What is a
Bootable SD-Cardis an SD-Card that has a bootloader installed on it.
Bootable SD-Cardis also known as a
Boot-Disk, and your target device will be able to boot from the SD-Card, as though it were the onboard eMMC storage.
Why do we need a
Bootable SD-Cardcan be used to speed up the development process.
- If you want to release ROM for an SD-Card, the
Bootable SD-Cardcan be used during your development process.
- In some extreme cases, when your target-device is unable to boot from the eMMC (e.g. damaged bootloader), you can use a
Bootable SD-Cardto do your system/file recovery.
The operation of VIM1, VIM2 and VIM3 is almost the same, so this document will take VIM1 as an example.
Download U-Boot (VIM1/VIM2/VIM3) or build U-Boot to get the bootloader blob for your SD-Card.
No matter which method you choose, you need to keep in mind that there are different bootloader blobs for different boot disks/media:
- U-Boot blob
u-boot.bin.sd.binis built for SD-Cards
- U-Boot blob
u-boot.binis built for eMMC Storage
Insert the SD-Card into your PC, and make sure the disk is unmounted:
$ sudo umount /dev/sdX1
Format the SD-Card as Fat32:
$ sudo mkfs.vfat /dev/sdX1
dd to write the U-Boot blob into the first sector of SD-Card:
$ sudo dd if=u-boot.bin.sd.bin of=/dev/sdX conv=fsync,notrunc bs=1 count=444
Eject the SD-Card from your PC:
$ sudo eject /dev/sdX
sdXwith the correct one on your PC.
Open a terminal and type the
sudo minicom command or other serial tool you like.
Insert the Bootable SD-Card you created previously, into your target device and power-on. The terminal should print this out which means the board is booted from SD card: