Data Sheet

16

1.10

2018-09-13

TLE4929C Crankshaft Sensor

Fully Programmable Crankshaft Sensor

Figure 7

Direction Detection Principle: Rotation Direction Forward And Backward

3.3.7

Direction Detection Threshold

To recognize a change in rotational direction of the target wheel a threshold (Figure 8) is used. The peak-to-

peak signal of direction is averaged over the last 5 teeth and is used as 100% value. Whenever a new minimum

or a new maximum is measured, a threshold of 25% is calculated.

Figure 8

Direction Threshold Level

At a constant direction the next sample-point is expected to have another 100% signal amplitude. In the case

of a rotational direction change the same value as before is expected. To distinguish between these two cases

a virtual threshold of 25% is taken into account. Using EEPROM these 25% can be programmed to 12.5%

(direction change criterion).

Speed

direction

falling edge,

dir samples used for

direction detection

rising edge,

dir samples used for

direction detection

Speed

direction

amplitude

falling edge,

dir samples used for

direction detection

rising edge,

dir samples used for

direction detection

Rotation direction Forward

Rotation direction Backward

Speed

direction

falling edge

,

dir samples used for

direction detection

Rotation direction Left

Rotation direction Right

25%

100%

<25%

Direction change

>25%

Same direction