FlexRay Communication Controller (FlexRay)MPC5644A Microcontroller Reference Manual, Rev. 6Freescale Semiconductor 1533Version 2.1 Rev A. A detailed description of the content and usage of the slot status is provided inSection 33.6.5.2.3, Slot status description”.33.6.2.2 Message buffer data fieldThe message buffer data field is a contiguous area of 2-byte entities. This field contains the frame payloaddata, or a part of it, of the frame to be transmitted to or received from the FlexRay bus. The minimumlength of this field depends on the specific message buffer configuration and is specified in the messagebuffer descriptions given in Section 33.6.3, Message buffer types”.33.6.3 Message buffer typesThe CC provides three different types of message buffers.• Individual Message Buffers• Receive Shadow Buffers• Receive FIFO BuffersFor each message buffer type the structure of the physical message buffer is identical. The message buffertypes differ only in the structure and content of message buffer control data, which control the relatedphysical message buffer. The message buffer control data are described in the following sections.33.6.3.1 Individual message buffersThe individual message buffers are used for all types of frame transmission and for dedicated framereception based on individual filter settings for each message buffer. The CC supports three types ofindividual message buffers, which are described in Section 33.6.6, Individual message buffer functionaldescription”.Each individual message buffer consists of two parts, the physical message buffer, which is located in theFlexRay memory area, and the message buffer control data, which are located in dedicated registers. Thestructure of an individual message buffer is given in Figure 33-114.Each individual message buffer has a message buffer number n assigned, which determines the set ofmessage buffer control registers associated to this individual message buffer. The individual messagebuffer with message buffer number n is controlled by the registers FR_MBCCSRn, FR_MBCCFRn,FR_MBFIDRn, and FR_MBIDXRn.The connection between the message buffer control registers and the physical message buffer isestablished by the message buffer index field MBIDX in the Message Buffer Index Registers(FR_MBIDXRn). The start address SADR_MBHF of the related message buffer header field in theFlexRay memory area is determined according to Equation 33-2.SADR_MBHF = (FR_MBIDXRn[MBIDX] * 10) + SMBA Eqn. 33-2
