If the firmware is larger than 4G SD upgrade card making tutorial:

Because the "SD_Firmware_Tool" upgrade tool provided by RK, the
upgrade partition made is in FAT32 format, so the supported firmware
size is up to 4G. Now the FAT32 format partition should be reformatted
to EXT4 format. (Note: The previous work is the same as the normal SD
upgrade card, but in the end, you need to reformat the partition and
put in the files required for the upgrade)

Ready to work

Core-3399-JD4

computer

MicroSD card (ie TF card)

Double male USB data cable

USB card reader

Go to

SD Firmware Tool Download Page

 to download "SD_Firmware_Tool" and unzip it.

Run SD_Firmware_Tool.exe


Download the SD card maker tool: SD_Firmware_Tool

You can modify the config.ini file, set Selected=1 to set the language
to Chinese, set Selected=2 to set the language to English.

Download the unified firmware that needs to be upgraded to the
motherboard.

Insert the MicroSD into the USB card reader and then into the USB port
of the computer.

Open SD_Firmware_Tool, check the "Firmware Upgrade" box, select the
correct removable disk device and upgrade the firmware.

After clicking Start Creation, wait for the creation to finish.

Take out the MicroSD card, insert it into the MicroSD card slot of the
motherboard, power on the motherboard, and the motherboard will
automatically start to upgrade.

After the upgrade is complete, take out the MicroSD card and the
motherboard will automatically restart to complete the entire firmware
update process.

Prepare the required files

Because formatting will lose files, now you need to re-prepare the
files required for MicroSD card upgrade

rksdfw.tag

sd_boot_config.config

sdupdate.img

   mkdir my_tmp/
   cd my_tmp/

   #make empty rksdfw.tag
   touch rksdfw.tag

   #Make an upgraded configuration file sd_boot_config.config
   echo "#rockchip sdcard boot config file for factory\
   loader_update = 0\
   display_led = 1\
   display_lcd = 1\
   pcba_test = 0\
   fw_update = 1\
   demo_copy = 0" > sd_boot_config.config

   # Make firmware to be upgraded sdupdate.img
   # Take firmware FIREFLY-RK3399-UBUNTU-18.04_DESKTOP-GPT.img as an example
   cp ~/Downloads/FIREFLY-RK3399-UBUNTU-18.04_DESKTOP-GPT.img sdupdate.img

   # Check for the existence of the following files
   ls rksdfw.tag  sd_boot_config.config  sdupdate.img

Prepare the formatting script "flash.sh" provided by Firefly

   #!/bin/bash

   DISK=$1
   MNT=$2

   sudo umount $DISK
   sudo mkfs.ext4 -F $DISK
   sudo mount $DISK $MNT
   sudo cp rksdfw.tag  sd_boot_config.config  sdupdate.img $MNT
   sudo umount $MNT

Upgrade partition production

Notes (must see):

[sdc]1 <font color = "red">Please be sure to confirm which device node
(sdb or sdc or other) the SD card entered is</font>, so as not to
damage the local system or cause greater production losses.

If it is confirmed that the drive letter is sdc, then the operating
device should be /dev/sdc1 rather than others.

   # Check that the following files exist
   ls rksdfw.tag  sd_boot_config.config  sdupdate.img

   # Give flash.sh execute permission
   chmod +x flash.sh

   sudo ./flash.sh /dev/[sdc]1 /mnt/