AN2283 Freescale Semiconductor / Motorola, AN2283 Datasheet - Page 15

• Manufacturer Part Number: AN2283
• Description: Scalable Controller Area Network (MSCAN)
• Manufacturer: Freescale Semiconductor / Motorola

Abort Request
MOTOROLA
Motorola Scalable Controller Area Network (MSCAN) Interrupts
An abort request of a message scheduled for transmission may be necessary:
Figure 11
is requested (ABTRQx = 1)
1. When a message in a buffer is taking too long to transmit it eventually
2. When a state change occurs in a module that requires an abort of a
3. When all three message buffers are filled with messages to be
Freescale Semiconductor, Inc.
ACKNOWLEDGED
For More Information On This Product,
MESSAGE PENDING
TRANSMISSION
ABTAKx = 1
times out (from the user’s application). This is because either it has a
lower priority relative to the other messages in the other two message
buffers or message traffic has higher priority resulting in loss of
arbitration with the bus. The user’s application code may elect to monitor
the time a message is queued in a transmit buffer and remove the
message if the data is determined to be stale.
pending message, with an updated message to be sent in its place.
scheduled for transmission and a higher priority message (relative to the
other messages) needs to be transmitted.
ABORT
shows the steps taken by the MSCAN when an abort of a message
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Figure 11. Abort Message Request Flowchart
TRANSMISSION ENDS WITH ERRORS
LOSS OF ARBITRATION
ABTRQx = 1
REQUEST
ABORT
THE MESSAGE IN BUFFER
IS IN TRANSMISSION
TRANSMISSION
ENDS
TRASMISSION COMPLETE
WITH NO ERRORS
Abort Process Overview
BUFFER EMPTY
NOTHING TO
ABORT
AN2283/D
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