Pin mapping option for Carrier board design
Added by Zhe Ji over 9 years ago
I am now designing a carrier board for MitySOM335.
In the design guide, it mentions:
The I2C1 and I2C2 interface signals/mux options cannot be changed as they are used for dedicated functions on the MityARM-335x module.
Is this pin 147 only?
Or they include pin 165,167,169,171,173,175, 183,185,187,191
Also, how would I be able to know which pin mux option is set, and how would I be able to change them?
Have you looked at this wiki page?
RE: Pin mapping option for Carrier board design - Added by Zhe Ji about 9 years ago
I see. Thank you.
And how am I be able to change them?
This depends on at which stage you want access to the pins. Both u-boot and the kernel make changes to the pin mux. If the device needs to be accessed while you in the u-boot bootloader then u-boot should set the pinmux. If not then the kernel can set it.
In u-boot the pinmux configs are defined in the board/cl/mityarm335x/mux.c file.
These definitions are then used in the board/cl/mityarm335x/som.c file.
For the kernel you will want to create your own baseboard file so you can add and remove stuff so that it matches your custom board. See Creating a custom baseboard
Heres a link to the devkit baseboard file in the kernel. There are several pin mux configs defined in this board.
Pinmuxes for devices on the SOM are located in the board-mityarm335x file.
The pinmux pins are defined in the mux33xx.c file. Note that TI has not filled in all possible pinmuxes so in the rare case you want to use a pin they haven't defined you might need to modify this file.