Analog Devices ADSP-BF506F Hardware Reference Manual page 744

Functional Operation
If one of the counters exceeds 255 (that is, when the 8-bit counters over-
flow), the CAN module is disconnected from the bus. It goes into bus off
mode and the CAN error bus off mode (
ware intervention is required to recover from this state.
Table 17-3. CAN Error Level Description
Level
Error Active
Error Passive
Bus Off
In addition to these levels, the CAN module also provides a warning
mechanism, which is an enhancement to the CAN specification. There are
separate warnings for transmit and receive. By default, when one of the
error counters exceeds 96, a warning is signaled and is represented in the
register by either the CAN receive warning flag (
CAN_STATUS
transmit warning flag (
grammed using the error warning register,
available on page
Additionally, interrupts can occur for all of these levels by unmasking
them in the global CAN interrupt mask register (
on page 17-47. The interrupts include the bus off interrupt (
error-passive interrupt (
and the error warning transmit interrupt (
17-32
Condition
Transmit and receive error
counters 128
Transmit or receive error
counters  128, but  256
Transmit or receive error
counters  256
) bits. The error warning level can be pro-
WT
17-84.
), the error warning receive interrupt (
EPIM
ADSP-BF50x Blackfin Processor Hardware Reference
) bit is set in
EBO CAN_STATUS
Description
This is the initial condition level. As
long as errors stay below 128, the
node will drive active error flags dur-
ing error frames.
Errors have accumulated to a level
which requires the node to drive pas-
sive error flags during error frames.
CAN module goes into bus off mode
. More information is
CAN_EWR
) shown
CAN_GIM
).
EWTIM
. Soft-
) or CAN
WR
), the
BOIM
),
EWRIM