AM625: About rs-485

hao teng

Part Number: AM625

Tool/software:

I was recently debugging a 485, and my 485 has a transmit/receive enable pin.The default state allows data to be received, and the enable pin is flipped when data is sent.I found the following link configuration in the forum.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/527378/am335x-gpio-based-rts-for-rs-485

I have two questions.

First, is this RTS pin fixed? Can I bind it to other GPIO pins in the device tree?

Second, is the level change of this pin automatically changed when sending data? Is it changed inside the chip or implemented by the driver?

thanks！！

over 1 year ago

0 Vaibhav Kumar over 1 year ago

TI__Mastermind 48287 points

Hi,

hao teng said:
Is it changed inside the chip or implemented by the driver?

Which drivers are you referring to here? The MCU PLUS SDK or the PROCESSOR SDK LINUX ?

Regards,

Vaibhav

0 hao teng over 1 year ago in reply to Vaibhav Kumar

Intellectual 370 points

Hi,

I am using AM62, SDK8.06-rt-linux, and the driver is 8250

0 Vaibhav Kumar over 1 year ago in reply to hao teng

TI__Mastermind 48287 points

Hello,

I have reassigned this query to the correct expert, you can expect responses in sometime.

Regards,

Vaibhav

+1 Bin Liu over 1 year ago

TI__Guru**** 171431 points

Hi Hao,

hao teng said:
First, is this RTS pin fixed? Can I bind it to other GPIO pins in the device tree?

Second, is the level change of this pin automatically changed when sending data? Is it changed inside the chip or implemented by the driver?

The kernel UART driver supports both native RTS pin or any GPIO pin for RS-485 direction control.

When the native RTS pin is used, the level is directly controlled by the UART controller, no software involved. (Please note that in SDK9.x, the native RTS pin level change is controlled by UART driver, it is not hardware controlled.)

While if a GPIO pin is used (by defining "rts-gpios" property in the UART node in devicetree), the level change is controlled by the kernel UART driver.

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AM625: About rs-485