CAN - problem with TX Error Counter

Started by miruffer September 8, 2005
Hi,

I have the LPC-E2294 develpmentboard from olimex. The CAN-controllers
work fine, but if I plug off the CAN-cable the CAN-controller should
go into bus-off state, after the TX-ERROR Counter reachs 255.

The error interrupts works fine and in the "Interrupt and Capture
Register" the controller captured the "ACK Slot".

I look at the TX Error counter and it will be incremented correctly
until it reachs 128.

The "error warning interrupt" and the "passive state interrupt" occurs
correctly and the bits will be set in ICR. After TX-ERR-CNT reachs 128
the ICR only shows an Bus Error and the TX-ERR-CNT holds its value.

When I plug on the bus-cable, the transmission of messages continue
correctly and the TX-ERR-CNT will be decremented until 0.

Now my question. Why does the controller stops incrementing the
TX-ERR-Counter at 128?

thanks and regards,

miru



An Engineer's Guide to the LPC2100 Series

--- In lpc2000@lpc2..., "miruffer" <miruffer@y...> wrote:
> Now my question. Why does the controller stops incrementing the
> TX-ERR-Counter at 128?
>

Hi miru,

a CAN node in error passive detecting an Acknowledgement Error does
not increase the error counter according to the CAN specification.

Regards
Gerhard


--- In lpc2000@lpc2..., "gerhard_uttenthaler"
<gerhard.uttenthaler@g...> wrote:
> --- In lpc2000@lpc2..., "miruffer" <miruffer@y...> wrote:
> > Now my question. Why does the controller stops incrementing the
> > TX-ERR-Counter at 128?
> >
>
> Hi miru,
>
> a CAN node in error passive detecting an Acknowledgement Error does
> not increase the error counter according to the CAN specification.
>
> Regards
> Gerhard

The answer is so simple! Thank you!

miru