1. MaskRom 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 need enter MaskRom Upgrade Mode.

❶ Power off the development board. Connect the PC to the board using a USB Type-A cable.

❷ Short the BOOT_SARADC_VIN0 pin to GND.

Caution

Short only the two pins. Avoid touching other parts to prevent short circuits and board damage.

❸ Power on the board. It will then boot into Maskrom mode.