AN2283 Freescale Semiconductor / Motorola, AN2283 Datasheet - Page 37

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

Transmitter Error
Passive Interrupt
Routine
Bus Off Interrupt
MOTOROLA
Motorola Scalable Controller Area Network (MSCAN) Interrupts
The Transmitter Error Passive Interrupt tells the software driver that the node
is in the error passive state, and the TEC value is in the range
128 <= REC <= 255, at which point the TERRIF (Transmitter Error Passive
Interrupt Flag) in CRFLG is set. To enable the Transmitter Error Passive
Interrupt, set the TERRIE (Transmitter Error Passive Interrupt Enable) bit in
CRIER.
To handle the Transmitter Error Passive Interrupt source:
The bus off interrupt tells the software driver that the node is in the bus off state,
and the TEC value is greater than 255. At this point the BOFFIF (bus off
interrupt flag) in CRFLG is set. To enable the Bus Off Interrupt, set the BOFFIE
(Bus Off Interrupt Enable) bit in CRIER. When the node is in the Bus Off State
it is not allowed to participate in bus communication because it has generated
too many transmit errors; therefore, disturbing communication between itself
and other nodes. After 128 occurrences of 11 consecutive recessive [1] bits
have been monitored on the bus the REC and TEC are reset to 0, and the node
returns to the error active state (No Warning/Error State).
3. Clear the Transmitter Warning Interrupt Enable (TWRNIE) bit in CRIER
4. Any additional interrupt handling code.
1. Clear the Transmitter Warning Interrupt Flag (TWRNIF) bit in CRFLG by
2. Next, set the Transmitter Warning Interrupt Enable (TWRNIE) bit in
3. Clear the Transmitter Error Passive Interrupt Enable (TERRIE) bit in
4. Any additional interrupt handling code.
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so that another Transmitter Warning Interrupt will not execute repeatedly
for the duration of this state (transmitter 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
transmitter warning state, where the TWRNIF was set.) These interrupt
flags remain set in a level sensitive manner as long as the setting
condition remains.
CRIER. The TWRNIE bit is cleared in the Transmitter Warning Interrupt
routine when the MSCAN transitions to the Transmitter Warning State.
CRIER so that another Transmitter Error Passive Interrupt will not
execute repeatedly for the duration of this state (transmitter error
passive state). This is due to the fact that interrupt flags remain set in a
level sensitive manner as long as the setting condition remains.
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Figure
24, CRFLG utilizes the
Error Interrupts Overview
AN2283/D
37