PXS20RM Datasheet, PDF (827/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

FlexRay Communication Controller
CFG
MSG
Message Buffer Header Field: Frame Header
Message Buffer Header Field: Data Field Offset
FR_MBIDXRn[MBIDX]
FR_MBCCSRn[CMT]
Message Buffer Data Field: DATA[0-N]
Message Buffer Header Field: Slot Status
FR_MBCCSRn[MBT/MTD]
FR_MBCCFRn[MTM/CHA/CHB/CCF*]
FR_MBFIDRn[FID]
NF
TX
CMT
SR
Figure 26-129. Single Transmit Message Buffer Access Regions
Table 26-105. Single Transmit Message Buffer Access Regions Description
Region
Access from
Application
Module
Region used for
CFG
MSG
NF
TX
CM
SR
read/write
read/write
—
—
—
—
—
—
read-only
read/write
read-only
read-only
Message Buffer Configuration
Message Data and Slot Status Access
Message Header Access for Null Frame Transmission
Message Transmission and Slot Status Update
Message Buffer Validation
Message Buffer Search
The trigger bits FR_MBCCSRn[EDT] and FR_MBCCSRn[LCKT], and the interrupt enable bit
FR_MBCCSRn[MBIE] are not under access control and can be accessed from the application at any time.
The status bits FR_MBCCSRn[EDS] and FR_MBCCSRn[LCKS] are not under access control and can be
accessed from the CC at any time.
The interrupt flag FR_MBCCSRn[MBIF] is not under access control and can be accessed from the
application and the CC at any time. CC clear access has higher priority.
The CC restricts its access to the regions depending on the current state of the message buffer. The
application must adhere to these restrictions in order to ensure data consistency. The transmit message
buffer states are given in Figure 26-130. A description of the states is given in Table 26-106, which also
provides the access scheme for the access regions.
The status bits FR_MBCCSRn[EDS] and FR_MBCCSRn[LCKS] provide the application with the
required message buffer status information. The internal status information is not visible to the application.
26.6.6.2.2 Message Buffer States
This section describes the transmit message buffer states and provides a state diagram.
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
26-115