Hardware Reference
In-Depth Information
MSCAN T
RANSMITTER
I
NTERRUPT
E
NABLE
R
EGISTER
(CAN
X
TIER)
The contents of this register are shown in Figure 13.24.
7
6
5
4
3
2
1
0
Reset value
= 0x00
TXEIE1
0
0
0
0
0
TXEIE2
TXEIE0
TXEIE2
,
TXEIE0: transmitter k (
k
= 0,1, or 2) empty interrupt enable
0 = disable interrupt from this buffer.
1 = a transmitter empty event causes a transmitter empty interrupt request.
Figure 13.24
■
MSCAN transmitter interrupt enable register (CAN
x
TIER,
x
5
0, 1, 2, 3, or 4)
MSCAN T
RANSMITTER
M
ESSAGE
A
BORT
R
EQUEST
R
EGISTER
(CAN
X
TARQ)
When the application has a high-priority message to be sent but cannot find any empty trans-
mit buffer to use, it can request to abort the previous messages that have been scheduled for trans-
mission. The application can request to abort the message in any one of the transmit buffers. This is
done via the CAN
x
TARQ register. The contents of this register are shown in Figure 13.25.
7
6
5
4
3
2
1
0
Reset value
= 0x00
0
0
0
0
0
ABTRQ2
ABTRQ1
ABTRQ0
ABTRQ2
,
ABTRQ0: abort transmit request k (
k
= 0,1, or 2)
0 = no abort request.
1 = abort request pending.
Figure 13.25
■
MSCAN transmitter message abort request register (CAN
x
TARQ,
x
5
0, 1, 2, 3, or 4)
MSCAN T
RANSMIT
M
ESSAGE
A
BORT
A
CKNOWLEDGE
R
EGISTER
(CAN
X
TAAK)
A message that is being transmitted cannot be aborted. Only those messages that have not
been transmitted can be aborted. MSCAN answers the abort request by setting or clearing the
associated bits in this register. The contents of this register are shown in Figure 13.26.
7
6
5
4
3
2
1
0
Reset value
= 0x00
0
0
0
0
0
ABTAK2
ABTAK1
ABTAK0
ABTAK2
,
ABTAK0: abort transmit k (
k
= 0,1, or 2) acknowledge
0 = the message was not aborted.
1 = the message was aborted.
Figure 13.26
■
MSCAN transmitter message abort acknowledge register (CAN
x
TAAK,
x
5
0, 1, 2, 3, or 4)
MSCAN T
RANSMIT
B
UFFER
S
ELECTION
(CAN
X
TBSEL)
This register allows the selection of the transmit message buffer, which will then be acces-
sible in the CAN
x
TXFG register space. The contents of this register are shown in Figure 13.27.
The lowest-numbered bit that is set makes the respective transmit buffer accessible to the user.
For example, the combination TX1 5 1 and TX0 5 1 selects transmit buffer 0, and the combina-
tion TX1 5 1 and TX0 5 0 selects transmit buffer TX1.
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