Fuse bit

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When Fuse bits are bits of microcontrollers referred to the configuration used the microcontroller and can not be changed by the software. These can, for example, be security settings that prevent data from being read from the microcontroller. Further settings are used, for example, to determine the internal clock rate or to activate a bootloader . Fuse comes from English and means, when translated, fuse . In the past, fuse bits were contacts that could be melted. Certain functions could be switched on or off through the contacts. Nowadays this is mostly only used for security-relevant functions, for example read / write protection, since the process is irreversible. Less critical functions are mapped in a write-protected register in a flash memory . The write protection can be canceled by writing the defined key in the corresponding register so that the set fuses can be reconfigured.