DocID026337 Rev 1

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AN4491

Updater BLUE flag

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Updater BLUE flag

There is 4 bytes of data stored in the firmware region as a flag (called BLUE flag). When the

flag is set to a particular known value, it indicates that there is a valid firmware stored in the

Flash. When new firmware programming is started, a special command should first be

called to erase the BLUE flag. The flag should be set only at the end of the programming

phase, if the firmware is correctly updated. So, if the firmware update procedure is not

properly done, the flag is not set and the updater will be forced to stay in the program mode.

This mechanism prevents BlueNRG from running a corrupted firmware that will cause

unexpected malfunctioning.