In order to check if all is ok you can use the wiringpi library and in particular Or using the layer meta-raspberrypi you can set it via the RPI_EXTRA_CONFIG The simplest way (with a modern firmware) is to use the last option: in my case I canĪdd directly in the config.txt the following lines gpio=22-27=a4 create a device driver and move the pins using it.There are several options to go with to set the desired pins, each one needs (but the first one)Ī recent version of the firmware (you can see the version of your system using vcgencmd version) It directly to modify the registers is a pain in the ass. The chip of the raspberry pi has 54 pins configurable via 41 32-bit registers the startĪddress is different between board models, for a pi zero is 0x7e200000 but to use If you don't have already u-boot compiled you can use Yocto via these variables PREFERRED_PROVIDER_virtual / bootloader = "u-boot" KERNEL_IMAGETYPE = "zImage" KERNEL_BOOTCMD = "bootz"īoot.cmd that is obtained compiling boot.scr fdt addr $ GPIOsįor future use I want to set the pins needed to use JTAG with the board. Take in mind that some document uses fdt_addr_r instead of the mainline's fdt_addr. The address is passed as environment variable in u-boot. The complicated thing that happens with this device is that the start.elf prepareĪlready the fdt ( flat device tree) at a specific address and doesn't need to be loaded from the cmdline.txt instead contains the arguments for the kernel.Ĭmdline.txt dwc_otg.lpm_enable=0 console=serial0,115200 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait console=tty0 This is achievable renaming accordingly the file or changing the right variable (named kernel) Kernel.img is usually the linux kernel, we want to substitute it with u-boot.
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