AM4378: RS-485 interface

shigehiro tsuda

Part Number: AM4378

Hi,

Our customers need 4 ports of RS-485 interface.

We are investigating whether it can be normally controlled at the timing of RS-485 standard.
Which of the followings would you like?
① GPIO + UART
② GPU + ICSS GPIO + UART

Also please tell me if there are drivers and samples respectively.
· Linux
· PRU - ICSS

Best Regards,
Shigehiro Tsuda

over 6 years ago

0 Bin Liu over 6 years ago

TI__Guru**** 168631 points

Hi Shigehiro-san,

The Linux kernel UART driver seems support CTS/RTS pins for RS-485 standard, unfortunately we are unable to validate the function since we don't have any AM437x board which has RS-485 interface.

0 shigehiro tsuda over 6 years ago in reply to Bin Liu

Mastermind 9490 points

Hi Bin Liu,

Thank you for quick reply.

Should they use RTS/CTS instead of GPIO?
I understood that you can not check without a board that can be evaluated.
Do you have experience with the rs-485 interface using linux 's uart driver?

Best Regards,
Shigehiro tsuda

0 Bin Liu over 6 years ago in reply to shigehiro tsuda

TI__Guru**** 168631 points

Shigehiro-san,

I am not familiar with the linux implementation of rs-485, since we don't any a platform using it. But if you look at the uart driver
git.ti.com/.../8250_omap.c, line 714,715

rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U);

which configures the timing for rts in rs485, that is how I concluded the Linux driver uses RTS for RS-485.

0 shigehiro tsuda over 6 years ago in reply to Bin Liu

Mastermind 9490 points

Hi Bin Liu,

Thank you for quick reply.
I understand that the timing of RTS with the RS485 linux driver can adjust .

Best Regards,
Shigehiro Tsuda

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AM4378: RS-485 interface