Freescale Semiconductor, Inc.
MSCAN Controller
sent successfully. The flag is also set by the msCAN12 when the
transmission request was successfully aborted due to a pending abort
request (msCAN12 Transmitter Control Register (CTCR)). If not masked,
a transmit interrupt is pending while this flag is set.
Clearing a TXEx flag also clears the corresponding ABTAKx flag (see
above). When a TXEx flag is set, the corresponding ABTRQx bit is
cleared (see msCAN12 Transmitter Control Register (CTCR)).
0 = The associated message buffer is full (loaded with a message
due for transmission).
1 = The associated message buffer is empty (not scheduled).
WARNING: To ensure data integrity, no registers of the transmit buffers should be written
to while the associated TXE flag is cleared.
NOTE: The CTFLG register is held in the reset state if the SFTRES bit CMCR0 is set.
17.13.9 msCAN12 Transmitter Control Register (CTCR)
Bit 7
0
6
ABTRQ2
0
5
ABTRQ1
0
4
ABTRQ0
0
3
0
2
TXEIE2
0
1
TXEIE1
0
Bit 0
TXEIE0
0
CTCR
$0107
RESET
R
W
0
0
ABTRQ2 – ABTRQ0 — Abort Request
The CPU sets an ABTRQx bit to request that a scheduled message
buffer (TXEx = 0) shall be aborted. The msCAN12 grants the request
if the message has not already started transmission, or if the
transmission is not successful (lost arbitration or error). When a
message is aborted the associated TXE and the Abort Acknowledge
flag (ABTAK, see msCAN12 Transmitter Flag Register (CTFLG)) are
set and an TXE interrupt is generated if enabled. The CPU cannot
reset ABTRQx. ABTRQx is cleared implicitly whenever the
associated TXE flag is set.
0 = No abort request.
1 = Abort request pending.
Advance Information
314
68HC(9)12D60 — Rev 4.0
MSCAN Controller
MOTOROLA
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