA to read packets efficiently. The automatic update functionality can be programmed for each message object (DCAN_IF3UPD12 to DCAN_IF3UPD78).
All valid message objects in message RAM which are configured for automatic update, will be checked for active NewDat flags. If such a message object is found, it will be transferred to the IF3 register (if no previous DMA transfers are ongoing), controlled by IF3 Observation register (DCAN_IF3OBS). If more than one NewDat flag is active, the message object with the lowest number has the highest priority for automatic IF3 update.
The NewDat bit in the message object will be reset by a transfer to IF3.
If DCAN internal IF3 update is complete, a DMA request is generated. The DMA request stays active until first read access to one of the IF3 registers. The DMA functionality has to be enabled by setting bit DCAN_CTL[20] DE3 = 1.
The IF3 register set cannot be used for transferring data into message objects.