[Ovmsdev] Twizy / 500 kbps CAN lockups

[Mark Webb-Johnson]

Looking at the Microchip AN for this, and online calculators, this looks very complex.

The current numbers we use originally came from Michael Stegen. Not sure how he calculated them.

Michael J got it working in his 500kbps Volt/Ampera using BRGCON1=0x01 - so same settings as 1Mhz, but with a x2 prescaler. That seems a good solution and the approach should work also for 256kbps, 128kbps, etc.

You say that the CAN reception stops, and starts again by switching the car off+on. Does that also reset the OVMS module? Another possibility is that the Twizy go to sleep and stops transmitting on the can bus?

Regards, Mark.

On 3 Nov, 2012, at 3:54 AM, Michael Balzer <dexter at expeedo.de> wrote:

> During my tests I had two times some sort of a CAN lockup, i.e. everything worked except the CAN reception -- was fixed by switching the car off + on.
> 
> I'm not sure yet what caused that, it (of course) did not happen again since I included a first debug output of the RXERRCNT...
> 
> I saw the 1 mbps setup does not follow the intrepid timing calculator standard parameters but increases prop delay from 1 to 3 and decreases phase 1 from 5 to 3.
> 
> A similar change to the 500 kbps parameters though did not work with the Twizy.
> 
> Do you have any hints on debugging this?
> 
> My current setup for 500 kbps is:
> 
>    // 500 kbps -- tool recommendation + multisampling:
>    BRGCON1 = 0x00;
>    BRGCON2 = 0xFA;
>    BRGCON3 = 0x07;
> 
> Thanks,
> Michael
> 
> -- 
> Michael Balzer * Paradestr. 8 * D-42107 Wuppertal
> Fon 0202 / 272 2201 * Handy 0176 / 206 989 26
> 
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