PXR40RM Datasheet, PDF (706/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

FlexRay Communication Controller (FLEXRAY)
The cycle counter filter of a message buffer matches the communication cycle with the number CYCCNT
if at least one of the following conditions evaluates to true:
MBCCFRnCCFE = 0
Eqn. 22-12
CYCCNT & MBCCFRnCCFMSK = MBCCFRnCCFVAL & MBCCFRnCCFMSK
Eqn. 22-13
22.6.7.2 Message Buffer Channel Assignment Consistency
The message buffer channel assignment given by the CHA and CHB bits in the Message Buffer Cycle
Counter Filter Registers (MBCCFRn) defines the channels on which the message buffer will receive or
transmit. The message buffer with number n transmits or receives on channel A if MBCCFRn[CHA] = 1
and transmits or receives on channel B if MBCCFRn[CHB] = 1.
To ensure correct message buffer operation, all message buffers assigned to the same slot and with the
same priority must have a consistent channel assignment. That means they must be either assigned to one
channel only, or must be assigned to both channels. The behavior of the message buffer search is not
defined, if both types of channel assignments occur for one slot and priority. An inconsistent channel
assignment for message buffer 0 and message buffer 1 is depicted in Figure 22-136.
MB0
MB1
MBFIDR0[FID] = 10 MBCCFR0[CHA] = 1, MBCCFR0[CHB] = 0
single channel assignment
MBFIDR1[FID] = 10 MBCCFR1[CHA] = 1, MBCCFR1[CHB] = 1
dual channel assignment
Figure 22-136. Inconsistent Channel Assignment
22.6.7.3 Node Related Slot Multiplexing
The term Node Related Slot Multiplexing applies to the dynamic segment only and refers to the
functionality if there are transmit as well as receive message buffers are configured for the same slot.
According to Table 22-113 the transmit buffer is only found if the cycle counter filter matches, and the
buffer is not locked and committed. In all other cases, the receive buffer will be found. Thus, if the block
has no data to transmit in a dynamic slot, it is able to receive frames on that slot.
22.6.7.4 Message Buffer Search Error
If the message buffer search is running while the next message buffer search start event appears, the
message buffer search is stopped and the Message Buffer Search Error Flag MSB_EF is set in the CHI
Error Flag Register (CHIERFR). This appears only if the CHI frequency is too low to search through all
message buffers within the NIT or a minislot. The message buffer result is not defined in this case. For
more details see Section 22.7.3, Number of Usable Message Buffers.
22.6.8 Individual Message Buffer Reconfiguration
The initial configuration of each individual message buffer can be changed even when the protocol is not
in the POC:config state. This is referred to as individual message buffer reconfiguration. The
configuration bits and fields that can be changed are given in the section on Specific Configuration Data.
22-122
PXR40 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor