Is it RS485 supported with Ti sitara am335x Sk?

vijayan

Hi Everyone,

I want to use RS485 on TI sitra AM335x sk. I didnt find any serial port (UART) in this board to implement RS485 communication.

So my question is
1. Is it possible to use RS485 communication in TI sitara Am335s sk?
2. How can I use/implement RS485 communication ?

Please suggest me your valuable information.
Awaiting for your reply.

Thank you.
Regards,
Vijay

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

The AM335X Starter Kit has no external serial ports. There is a Zigbee header, J11, on which UART2 RXD/TXD signals are available with 3.3V levels. You can find the Starter Kit schematics here: processors.wiki.ti.com/.../AM335x_StarterKit_Board_Design_Files

0 vijayan over 8 years ago in reply to Biser Gatchev-XID

Prodigy 50 points

Hi ,

Thanks for your information. I think, implementing RS485 over UART is possible. But how can i implement RS485 support on AM335X UART ? is it need any patch work or anything else ? can you help me ?

Once again thanks for your replies.

0 Biser Gatchev-XID over 8 years ago in reply to vijayan

TI__Guru**** 393215 points

What software are you using?

0 vijayan over 8 years ago in reply to Biser Gatchev-XID

Prodigy 50 points

I am not getting what you mean software. But I am using timesys SDK and Kernel Version (3.14) .

Regards,
Vijay

0 Yordan Kovachev over 8 years ago in reply to vijayan

TI__Guru**** 161600 points

Hi Vijay,

Sorry for the delayed response.

Yes it is possible, to use RS485. Have a look at the omap-serial driver in the official TI SDK kernel (v3.14.43). Have in mind that 3.14 kernel has transitioned to 8250 driver, and I am not sure that it supports RS485 without any modifications, you may need to revert to omap-serial.

Best Regards,
Yordan

0 Stuart Baker over 8 years ago in reply to Yordan Kovachev

TI__Genius 10270 points

I certainly understand wanting to update our serial drivers, however, the fact that the 8250 driver does not support RS-485 is a major limitation. I just spent about 8 hours trying to debug why my RS-485 port worked fine until I updated to the latest 2.00.01.07 kernel. Turns out I had to disable the 8250 device driver platform and enable the old omap_serial device drivers in the kernel config. I'm now up and running.

Ideally, RS-485 support should be added to the 8250 device driver. In the meantime, I suggest the following change for future releases:

Add back in the omap_serial driver (we can keep the 8250 driver) to the default kernel configuration. Remove .compatible = "ti,omap3-uart" from the 8250_omap driver. In this way, device tree can pull the 8250 driver by default and the user can override the choice in their board specific device tree files. Also, document on the UART wiki page.

Thanks,
Stuart

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Is it RS485 supported with Ti sitara am335x Sk?