$ make pico-imx6ul_defconfig
$ make
-This will generate the U-Boot binary called u-boot.imx.
+This generates the SPL and u-boot.img binaries.
+
+1. Loading U-Boot via USB Serial Download Protocol
+
+Note: This method is convenient for development purposes.
+If the eMMC has already a U-Boot flashed with DFU support then
+the user can go to step 2 below in order to update U-Boot.
Put pico board in USB download mode (refer to the document
http://www.wandboard.org/images/hobbit/hobbitboard-imx6ul-reva1.pdf page 15)
Open a terminal program such as minicom
-Copy u-boot.imx to the imx_usb_loader folder.
+Copy SPL and u-boot.img to the imx_usb_loader folder.
+
+Load the SPL binary via USB:
-Load u-boot.imx via USB:
+$ sudo ./imx_usb SPL
-$ sudo ./imx_usb u-boot.imx
+Load the u-boot.img binary via USB:
+
+$ sudo ./imx_usb u-boot.img
Then U-Boot should start and its messages will appear in the console program.
=> env default -f -a
=> saveenv
+2. Flashing U-Boot into the eMMC
+
Run the DFU command:
=> dfu 0 mmc 0
-Transfer u-boot.imx that will be flashed into the eMMC:
+Flash SPL and u-boot.img into the eMMC running the following commands on a PC:
+
+$ sudo dfu-util -D SPL -a spl
-$ sudo dfu-util -D u-boot.imx -a boot
+$ sudo dfu-util -D u-boot.img -a u-boot
Then on the U-Boot prompt the following message should be seen after a
successful upgrade: