
Chapter 13 FlexRay Communication Controller (FLEXRAY)
MC9S12XF - Family Reference Manual, Rev.1.19
Freescale Semiconductor
585
13.6.8
Individual Message Buffer Reconguration
The initial conguration of each individual message buffer can be changed even when the protocol is not
in the POC:cong state. This is referred to as individual message buffer reconguration. The conguration
protocol is out of the POC:cong state.
13.6.8.1
Reconguration Schemes
Depending on the target and destination basic state of the message buffer that is to be recongured, there
are three reconguration schemes.
13.6.8.1.1
Basic Type Not Changed (RC1)
A reconguration will not change the basic type of the individual message buffer, if both the message
buffer transfer direction bit MBCCSn.MTD and the message buffer type bit MBCCSn.MBT are not
changed. This type of reconguration is denoted by RC1 in
Figure 13-131. Single transmit and receive
message buffers can be RC1-recongured when in the HDis or HDisLck state. Double transmit message
buffers can be RC1-recongured if both the transmit side and the commit side are in the HDis state.
13.6.8.1.2
Buffer Type Not Changed (RC2)
A reconguration 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 reconguration is denoted by RC2 in
Figure 13-131. It applies only to single transmit and receive message buffers. Single transmit and receive
message buffers can be RC2-recongured when in the HDis or HDisLck state.
13.6.8.1.3
Buffer Type Changed (RC3)
A reconguration will change the buffer type of the individual message buffer if the message buffer type
bit MBCCSRn.MBT is changed. This type of reconguration is denoted by RC3 in
Figure 13-131. The
RC3 reconguration 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 recongured if they are in the
HDis state.
Figure 13-131. Message Buffer Reconguration Scheme
single RX
single TX
double TX (commit side)
double TX (transmit side)
RC1
RC2
RC3