Software upgrade instructions
LQ1808 has a flexible starting method. Under normal circumstances, unless the hardware is damaged, the LQ1808 development board will not be bricked.
If an accident occurs during the upgrade process and the bootloader is damaged, making it impossible to upgrade again, you can still enter the MaskRom mode to repair it.
Loading method
LQ1808 has 32KB BootRom and 2MB internal SRAM, and supports loading the system from the following devices:
SPI interface
eMMC interface
SDMMC interface
In addition, LQ1808 supports downloading system code from the USB OTG interface.
Start sequence
The startup sequence is as follows:
Main control power-on initialization
The BootRom code runs on SRAM to verify the bootloader in the storage device
After the verification is passed, load and run the bootloader boot code
The bootloader boot code is responsible for initializing the DDR memory, loading the complete bootloader code into the DDR memory and running
The bootloader loads the Linux kernel on the storage device and gives the execution rights to the Linux kernel
Start mode
LQ1808 has three startup modes:
Normal mode
Loader mode
MaskRom mode
Normal mode
Normal mode is the normal startup process. Each component is loaded in turn and enters the system normally.
Loader mode
In Loader mode, the bootloader will enter the upgrade state, waiting for host commands for firmware upgrades, etc. To enter the Loader mode, the bootloader must detect that the RECOVERY button is pressed during startup and the USB is connected. The method to make the device enter the upgrade mode is as follows:
Disconnect the power adapter
Connect the double male USB cable to the device and the host, and connect the board end to the USB3.0 OTG port.
Press and hold the RECOVERY button on the device.
Plug in the power source.
After about two seconds, release the RECOVERY button.
MaskRom mode
MaskRom mode is used to repair the system when the bootloader is damaged.
Generally, it is not necessary to enter the MaskRom mode. Only when the bootloader verification fails (the IDB block cannot be read, or the bootloader is damaged), the BootRom code will enter the MaskRom mode. At this time, the BootRom code waits for the host to transmit the bootloader code through the USB interface, load and run it.