Verdin iMX8MM RS-485

Does the iMX8M Mini have driver direction control support for RS-485 built in to the CTS_B signals like the iMX8M Plus? Or should I assign a GPIO signal?


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The i.MX8M Mini UART indeed supports RS-485 auto RTS for controlling the direction of the RS-485 transceiver, similar to the iMX8M Plus. This feature allows for automatic control of the RS-485 transceiver direction without the need for additional GPIOs to manage the transmit and receive modes. The CTS_B (Clear To Send) signal is typically used in RS-232 communications for flow control but can be repurposed in RS-485 implementations for direction control, leveraging the UART’s built-in support for RS-485.

To utilize this feature, ensure that your Linux kernel configuration includes support for the RS-485 mode in the UART driver and that you correctly configure the UART interface for RS-485 operation, specifying the appropriate pins for your application. This configuration can typically be done through the device tree or at runtime via sysfs for the Linux kernel.

If you’re working with the Verdin iMX8M Mini and planning to use RS-485 communication, it’s advisable to review the UART and RS-485 sections of the i.MX8M Mini reference manual for detailed information on configuring and using these features. This ensures that you can leverage the built-in RS-485 support effectively without the need for additional external signals for direction control.

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Please, also check if these links can help you solve your problem:

UART (Linux) | Toradex Developer Center.

Thank you. If there are pin conflicts with the CTS_B pin, can I alternatively use a GPIO?

Hi @cwea Please check this article for the details.