mfr4200 Freescale Semiconductor, Inc, mfr4200 Datasheet - Page 181

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

3.5.6.2.2
The host can configure some message buffers of the CC as double transmit message buffers. If there is at
least one double transmit message buffer configured, then the CC can actively transmit frames out of the
connected FlexRay network.
To configure a double transmit message buffer
The
driven transmit operation in normal operation.
The
driven transmit operation.
Host Operations with a Double Transmit Message Buffer during Transmission
The host can perform the following operations on a double transmit message buffer.
Main principles of the host operations with double transmit message buffers:
Freescale Semiconductor
1. Configure the even number message buffer as a transmit message buffer, in accordance with the
2. Set the message buffer type bit BT (see
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Figure 3-140
Figure 3-139
configuration procedure and principles.
and Status
copied to the CC part buffers automatically).
Lock buffer for reading and/or modifying.
Read message buffer slot status vector, data and configuration.
Write data.
Commit and unlock for transmission.
The host always operates with host part buffers.
The host can perform operations with host part buffers independent of CC transmit operations from
the CC 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 field not equal to ‘0’.
The addresses of the host part buffers do not change during normal operation.
The host has read-only access to the CC part buffer BUFCSnR registers.
number
(even)
Buffer
Doubled Buffer Data collection during Transmit Operation
When the CC transmits a null frame, it does not change the BUFCSnR
registers of the buffers.
shows an example of a doubled transmit message buffer data collection during the event
shows an example of a double transmit message buffer data collection during the state
Register”) to 1 — host part buffer of double transmit message buffers (configuration is
Figure 3-138. Double Transmit Message Buffer Structure
Host Part Buffer n
BUFCS(n)
MFR4200 Data Sheet, Rev. 0
(Figure
Section 3.4.1, “Message Buffer Control, Configuration
NOTE
Number+1
3-138), the follow steps must be performed.
Buffer
(odd)
Message Buffer Handling and Operations
CC part Buffer n+1
BUFCS(n+1)
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