VAR-SOM-AM33 Yocto NAND Recovery

From Variscite Wiki

1 NAND Recovery introduction

As an easy and fast way to recover the VAR-SOM-AM33 NAND flash, Variscite provides a recovery SD card image that can be used to install the pre-built Linux and Android systems.
This SD card image includes a script ( that installs all the boot images and root file-system.

2 Download Variscite's pre-built recovery SD card image

Download am33-som-nand_recovery-sd-....img.gz from Variscite's FTP server:

2.1 Write the image to an SD card

During the SD card image writing all files and partitions are erased from target device.
Double check that the device is correct to avoid accidentally overwriting a different device and potentially damaging your existing operating system.

2.1.1 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)

2.1.2 Using a Windows based host

  • Download Win32 Disk Imager from: 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. 

2.1.3 Using a Mac OS X host

Use the dd Utility for MAC OS X to flash .img files to your SD card

3 Connect target debug serial to linux host

Follow :
to connect target serial debug port to host PC

4 Boot NAND recovery SD-Card

  • Power-off the board.
  • Insert the SD card into the SD/MMC slot of the carrier board (DVK)
  • Press and hold the boot-select button, and power-on the board while button is pressed
  • The board will automatically boot into Linux from SD-Card
  • login as 'root', no password is required

5 NAND recovery script usage

NAND recovery script usage:

usage: /sbin/ options

This script install Linux/Android binaries in VAR-SOM-AM33 NAND.

  -h Show this message
  -o <Linux|Android> OS type (default: Linux).