JN-AN-1003 Boot Loader Operation

All Jennic JN51xx wireless microcontrollers have a ROM boot loader. This boot loader is executed by the CPU following a reset, on waking from sleep or deep sleep mode, and when power is applied. It is designed to operate with external serial memory (normally Flash memory) connected to the SPI interface, loads the user application into RAM and starts program execution.

This Application Note describes the functionality of the boot loader, covering the following topics:

• Operation of the ROM boot loader after a cold start
• Operation of the ROM boot loader after a warm start
• The Flash image application header
• The serial interface used to communicate with the boot loader

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