mfr4200 Freescale Semiconductor, Inc, mfr4200 Datasheet - Page 182

• Manufacturer Part Number: mfr4200
• Description: Flexray Communication Controllers
• Manufacturer: Freescale Semiconductor, Inc

MFR4200 FlexRay Communication Controller
CC Operations with a Double Transmit Message Buffer During Transmission
The CC performs the following operations on a double transmit message buffer.
Main principles of CC operations with double transmit buffers:
As it is presented in
transmit message buffer are the same as they are on a single transmit message buffer. However, CC
operations with host part and CC part buffers are different.
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1. Lock buffer for transmission.
2. Update the message buffer slot status vector of the host and the CC part buffers.
3. Swap host and CC part buffers after commitment for transmission.
4. Copy the CC part buffer to the host part buffer during commitment for transmission. The CC
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The host operates with a double transmit message buffer in the same way as it does with a single
transmit message buffer.
The host can receive an IFLG interrupt after transmission of a committed CC part buffer.
The host cannot lock a host part buffer (read value of the LOCK= 0) during swap and copy
procedures.
The host part buffer of a double transmit message buffer cannot be locked (read back value of the
LOCK= 0), if the host has committed the host part buffer for transmission but the BUFCMT bit of
the CC part buffer is still ‘1’ (a frame has not yet been transmitted).
if the host has committed a host part buffer of a double message buffer for transmission, the CC
performs an atomic swap of the host part and CC part buffers including the BUFCSnR registers of
the host and the CC part buffers, and starts a copy process.
copies the following fields from a CC part buffer of a double transmit buffer to a host part buffer
(see
— R*
— PP
— Frame ID
— Payload length
— Header CRC
— Data[0:31]
— Message buffer slot status vector
The CC may perform transmit operations from the CC part buffers while the host updates the host
part buffers.
Data exchange is based on access requests and acknowledge flags.
The host and the CC operate only with configured buffers that have frame ID fields not equal to ‘0’.
The numbers of the CC part buffers do not change during normal operation.
Section 3.5, “Message Buffer Handling and
Section 3.5.6, “Message Buffer
MFR4200 Data Sheet, Rev. 0
Operations”, host operations on a host part of a double
Operations”):
Freescale Semiconductor