
Chapter 13 FlexRay Communication Controller (FLEXRAY)
MC9S12XF - Family Reference Manual, Rev.1.19
Freescale Semiconductor
469
13.5.2.1
Register Reset
value on system reset. The registers mentioned above are located in physical memory blocks and, thus,
they are not affected by reset. For some register elds, additional reset conditions exist. These additional
reset conditions are mentioned in the detailed description of the register. The additional reset conditions
13.5.2.2
Register Write Access
This section describes the write access restriction terms that apply to all registers.
13.5.2.2.1
Register Write Access Restriction
For each register bit and register eld, the write access conditions are specied in the detailed register
description. A description of the write access conditions is given in
Table 13-6. If, for a specic register
bit or eld, none of the given write access conditions is fullled, any write attempt to this register bit or
eld is ignored without any notication. The values of the bits or elds are not changed. The condition
term [A or B] indicates that the register or eld can be written to if at least one of the conditions is fullled.
Reset Value
0
Resets to zero.
1
Resets to one.
–
Not dened after reset and not affected by reset.
Table 13-5. Additional Register Reset Conditions
Condition
Description
Protocol RUN Command
The register eld is reset when the application writes to RUN command “0101” to the
Message Buffer Disable
The register eld is reset when the application has disabled the message buffer.
This happens when the application writes 1 to the message buffer disable trigger bit
MBCCSRn.EDT while the message buffer is enabled (MBCCSn.EDS = 1) and the FlexRay
block grants the disable to the application by clearing the MBCCSRn.EDS bit.
Table 13-6. Register Write Access Restrictions
Condition
Indication
Description
Any Time
-
No write access restriction.
Disabled Mode
MCR.MEN = 0
Write access only when the FlexRay block is in Disabled Mode.
Normal Mode
MCR.MEN = 1
Write access only when the FlexRay block is in Normal Mode.
POC:cong
PSR0.PROTSTATE = POC:cong
Write access only when the Protocol is in the POC:cong state.
MB_DIS
MBCCSRn.EDS = 0
Write access only when the related Message Buffer is disabled.
Table 13-4. Register Access Conventions (continued)
Convention
Description