Yocto Recovery SD card
Variscite provides a recovery SD card image that can be used to install the pre-built U-Boot, Linux kernel and the file system into the internal storage of the SOM.
1 Download the recovery SD card image
Download the latest recovery SD card from Variscite's FTP server: ftp://customerv:Variscite1@ftp.variscite.com/VAR-SOM-MX7/Software/b2qt
Note: Some web browsers have removed FTP support. Please see our FTP wiki page.
The easiest way to download files from an FTP server using the Linux command line is to use wget:
$ wget ftp://customerv:Variscite1@ftp.variscite.com/VAR-SOM-MX7/Software/b2qt/dunfell-b2qt-5.4.85-mx7-v1.0.img.gz
2 Write the image to an SD card
Double check that the device is correct to avoid accidentally overwriting a different device and potentially damaging your existing operating system.
2.1 Using a Linux based host
Plug-in the SD card to your Linux host PC, run dmesg and see which device is added (i.e. /dev/sdX or /dev/mmcblkX)
$ sudo umount /dev/sdX?* $ zcat <image name>.img.gz | sudo dd of=/dev/sdX bs=1M && sync (Replace /dev/sdX with your actual device)
2.2 Using a Windows based host
- Download Win32 Disk Imager from: https://sourceforge.net/projects/win32diskimager/ and install it.
- Extract downloaded <image name>.img.gz file to get <image name>.img (using 7-Zip for example)
- Insert your SD card into your PC.
No need to format the SD card before writing the image to it, as the card will be formatted once it will be flashed.
- Run the file named Win32DiskImager.exe (in Windows 7, 8 and 10 we recommend that you right-click this file and choose “Run as administrator”).
- If the SD card (Device) you are using isn’t found automatically. Click on the drop down box and select it
- In the Image File box, choose the <image name>.img file you have extracted previously
- Click Write
- After a few minutes, you receive a notification that your SD has been created successfully.
2.3 Using a Mac OS X host
Use the dd Utility for MAC OS X to flash .img files to your SD card
3 Recover NAND flash/eMMC
- Power-off the board.
- Insert the SD card into the SD card slot of the carrier board (DVK)
- Make sure the Boot Mode is set to SD card: see section
- Power up the board - it will boot into Linux from the SD card
3.1 Flash from command line
- Login as root (no password)
- From Linux command line, run the following script:
# install_yocto.sh - Install Yocto (Boot2Qt) to the SOM's internal storage (follow the printed instructions)
3.2 SD card image file tree
/opt/images/ └── Yocto ├── imx7d-var-som-emmc.dtb ├── imx7d-var-som-nand.dtb ├── imx7d-var-som-emmc-m4.dtb ├── imx7d-var-som-nand-m4.dtb ├── rootfs.tar.gz ├── rootfs_128kbpeb.ubi ├── rootfs_256kbpeb.ubi ├── SPL-nand ├── SPL-sd ├── u-boot.img-nand ├── u-boot.img-sd └── zImage
The install_yocto.sh script file is located at /usr/bin/