Pin mapping option for Carrier board design
Added by Zhe Ji over 10 years ago
Hi,
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?
Thank You!
Zhe
Replies (3)
RE: Pin mapping option for Carrier board design - Added by Jonathan Cormier over 10 years ago
Have you looked at this wiki page?
Pin Out
RE: Pin mapping option for Carrier board design - Added by Zhe Ji over 10 years ago
I see. Thank you.
And how am I be able to change them?
Zhe
RE: Pin mapping option for Carrier board design - Added by Jonathan Cormier over 10 years ago
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.
U-boot¶
In u-boot the pinmux configs are defined in the board/cl/mityarm335x/mux.c file.
http://support.criticallink.com/gitweb/?p=u-boot-mityarm-335x.git;a=blob;f=board/cl/mityarm335x/mux.c;h=254cad2b872fd93d0d94c088c82018c0df1c8224;hb=refs/heads/u-boot-2013.10
These definitions are then used in the board/cl/mityarm335x/som.c file.
http://support.criticallink.com/gitweb/?p=u-boot-mityarm-335x.git;a=blob;f=board/cl/mityarm335x/som.c;h=492b3774e44c6b9c7fdd7a1f2890d72860b1e823;hb=refs/heads/u-boot-2013.10
Kernel¶
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.
http://support.criticallink.com/gitweb/?p=linux-mityarm-335x.git;a=blob;f=arch/arm/mach-omap2/baseboard-mityarm335x-devkit.c;h=65d594c62a960ea07d447592e1282daf03609280;hb=refs/heads/mityarm-linux-v3.2#l130
Pinmuxes for devices on the SOM are located in the board-mityarm335x file.
http://support.criticallink.com/gitweb/?p=linux-mityarm-335x.git;a=blob;f=arch/arm/mach-omap2/board-mityarm335x.c;h=038558e1e707ff5fe076940e426b0fe86e8272af;hb=refs/heads/mityarm-linux-v3.2
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.
http://support.criticallink.com/gitweb/?p=linux-mityarm-335x.git;a=blob;f=arch/arm/mach-omap2/mux33xx.c;h=d45e440952f400580a2a9f7531df6c0387dfaf2c;hb=refs/heads/mityarm-linux-v3.2
