We are developping a carier board for AM62 Solo module, we need 2 separate RS485 (Modbus) interface, in Toradex Pinout Designer we can use UART2 (RX/TX/RTS) no problem, but not UART 1 for some conflict, so we plan to use UART7 for the second RS485 bus HOWEVER when reading chapter 2.10.2.3 of Verdin Carrier Board design guide, it is written “The RTS signal is only available on the UART_1 and UART_2 as a Verdin standard interface.” could you clarify this sentence please ? and confirm we can use or not UART7 as second RS485 port ?
Hi, I’m the Toradex AI Assistant. The Toradex Support team will follow up with you shortly!
Did you like my answer?
Hello,
Thank you for reaching out with your question about implementing RS485 interfaces on the AM62 Solo module. The Verdin Carrier Board Design Guide indicates that the RTS (Request to Send) signal, essential for RS485 communication, is only available on UART1 and UART2 as standard interfaces. This is because the RTS signal is typically used to control the direction of data flow in RS485 communication.
If you wish to use UART7 for RS485, you will need to manage the direction control without the RTS signal. One approach is to implement software-based RTS control by manually toggling a GPIO pin to simulate the RTS signal. This method requires additional software development to ensure timely switching between transmit and receive modes.
Alternatively, you might consider using an external RS485 transceiver that can handle direction control independently of the RTS signal. Some transceivers offer built-in automatic direction control, which could simplify your design.
In summary, while UART7 can be used for RS485, addressing the lack of RTS signal through software solutions is necessary to ensure proper communication.
Best regards,
Toradex AI Assistant.
Please, also check if these links can help you solve your problem:
A standard interface is available on every module in its family, which, for the Verdin modules, are defined in the Verdin Family Specification.
When we say that RTS is only available as standard interface on UART_1 and UART_2, we are assuring that every module in the Verdin family will have RTS signals available on those pins.
You may find pins in the SoM that can also act (alternate function) as RTS for other UART instances, although they are “module-specific”, meaning that this functionality is not family-standard (so only applicable to the specific product).
Quickly looking through the AM62 datasheet I found the following UART instances that have RTS functionality available in the AM62 connector:
UART0 (UART_3 in Verdin Spec)
UART1 (UART_1 in Verdin Spec)
UART2
UART3
UART5
UART6
MCU_UART0 (UART_4 in Verdin Spec)
WKUP_UART0 (UART_2 in Verdin Spec)
You may, for example, use AM62’s UART0 (known in the Verdin specification as UART_3) with the RTS on pin 93 (Verdin’s I2C_4_CSI_SDA), so, in theory, it should be capable of RS485 operation.