16.6.4 Stamping Message
The capture of the timer value is done in the MOb which receives or sends the frame. All managed MOb are stamped, the
stamping of a received (sent) frame occurs on RxOk (TXOK).
16.7 Error Management
16.7.1 Fault Confinement
The CAN channel may be in one of the three following states:
●
Error active (default):
The CAN channel takes part in bus communication and can send an active error frame when the CAN macro detects
an error.
●
Error passive:
The CAN channel cannot send an active error frame. It takes part in bus communication, but when an error is
detected, a passive error frame is sent. Also, after a transmission, an error passive unit will wait before initiating
further transmission.
●
Bus off:
The CAN channel is not allowed to have any influence on the bus.
For fault confinement, a transmit error counter (TEC) and a receive error counter (REC) are implemented. BOFF and ERRP
bits give the information of the state of the CAN channel. Setting BOFF to one may generate an interrupt.
Figure 16-12. Line Error Mode
Reset
ERRP = 0
BOFF = 0
Error
Active
TEC > 127
128 occurrences
of 11 consecutive
recessive bit
or
Rec 127
TEC ≤ 127
and
Rec ≤ 127
ERRP = 1
BOFF = 0
ERRP = 1
BOFF = 0
Error
Bus
Off
Passive
TEC > 255
Interrupt BOFFIT
Note:
More than one REC/TEC change may apply during a given message transfer.
ATmega16/32/64/M1/C1 [DATASHEET]
153
7647O–AVR–01/15
MICROCHIP [ MICROCHIP ]
