Infineon Technologies XC161, User Manual

Page: 27 / 419

XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
The General Purpose Timer Units
User’s Manual 14-13 V2.2, 2004-01
GPT_X1, V2.0
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.
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.
Figure 14-9 Evaluation of Incremental Encoder Signals, 2 Count Inputs
Table 14-4 GPT1 Core Timer T3 (Incremental Interface Mode) Count Direction
Level on Respective
other Input T3IN Input T3EUD Input
Rising Falling Rising Falling
High Down Up Up Down
Low Up Down Down Up
MCT04373
Forward Jitter Backward Jitter Forward
T3IN
T3EUD
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
'.