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Chapter 10 Freescale’s Scalable Controller Area Network (S12MSCANV3)
MC9S12XDP512 Data Sheet, Rev. 2.17
Freescale Semiconductor
435
NOTE
TheCANTIERregisterisheldintheresetstatewhentheinitializationmode
is active (INITRQ = 1 and INITAK = 1). This register is writable when not
in initialization mode (INITRQ = 0 and INITAK = 0).
Read: Anytime
Write: Anytime when not in initialization mode
10.3.2.9
MSCAN Transmitter Message Abort Request Register (CANTARQ)
The CANTARQ register allows abort request of queued messages as described below.
NOTE
The CANTARQ register is held in the reset state when the initialization
modeisactive(INITRQ=1andINITAK=1).Thisregisteriswritablewhen
not in initialization mode (INITRQ = 0 and INITAK = 0).
Read: Anytime
Write: Anytime when not in initialization mode
Table 10-12. CANTIER Register Field Descriptions
Field
Description
2:0
TXEIE[2:0]
Transmitter Empty Interrupt Enable
0 No interrupt request is generated from this event.
1 A transmitter empty (transmit buffer available for transmission) event causes a transmitter empty interrupt
request.
7
6
5
4
3
2
1
0
R
0
0
0
0
0
ABTRQ2
ABTRQ1
ABTRQ0
W
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 10-12. MSCAN Transmitter Message Abort Request Register (CANTARQ)
Table 10-13. 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 10.3.2.7, “MSCAN Transmitter Flag Register (CANTFLG)
”) and abort acknowledge flags (ABTAK, see
Section 10.3.2.10, “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