Method for determining the duty factor of a pulse-width-modulated signal by means of a vehicle control unit, and vehicle control unit

Abstract

For safety reasons, a redundant measurement of the duty factor of pulse-with-modulated signals 12 is performed in a vehicle control unit, such as in particular a brake control unit 10. Here, in the prior art, the duty factor of the pulse-width-modulated signal 12 is determined by way of a low-pass filter and an analogue-digital conversion and is compared with a value determined by way of a memory and comparison unit. According to the invention, a direct determination of the duty factor of the signal 12 is performed by way of periodic sampling. For this purpose, the durations of the states 18 and 20 of the signal 12 are determined with the aid of a clock signal 32. After one complete cycle, the duty factor can then be determined directly from the ratio of the durations of the states 18 and 20.

Description

technical field [0001] The invention relates to a method for determining the duty cycle of a pulse width modulated signal by means of a vehicle controller according to the preamble of claim 1 . The invention also relates to a vehicle controller according to claim 18 . Background technique [0002] The vehicle controller serves to control or monitor individual or multiple functions of a vehicle, in particular a motor vehicle. In this case, usually either external signals or measured values ​​are processed, which correspondingly have to be received or detected by the controller. The measured value reception or signal detection and also the signal processing itself must generally also meet high safety requirements in order to prevent malfunctions to the greatest extent possible. Depending on the use and function of the vehicle controller, the requirements may vary. [0003] In this case, the brake controller is a vehicle controller which usually has to meet particularly high...

AI Technical Summary

Problems solved by technology

[0007] The known method for redundant acquisition of duty cycles has the disadvantage that, in addition to the microcontroller, external components are required for this, namely at least one low-pass filter and one or more A / D converters

This takes up space on the board, causes additional cost and has to be built

Additionally, undesired delays occur due to analog-to-digital conversion or low-pass filtering

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