Re: [Socketcan-users] AM335x CAN/D_CAN

[Wolfgang Grandegger <wg@grandegger.com>]

Hello,

I switched the discussion to the new Linux-CAN mailing list.

On 05/22/2012 05:50 PM, bruce bushby wrote:
> Greetings
> 
> I'm hoping a list member would be so kind as to offer some basic
> explanations of how one would use the CAN bus provided by AM335x. I
> understand Linux, but struggle with electronics.
> 
> I have read this discussion: http://comments.gmane.org/gmane.linux.can/1142
> What is the difference between C_CAN and D_CAN?

As I see it, the D_CAN is a more advanced variant of the C_CAN
controller. See also:

http://www.semiconductors.bosch.de/en/ipmodules/can/canipmodules/c_can/c_can.asp
http://www.semiconductors.bosch.de/en/ipmodules/can/canipmodules/d_can/d_can.asp

Patches to add D_CAN support to the Linux-CAN C_CAN driver have been
posted recently for mainline inclusion and are currently reviewed.

> http://www.spinics.net/lists/linux-omap/msg67538.html
> Does D_CAN have anything to do with mcp2515?

No, nothing apart from the fact that both are CAN controllers. The
mcp2515 is connected via SPI bus and from another company.

> In order to connect the am335x CAN line to a CAN bus, would I need to
> add a CAN transceiver?

Hardware-wise, yes.

> Is the am335x an "in memory CAN" ... ie I wouldn't need to worry about
> SPI bus performance?

Right. On the AM335x, the D_CAN controller is integrated into the SOC.
There is no SPI involved.

> Any explanations and help much appreciated!

Hope it's useful.

Wolfgang.