8 Device Firmware Update (DFU)

The Device Firmware Update of the RNWF11 is performed with the bootloader stored in the RNWF11’s boot Flash memory. DFU utility script is executed on PC to upgrade the RNWF11’s firmware over UART. When DFU is being performed, the bootloader communicates with the DFU utility over UART interface. DFU utility transfers the firmware image to the bootloader on the RNWF11and the bootloader programs the firmware image to the RNWF11 program Flash.

Bootloader and Application Flow

When the RNWF11 boots up, it starts executing the bootloader first and waits for three seconds to receive boot command from the host MCU. The boot command is used to configure the program to boot to application mode or continue running in bootloader for DFU. If the program does not receive the boot command, it will boot to the application after timeout. The program reads the application Flash to check the CRC value of the application before jumping to the application. The program continues to run the bootloader if the CRC verification is failed.

Figure 8-1. Bootloader and Application Flow