christian pellegrin wrote:
> Ditto for mcp251x but against mainline. Just a question I noted
> studying the error frames: it looks to me that there isn't an error
> frame saying "the situation is come back to normality" (I mean
> error-active). Is this normal or I'm just missing something?
I found this useful information in the AT91 CAN manual:
<begin quote>
• REC: Receive Error Counter
When a receiver detects an error, REC will be increased by one, except when the
detected error is a BIT ERROR while
sending an ACTIVE ERROR FLAG or an OVERLOAD FLAG.
When a receiver detects a dominant bit as the first bit after sending an ERROR
FLAG, REC is increased by 8.
When a receiver detects a BIT ERROR while sending an ACTIVE ERROR FLAG, REC is
increased by 8.
Any node tolerates up to 7 consecutive dominant bits after sending an ACTIVE
ERROR FLAG, PASSIVE ERROR FLAG or
OVERLOAD FLAG. After detecting the 14th consecutive dominant bit (in case of an
ACTIVE ERROR FLAG or an OVER-
LOAD FLAG) or after detecting the 8th consecutive dominant bit following a
PASSIVE ERROR FLAG, and after each
sequence of additional eight consecutive dominant bits, each receiver increases
its REC by 8.
After successful reception of a message, REC is decreased by 1 if it was
between 1 and 127. If REC was 0, it stays 0, and
if it was greater than 127, then it is set to a value between 119 and 127.
• TEC: Transmit Error Counter
When a transmitter sends an ERROR FLAG, TEC is increased by 8 except when
– the transmitter is error passive and detects an ACKNOWLEDGMENT ERROR
because of not detecting a
dominant ACK and does not detect a dominant bit while sending its
PASSIVE ERROR FLAG.
– the transmitter sends an ERROR FLAG because a STUFF ERROR occurred
during arbitration and should
have been recessive and has been sent as recessive but monitored as
dominant.
When a transmitter detects a BIT ERROR while sending an ACTIVE ERROR FLAG or an
OVERLOAD FLAG, the TEC will
be increased by 8.
Any node tolerates up to 7 consecutive dominant bits after sending an ACTIVE
ERROR FLAG, PASSIVE ERROR FLAG or
OVERLOAD FLAG. After detecting the 14th consecutive dominant bit (in case of an
ACTIVE ERROR FLAG or an OVER-
LOAD FLAG) or after detecting the 8th consecutive dominant bit following a
PASSIVE ERROR FLAG, and after each
sequence of additional eight consecutive dominant bits every transmitter
increases its TEC by 8.
After a successful transmission the TEC is decreased by 1 unless it was already
0.
<end qoute>
Wolfgang.
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