PXN20RM Datasheet, PDF (739/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

FlexRay Communication Controller (FlexRAY)
26.6.7.4 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 26.7.3, Number of Usable Message Buffers.
26.6.8 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.
The common configuration data given in the section on Specific Configuration Data cannot be
reconfigured when the protocol is out of the POC:config state.
26.6.8.1 Reconfiguration Schemes
Depending on the target and destination basic state of the message buffer that is to be reconfigured, there
are three reconfiguration schemes.
26.6.8.1.1 Basic Type Not Changed (RC1)
A reconfiguration will not change the basic type of the individual message buffer, if both the message
buffer transfer direction bit MBCCSRn[MTD] and the message buffer type bit MBCCSRn[MBT] are not
changed. This type of reconfiguration is denoted by RC1 in Figure 26-137. Single transmit and receive
message buffers can be RC1-reconfigured when in the HDis or HDisLck state. Double transmit message
buffers can be RC1-reconfigured if both the transmit side and the commit side are in the HDis state.
26.6.8.1.2 Buffer Type Not Changed (RC2)
A reconfiguration will not change the buffer type of the individual message buffer if the message buffer
buffer type bit MBCCSRn[MBT] is not changed. This type of reconfiguration is denoted by RC2 in
Figure 26-137. It applies only to single transmit and receive message buffers. Single transmit and receive
message buffers can be RC2-reconfigured when in the HDis or HDisLck state.
26.6.8.1.3 Buffer Type Changed (RC3)
A reconfiguration will change the buffer type of the individual message buffer if the message buffer type
bit MBCCSRn[MBT] is changed. This type of reconfiguration is denoted by RC3 in Figure 26-137. The
RC3 reconfiguration splits one double buffer into two single buffers or combines two single buffer into
one double buffer. In the later case, the two single message buffers must have consecutive message buffer
numbers and the smaller one must be even. Message Buffers can be RC3 reconfigured if they are in the
HDis state.
Freescale Semiconductor
PXN20 Microcontroller Reference Manual, Rev. 1
26-125