Freescale’s Scalable Controller Area Network (S12MSCANV3)
Table 8-12. CANRIER Register Field Descriptions
Field
Description
7
Wake-Up Interrupt Enable
WUPIE(1)
0
1
No interrupt request is generated from this event.
A wake-up event causes a Wake-Up interrupt request.
6
CAN Status Change Interrupt Enable
CSCIE
0
1
No interrupt request is generated from this event.
A CAN Status Change event causes an error interrupt request.
5-4
Receiver Status Change Enable — These RSTAT enable bits control the sensitivity level in which receiver state
RSTATE[1:0] changes are causing CSCIF interrupts. Independent of the chosen sensitivity level the RSTAT flags continue to
indicate the actual receiver state and are only updated if no CSCIF interrupt is pending.
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. Discard other receiver state
changes for generating CSCIF interrupt.
10 Generate CSCIF interrupt only if the receiver enters or leaves “RxErr” or “bus-off”(2) state. Discard other
receiver state changes for generating CSCIF interrupt.
11 Generate CSCIF interrupt on all state changes.
3-2
Transmitter Status Change Enable — These TSTAT enable bits control the sensitivity level in which transmitter
TSTATE[1:0] state changes are causing CSCIF interrupts. Independent of the chosen sensitivity level, the TSTAT flags
continue to indicate the actual transmitter state and are only updated if no CSCIF interrupt is pending.
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. Discard other transmitter
state changes for generating CSCIF interrupt.
10 Generate CSCIF interrupt only if the transmitter enters or leaves “TxErr” or “bus-off” state. Discard other
transmitter state changes for generating CSCIF interrupt.
11 Generate CSCIF interrupt on all state changes.
1
Overrun Interrupt Enable
OVRIE
0
1
No interrupt request is generated from this event.
An overrun event causes an error interrupt request.
0
Receiver Full Interrupt Enable
RXFIE
0
1
No interrupt request is generated from this event.
A receive buffer full (successful message reception) event causes a receiver interrupt request.
1. WUPIE and WUPE (see Section 8.3.2.1, “MSCAN Control Register 0 (CANCTL0)”) must both be enabled if the recovery
mechanism from stop or wait is required.
2. Bus-off state is defined by the CAN standard (see Bosch CAN 2.0A/B protocol specification: for only transmitters. Because the
only possible state change for the transmitter from bus-off to TxOK also forces the receiver to skip its current state to RxOK,
the coding of the RXSTAT[1:0] flags define an additional bus-off state for the receiver (see Section 8.3.2.5, “MSCAN Receiver
Flag Register (CANRFLG)”).
8.3.2.7
MSCAN Transmitter Flag Register (CANTFLG)
The transmit buffer empty flags each have an associated interrupt enable bit in the CANTIER register.
S12P-Family Reference Manual, Rev. 1.13
Freescale Semiconductor
265
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