Trouble setting UART CTS pin as GPIO on CC6UL

Embedded Devices Linux
1

Hi,

I’m using the Digi CC6ULSBC Pro dev board and trying to configure J29 pin 9(UART3_CTS) as a GPIO. I have added the pin mux setting into the iomuxc node of the device tree and disabled UART3 in the device tree so it doesn’t conflict. Alternatively, I’ve tried not fully disabling UART3, but just configuring it for 2 wire UART function (no RTS/CTS function).
I’m unable to set the GPIO using the sysfs Linux utilities or gpioset.
I also unable to set UART2_CTS to gpio function, however, I am able to set pin 11 for example (UART2_TX), and ECSPI1 lines as GPIO with similar methods. It seems like it’s related to “CTS” function pins, thought that seems strange.

Can you offer any insights?
Thanks,
Christine

2

please use Smart IOMUX tool to figure out hardware configuration and generate proper device tree snapshots:
https://ftp1.digi.com/support/smartiomux/index.html

UART3_CTS is GPIO1_IO26
so in the tool make sure you configure UART3 as 2 pin interface (which it is by default). Then you should be able to add GPIO and select GPIO1_IO26 from the dropdown if it is not used by anything else.
However, by taking a quick look at other functions it becomes apparent that this pin is actually used by CAN_TX in the default device tree and not by UART_CTS. So please disable CAN if you do not need it and want to use this GPIO.