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 generates the SPL and u-boot.img binaries. 17 181. Loading U-Boot via USB Serial Download Protocol 19 20Note: This method is convenient for development purposes. 21If the eMMC has already a U-Boot flashed with DFU support then 22the user can go to step 2 below in order to update U-Boot. 23 24Put pico board in USB download mode (refer to the document 25http://www.wandboard.org/images/hobbit/hobbitboard-imx6ul-reva1.pdf page 15) 26 27Connect a USB to serial adapter between the host PC and pico 28 29Connect a USB cable between the OTG pico port and the host PC 30 31Open a terminal program such as minicom 32 33Copy SPL and u-boot.img to the imx_usb_loader folder. 34 35Load the SPL binary via USB: 36 37$ sudo ./imx_usb SPL 38 39Load the u-boot.img binary via USB: 40 41$ sudo ./imx_usb u-boot.img 42 43Then U-Boot should start and its messages will appear in the console program. 44 45Use the default environment variables: 46 47=> env default -f -a 48=> saveenv 49 502. Flashing U-Boot into the eMMC 51 52Run the DFU command: 53=> dfu 0 mmc 0 54 55Flash SPL and u-boot.img into the eMMC running the following commands on a PC: 56 57$ sudo dfu-util -D SPL -a spl 58 59$ sudo dfu-util -D u-boot.img -a u-boot 60 61Then on the U-Boot prompt the following message should be seen after a 62successful upgrade: 63 64#DOWNLOAD ... OK 65Ctrl+C to exit ... 66 67Remove power from the pico board. 68 69Put pico board into normal boot mode 70 71Power up the board and the new updated U-Boot should boot from eMMC. 72