XC161 Datasheet, PDF (27/419 Pages) Infineon Technologies AG – 16-Bit Single-Chip Microcontroller with C166SV2 Core Volume 2 (of 2): Peripheral Units

XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
The General Purpose Timer Units
As in incremental interface mode two input signals with a 90° phase shift are evaluated,
their maximum input frequency can be half the maximum count frequency.
In incremental interface mode, the count direction is automatically derived from the
sequence in which the input signals change, which corresponds to the rotation direction
of the connected sensor. Table 14-4 summarizes the possible combinations.
Table 14-4 GPT1 Core Timer T3 (Incremental Interface Mode) Count Direction
Level on Respective
T3IN Input
other Input
Rising
Falling
T3EUD Input
Rising
Falling
High
Down
Up
Up
Down
Low
Up
Down
Down
Up
Figure 14-9 and Figure 14-10 give examples of T3’s operation, visualizing count signal
generation and direction control. They also show how input jitter is compensated, which
might occur if the sensor rests near to one of its switching points.
T3IN
T3EUD
Forward Jitter Backward Jitter
Forward
Contents
of T3
Up
Down
Up
Note: This example shows the timer behaviour assuming that T3 counts upon any
transition on input, i.e. T3I = '011 _B'.
MCT04373
Figure 14-9 Evaluation of Incremental Encoder Signals, 2 Count Inputs
User’s Manual
GPT_X1, V2.0
14-13
V2.2, 2004-01