Chapter 16 Freescale’s Scalable Controller Area Network (S12MSCANV3)
MC9S12XE-Family Reference Manual , Rev. 1.19
620
Freescale Semiconductor
16.3.2.10 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).
Read: Anytime
Write: Unimplemented for ABTAKx flags
Table 16-14. 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 16.3.2.7, “MSCAN Transmitter Flag Register (CANTFLG)
”) and abort acknowledge flags (ABTAK, see
Section 16.3.2.10, “MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)
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
7
6
5
4
3
2
1
0
R
0
0
0
0
0
ABTAK2
ABTAK1
ABTAK0
W
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 16-13. MSCAN Transmitter Message Abort Acknowledge Register (CANTAAK)
Table 16-15. 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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