Introduction to updating firmware Preface ROC-RK3566-PC has 2 working modes. Under normal circumstances, boot directly into "Normal mode" to start the system normally. If you need to upgrade the board subsystem, you can choose the appropriate "Upgrade mode" to upgrade the firmware according to the situation. Note: The small memory version of ROC-RK3566-PC is installed with the Ubuntu operating system by default, large memory version is installed with Android by default. If users want to run other operating systems, they need to use the corresponding firmware to program to the mainboard.You can go to the Firmware download page to download more firmware. ROC-RK3566-PC is classified according to the working mode and can be divided into two working modes: Normal mode Upgrade mode Among the upgrade modes, the comparison between different upgrade modes: MaskRom Upgrade Mode In general, there is no need to enter "MaskRom Upgrade Mode". Only when the bootloader verification fails (the IDB block cannot be read, or the bootloader is damaged), the BootRom code will enter this mode. At this time, the BootRom code waits for the host to transmit the bootloader code through the USB interface, load and run it. When the board becomes bricked and cannot start or upgrade the program normally, you can also manually enter the "MaskRom Upgrade Mode". To forcibly enter MaskRom Upgrade Mode, please refer to the chapter "MaskRom Upgrade Mode". Loader upgrade mode In "Loader upgrade mode", the bootloader will enter an upgrade state, waiting for host commands for firmware upgrades, etc. To enter this mode, the bootloader must detect a "RECOVERY" key press at startup and the USB is connected. To force into Loader upgrade mode, see the chapter "Loader upgrade mode". SD upgrade mode Using SD upgrade is essentially to make a bootable SD-boot upgrade firmware, let the board SD boot, erase and program the EMMC. To forcibly enter SD upgrade mode, please refer to the chapter "Upgrade Firmware Using SD Card".