1How to Update U-Boot on Pico-imx6ul board 2----------------------------------------- 3 4Required software on the host PC: 5 6- imx_usb_loader: https://github.com/boundarydevices/imx_usb_loader 7 8- dfu-util: http://dfu-util.sourceforge.net/releases/ 9 10Build U-Boot for Pico: 11 12$ make mrproper 13$ make pico-imx6ul_defconfig 14$ make 15 16This will generate the U-Boot binary called u-boot.imx. 17 18Put pico board in USB download mode (refer to the document 19http://www.wandboard.org/images/hobbit/hobbitboard-imx6ul-reva1.pdf page 15) 20 21Connect a USB to serial adapter between the host PC and pico 22 23Connect a USB cable between the OTG pico port and the host PC 24 25Open a terminal program such as minicom 26 27Copy u-boot.imx to the imx_usb_loader folder. 28 29Load u-boot.imx via USB: 30 31$ sudo ./imx_usb u-boot.imx 32 33Then U-Boot should start and its messages will appear in the console program. 34 35Use the default environment variables: 36 37=> env default -f -a 38=> saveenv 39 40Run the DFU command: 41=> dfu 0 mmc 0 42 43Transfer u-boot.imx that will be flashed into the eMMC: 44 45$ sudo dfu-util -D u-boot.imx -a boot 46 47Then on the U-Boot prompt the following message should be seen after a 48successful upgrade: 49 50#DOWNLOAD ... OK 51Ctrl+C to exit ... 52 53Remove power from the pico board. 54 55Put pico board into normal boot mode 56 57Power up the board and the new updated U-Boot should boot from eMMC. 58