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6 Encoder
A
B
G r a y C o u n t e r
H i g h R e s o l u t i o n C o u n t e r
0 1 2 3 0 1 2 3 2 1 0 3 2 1 2 3 0
0 1 2 3 4 5 6 7 6 5 4 3 2 1 2 3 4
1
5
F o u r P h a s e C o u n t e r
0 1 0 1
Figure 6.2: Encoder Modes
6.2 Encoder trigger output
The trigger output of the encoder reacts to changes of the position counter. Triggers are
generated according to the EncoderOutputMode property:
Off Disables the encoder output trigger.
PositionUp
Triggers are generated whenever the position counter increments and the position
value has not previously been reached.
PositionDown Triggers are generated whenever the position counter decrements and the
position value has not previously been reached.
DirectionUp Triggers are generated whenever the position counter increments.
DirectionDown Triggers are generated whenever the position counter decrements.
Motion
Triggers are generated whenever the position counter value changes.
In order to keep track of the highest respectively lowest position in the PostionUp and -Down
modes, a watermark counter is used. The counter resets whenever the output mode changes,
the encoder is reset or a new start value is written. See Fig. 6.3 for a comparison of the modes.
The number of generated output triggers can be reduced by setting the EncoderDivider
H i g h R e s o l u t i o n M o d e
A
B
G r a y C o u n t e r
E n c o d e r C o u n t e r
P o s i t i o n U p T r i g g e r
P o s i t i o n U p W a t e r m a r k
0 1
0 1
2
0 1
3 0 1 2 3 0 1
2
2
3
3
4
4
5
5
0 3 2 1 0 1 2 3 0 1 2 3 0 1
6
6
7
7
8
8
9
9
8 7 6 5 4 5
2
6 7 8 9 1 0 1 1 1 2 1 3 1 4
1 0 1 1 1 2 1 3 1 4
P o s i t i o n D o w n T r i g g e r
D i r e c t i o n U p T r i g g e r
D i r e c t i o n D o w n T r i g g e r
M o t i o n T r i g g e r
P o s i t i o n D o w n W a t e r m a r k
0
Figure 6.3: Encoder Output Modes
property accordingly. This property only affects the trigger output, the position is tracked
exactly the same independent of the divider value.
6.3 Encoder Status
The encoder has different states which reflect on the A/B input signals. The current state can
be read out by the EncoderStatus register. The following list shows the available states:
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