Method for Trimming an Adjustable Oscillator to Match a CAN-Bus and a CAN-Bus Communication Controller

A method for trimming a cycle time of an adjustable oscillator to match a Controller Area Network-bus (CAN-bus) operating with a predetermined bit time, comprising:

• detecting a first falling edge of a bit transmitted on the bus within a CAN-bus message;
• waiting for a predetermined number of cycles of the adjustable oscillator;
• detecting a second falling edge of a bit transmitted on the bus;
• and
• determining a measured number of cycles of the adjustable oscillator between the detection of the first falling edge and the second falling edge;
• determining a deviation between the measured number of cycles and an integer multiple of a nominal number of cycles per bit time;
• and
• adjusting the cycle time of the adjustable oscillator when the deviation is greater than a predetermined tolerance value.

A Controller Area Network-bus (CAN-bus) communication controller for a CAN-bus operating with a predetermined bit time, comprising:

• an access unit comprising one or more terminals for signal lines of the CAN-bus, the access unit being adapted to detect a first signal and a second signal within a CAN-bus message transmitted on the CAN-bus;
• an adjustable oscillator having an output coupled with the access unit to provide an operating clock signal for the access unit;
• and
• a controller module coupled to the adjustable oscillator and adapted to determine an information about a present cycle time of the local oscillator using a measured number of cycles of the adjustable oscillator between the first signal and the second signal and a nominal number of cycles per bit time.

A node for a Controller Area Network-bus (CAN-bus) operating with a predetermined bit time, comprising:

• a CAN-bus communication controller comprising one or more terminals for signal lines of the CAN-bus;
• an adjustable oscillator having an output coupled with the communication controller to provide an operating clock signal for the communication controller;
• and
• a controller module coupled to a control input of the adjustable oscillator and to a control input of the CAN-bus communication controller, wherein the controller module is adapted to:
• operate the communication controller such that the communication controller monitors the signal lines of the CAN-bus to indicate the detection of a first and a second signal within a CAN-bus message transmitted on the bus to the controller module;
• and
• determine an information about a present cycle time of the adjustable oscillator using a measured number of cycles of the adjustable oscillator between the detection of the first signal and the second signal and a nominal number of cycles per bit time.

A computer program having a program code on a non-transitory medium for performing, when the computer program is executed on a computer or processor, a method for trimming a cycle time of an adjustable oscillator to match a Controller Area Network-bus (CAN-bus) operating with a predetermined bit time, comprising:

• operating a communication controller such that the communication controller monitors the signal lines of the CAN-bus to indicate the detection of a first signal and a second signal within a CAN-bus message transmitted on the bus to the controller module;
• determining an information about a present cycle time of the adjustable oscillator using a measured number of cycles of the adjustable oscillator between the detection of the first signal and the second signal and a nominal number of cycles per bit time;
• and
• trimming the cycle time of an adjustable oscillator to match the predetermined bit time based on the determined information.