Microcontroller and method for initializing a microcontroller

A method for initializing a microcontroller, comprising:

• generating an internal clock signal in a microcontroller-internal timing hardware circuit;
• based on the internal clock signal, determining a frequency of an external clock signal provided to the microcontroller;
• determining whether the frequency of the external clock signal falls within a permissible frequency range;
• wherein, when the frequency is determined to be within the permissible frequency range, determining at least one parameter and using the at least one parameter in a clock changing hardware circuit to change the external clock signal into a useful clock signal with a predefined frequency;
• and
• wherein, when the frequency is determined to be outside of the permissible frequency range, interrupting a start-up process of the microcontroller in a first mode and triggering a further startup of the microcontroller in a second mode that differs from the first mode;
• wherein the second mode is a mode in which the internal clock signal is used as a timer, or is a locked mode which prevents changes and prevents a further start-up and which can only be overcome by replacing an external timing device configured to provide the external clock signal;
• or is a mode that outputs a warning.

A microcontroller, comprising:

• a terminal contact configured to receive an external clock signal having a first stability and/or a first precision;
• an internal timing hardware circuit having an output and configured to generate an internal clock signal having a second stability and/or a second precision, the second stability and/or the second precision being less than the first stability and/or the first precision, respectively;
• a timer hardware circuit having a first input, a second input, and an output, the first input of the timer hardware circuit electrically connected to the terminal contact, the second input of the timer hardware circuit independent of the first input of the timer hardware circuit and electrically connected to the output of the internal timing hardware circuit;
• and
• a clock changing hardware circuit having a first input, a second input, and an output, the first input of the clock changing hardware circuit coupled to the terminal contact, the second input of the clock changing hardware circuit coupled to the output of the timer hardware circuit.