AN2283 Freescale Semiconductor / Motorola, AN2283 Datasheet - Page 32

• Manufacturer Part Number: AN2283
• Description: Scalable Controller Area Network (MSCAN)
• Manufacturer: Freescale Semiconductor / Motorola

AN2283/D
Receiver Warning
Interrupt
Receiver Error
Passive Interrupt
Routine
32
NOTE:
Motorola Scalable Controller Area Network (MSCAN) Interrupts
In summary, the REC increases by one for most RX errors, by eight on severe
RX errors, and decrements by one on a successful RX.
More than one rule may apply during a given message transfer.
The Receiver Warning Interrupt tells the software driver that the node is in the
error active state, and the REC value is in the range 96 <=< REC < 128. This
implements a recommendation in the CAN specification which gives the
application an indicator that there are issues on the bus before it reaches the
point that communication is affected. Once REC crosses into this range, the
RWRNIF (Receiver Warning Interrupt Flag) in CRFLG is set. To enable the
Receiver Warning Error Interrupt, set the RWRNIE (Receiver Warning Interrupt
Enable) bit in CRIER.
To handle the Receiver Warning Interrupt source:
The Receiver Error Passive Interrupt tells the software driver that the node is
in the Error Passive State, and that the REC value is in the range
128 <=< REC <= 255, at which point RERRIF in CRFLG is set. To enable the
Receiver Error Passive Interrupt Source, set RERRIE in CRIER.
To handle the Receiver Error Passive Interrupt source:
1. Clear the Receiver Error Interrupt Flag (RERRIF) bit in by writing a 1 to
2. Next, set the Receiver Error Passive Interrupt Enable (RERRIE) bit in
3. Clear the RWRNIE bit in CRIER so that another Receiver Warning
4. Any additional interrupt handling code.
1. Clear the Receiver Warning Interrupt Flag (RWRNIF) bit in CRFLG by
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it. (As mentioned in
operation). The reason is that this state can be entered from the
Receiver Error Passive State, where RERRIF was set. These interrupt
flags remain set in a level sensitive manner as long as the setting
condition remains.
CRIER. The RERRIE bit is cleared in the Receiver Error Passive
Interrupt routine when the MSCAN transitions to the Receiver Error
Passive State.
Interrupt will not execute repeatedly for the duration of this state
(Receiver Warning State). This is due to the fact that interrupt flags
remain set in a level sensitive manner as long as the setting condition
remains.
writing a 1 to it. (As mentioned in
exclusive OR operation). The reason is that this state is entered from the
Receiver Warning State, where RWRNIF was set. These interrupt flags
remain set in a level sensitive manner as long as the setting condition
remains.
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Figure
22, CRFLG utilizes the exclusive OR
Figure
23, CRFLG utilizes the
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