39.9.1 Message RAM Configuration

The Message RAM has a width of 32 bits. In case parity checking or ECC is used a respective number of bits has to be added to each word. The CAN module can be configured to allocate up to 4352 words in the Message RAM. It is not necessary to configure each of the sections listed in the figure below, nor is there any restriction with respect to the sequence of the sections.

When operated in CAN FD mode the required Message RAM size strongly depends on the element size configured for Rx FIFO 0, Rx FIFO 1, Rx Buffers, and Tx Buffers via RXESC.F0DS, RXESC.F1DS, RXESC.RBDS, and TXESC.TBDS.

Figure 39-12. Message RAM Configuration

When the CAN addresses the Message RAM it addresses 32-bit words, not single bytes. The configurable start addresses are 32-bit word addresses (i.e., only bits 15 to 2 are evaluated and the two LSBs are ignored).

Note: Message RAM can only be located in the first 64 KB area of the system RAM.
Warning: The CAN does not check for erroneous configuration of the Message RAM. Especially the configuration of the start addresses of the different sections and the number of elements of each section has to be done carefully to avoid falsification or loss of data.