Scalable Controller Area Network (S12MSCANV3)
MC9S12G Family Reference Manual Rev.1.27
586 NXP Semiconductors
18.3.2.10 MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)
The CANTAAK register indicates the successful abort of a queued message, if requested by the
appropriate bits in the CANTARQ register.
NOTE
The CANTAAK register is held in the reset state when the initialization
mode is active (INITRQ = 1 and INITAK = 1).
18.3.2.11 MSCAN Transmit Buffer Selection Register (CANTBSEL)
The CANTBSEL register allows the selection of the actual transmit message buffer, which then will be
accessible in the CANTXFG register space.
Table 18-15. CANTARQ Register Field Descriptions
Field Description
2-0
ABTRQ[2:0]
Abort Request — The CPU sets the ABTRQx bit to request that a scheduled message buffer (TXEx = 0) be
aborted. The MSCAN 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 (see
Section 18.3.2.7, “MSCAN Transmitter Flag Register (CANTFLG)”) and abort acknowledge flags (ABTAK, see
Section 18.3.2.10, “MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)”) are set and a
transmit interrupt occurs if enabled. The CPU cannot reset ABTRQx. ABTRQx is reset whenever the associated
TXE flag is set.
0 No abort request
1 Abort request pending
Module Base + 0x0009 Access: User read/write
1
1
Read: Anytime
Write: Unimplemented
76543210
R0 0 0 0 0 ABTAK2 ABTAK1 ABTAK0
W
Reset:00000000
= Unimplemented
Figure 18-13. MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)
Table 18-16. CANTAAK Register Field Descriptions
Field Description
2-0
ABTAK[2:0]
Abort Acknowledge — This flag acknowledges that a message was aborted due to a pending abort request
from the CPU. After a particular message buffer is flagged empty, this flag can be used by the application
software to identify whether the message was aborted successfully or was sent anyway. The ABTAKx flag is
cleared whenever the corresponding TXE flag is cleared.
0 The message was not aborted.
1 The message was aborted.
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