Method for Operating a Control Unit for a Parking Brake System

A method for operating a control unit for a parking brake system comprising a parking brake, a first microcontroller, a second microcontroller, a first electronic circuit arrangement, a second electronic circuit arrangement, and a first H-bridge and a second H-bridge configured to control a first servomotor and a second servomotor of the parking brake, the method comprising:

• testing the first microcontroller and the second microcontroller one after the other when the control unit is switched on;
• starting nominal operation of the control unit after the test is ended by activating the second microcontroller to control the first servomotor and the second servomotor and deactivating the first microcontroller as a redundancy;
• when an error occurs in the second microcontroller, switching from the nominal operation to a non-nominal operation in which the first microcontroller takes over control of the first servomotor and the second servomotor from the second microcontroller;
• and
• transmitting during the nominal operation, only operationally relevant data from the second microcontroller to the first microcontroller so that the transmitted data are available to the first microcontroller when the error occurs.