topic Re: The GPIO Pin about CAN bus in i.MX Processors

The GPIO Pin about CAN bus

Ushnek — Thu, 17 May 2012 01:38:18 GMT

Hi All,

In my test, the CAN message is sent by "cansend" command but it still not transmitted. I can observe this message in the message buffer memory by realview ICE.

I saw 3 PIN(CAN_STBY,CAN_EN,CAN_NERR) in iMX53 ARD schematic.

Could somebody tell me what functions in those PIN?

Are there any effect, if we don't make those PIN?(especially NERR GPI PIN)

Thanks.

Re: The GPIO Pin about CAN bus

OscarLuna — Mon, 21 May 2012 17:02:24 GMT

Hello Ken,

1) The CAN_NERR pin reports any static errors, flags and wake-ups to the processor (IMX53) depending on devices operating state.

2) The CAN_STBY pin is used to put the CAN transceiver into the standby mode. This mode allows to reduce the consumption of the transceiver during inactivity.

3) The CAN_EN pin is used to enable/disable the CAN transceiver.

The CAN_STBY and CAN_EN pins are definitely used by the Flexcan driver in the IMX53. These two pins are the most important of the three mentioned above.

Which version of the BSP are you using?

Hope this information helps!

Best regards.

Re: The GPIO Pin about CAN bus

Ushnek — Tue, 22 May 2012 10:47:24 GMT

Hi Oscar,

Thank for your reply.

I use package "L2.6.35_11.09.01" and we use this BSP on our EVB board with imx53.

I modified PIN definitions in "mx53_loco.c" to fit our board but I don't very understand these GPIO PIN about CAN bus.

Yours sincerely.

Re: The GPIO Pin about CAN bus

OscarLuna — Tue, 22 May 2012 20:23:50 GMT

Hi Ken,

For a better clarification about the ERR pin of th eMC33902 CAN transceiver, please see the below link:

http://cache.freescale.com/files/analog/doc/data_sheet/MC33902.pdf?fsrch=1&sr=1

Just Iet me know if the document does not clarify your doubts.

With regards your problem sending CAN frames, could you please check the STANBY pin in your board? What is the current level of the line?

Hope this information helps.

Oscar

Ken Hsu said:

Hi Oscar,
Thank for your reply.
I use package "L2.6.35_11.09.01" and we use this BSP on our EVB board with imx53.
I modified PIN definitions in "mx53_loco.c" to fit our board but I don't very understand these GPIO PIN about CAN bus.
Yours sincerely.

Re: The GPIO Pin about CAN bus

Ushnek — Fri, 25 May 2012 03:12:22 GMT

Dear Oscar,

Thank you so much!

It is very useful for me.

Oscar Luna said:

Hi Ken,
For a better clarification about the ERR pin of th eMC33902 CAN transceiver, please see the below link:
http://cache.freescale.com/files/analog/doc/data_sheet/MC33902.pdf?...
Just Iet me know if the document does not clarify your doubts.
With regards your problem sending CAN frames, could you please check the STANBY pin in your board? What is the current level of the line?
Hope this information helps.
Oscar

Ken Hsu said:
Hi Oscar,
Thank for your reply.
I use package "L2.6.35_11.09.01" and we use this BSP on our EVB board with imx53.
I modified PIN definitions in "mx53_loco.c" to fit our board but I don't very understand these GPIO PIN about CAN bus.
Yours sincerely.