PXR40RM Datasheet, PDF (693/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

FlexRay Communication Controller (FLEXRAY)
same time as the application locks the message buffer by the HL transition, the intermediate state is CCRx
and the resulting state is locked buffer subscribed state HLckCCRx.
Table 22-104. Receive Message Buffer Transition Priorities
State
Idle
HLck
CCRx
Priorities
BS > HD
BS > HD
SSS > HL
Description
module vs. application
Buffer Subscribed > Message Buffer Disable
Buffer Subscribed > Message Buffer Disable
Slot or Segment Start > Message Buffer Lock
22.6.6.3.2 Message Reception
As a result of the message buffer search, the controller changes the state of up to two enabled receive
message buffers from either idle state Idle or locked state HLck to the either subscribed state CCBs or
locked buffer subscribed state HLckCCBs by triggering the buffer subscribed transition BS.
If the receive message buffers for the next slot are assigned to both channels, then at most one receive
message buffer is changed to a buffer subscribed state.
If more than one matching message buffers assigned to a certain channel, then only the message buffer
with the lowest message buffer number is in one of the states mentioned above.
With the start of the next static or dynamic slot the module trigger the slot start transition SLS. This
changes the state of the subscribed receive message buffers from either CCBs to CCRx or from
HLckCCBs to HLckCCRx, respectively.
During the reception slot, the received frame data are written into the shadow buffers. For details on
receive shadow buffers, see Section 22.6.6.3.5, Receive Shadow Buffers Concept. The data and status of
the receive message buffers that are the CCRx or HLckCCRx are not modified in the reception slot.
22.6.6.3.3 Message Buffer Update
With the start of the next static or dynamic slot or with the start of the symbol window or NIT, the module
triggers the slot or segment start transition SSS. This transition changes the state of the receiving receive
message buffers from either CCRx to CCSu or from HLckCCRx to HLck, respectively.
If a message buffer was in the locked state HLckCCRx, no update will be performed. The received data
are lost. This is indicated by setting the Frame Lost Channel A/B Error Flag FRLA_EF/FRLB_EF in the
CHI Error Flag Register (CHIERFR).
If a message buffer was in the CCRx state it is now in the CCSu state. After the evaluation of the slot status
provided by the PE the message buffer is updated. The message buffer update depends on the slot status
bits and the segment the message buffer is assigned to. This is described in Table 22-105.
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
22-109