Controller Area Network (CAN) - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 654

MSCAN R ECEIVER I NTERRUPT E NABLE R EGISTER (CAN X RIER)
This register enables and disables all interrupts related to the CAN receiver. The contents
of this register are shown in Figure 13.22.

7 6 5 4 3 2 1 0

Reset value
= 0x00

WUPIE CSCIE RSTATE1 RSTATE0 TSTATE1 TSTATE0 OVRIE RXFIE

WUPIE: wake-up interrupt enable
0 = no interrupt request is generated from this event.
1 = a wake-up event causes a wake-up interrupt request.
CSCIE: CAN status change interrupt enable
0 = no interrupt request is generated from this event.
1 = a CAN status change event causes an error interrupt request.
RSTATE1 , RSTATE0: receiver status change interrupt enable
00 = do not generate any CSCIF interrupt caused by receiver state changes.
01 = generate CSCIF interrupt only if the receiver enters or leaves bus-off
state.
10 = generate CSCIF interrupt only if the receiver enters or leaves RxErr or
bus-off state.
11 = generate CSCIF interrupt on all state changes.
TSTATE1 , TSTATE0: transmitter status change interrupt enable
00 = do not generate any CSCIF interrupt caused by transmitter state changes.
01 = generate CSCIF interrupt only if the transmitter enters or leaves bus-
off state.
10 = generate CSCIF interrupt only if the transmitter enters or leaves bus-
off or TxErr state.
11 = generate CSCIF interrupt on all state changes.
OVRIE: overrun interrupt enable
0 = no interrupt request is generated from this event.
1 = an overrun event causes an error interrupt request.
RXFIE: receive buffer interrupt enable
0 = no interrupt request is generated from this event.
1 = a receive buffer full event causes a receiver interrupt request.

Figure 13.22 ■ MSCAN receiver interrupt enable register (CAN x RIER, x 5 0, 1, 2, 3, or 4)

MSCAN T RANSMITTER F LAG R EGISTER (CAN X TFLG)
The contents of this register are shown in Figure 13.23. Each of the three flags indicates
whether its associated transmit buffer is empty, and thus not scheduled for transmission. These
flags can be cleared by writing a 1 to them.

7 6 5 4 3 2 1 0

Reset value
= 0x07

0 0 0 0 TXE2 TXE1

0 TXE0

TXE2 , TXE0: transmitter buffer x ( x = 0,1, or 2) empty
0 = the associated message buffer is full (loaded with a message due for
transmission).
1 = the associated message buffer is empty.

Figure 13.23 ■ MSCAN transmitter flag register (CAN x TFLG, x 5 0, 1, 2, 3, or 4)