Ameba-D User Manual
User Manual All information provided in this document is subject to legal disclaimers. © REALTEK 2019. All rights reserved.
456
+1
+1
+1
+1
+1
+1
+1
-1
-1
-1
-1
-1
-1
-1
1
2
3
4
199
198
3
2
1
0
199
198
PHA
PHB
PC
Direction
0
197
197
MPC=199
Fig 21-6 Position count state when CNT_SC = 1
21.2.2.2
Position Counter Reset Mechanism
For applications that absolute position, the position counter need to be reset on the IDX pulse. Fig 21-7 and Fig 21-8 shows the position
counter reset mechanism of the Q-decoder. In the example of Fig 21-7, the movement direction is forward and the position counter is reset on
the index pulse signal with the (PHA, PHB) state is (0, 0). In the example of Fig 21-8, the movement direction is reverse and the position counter
is reset on the index pulse signal with the (PHA, PHB) state is (0, 0). Besides, the maximum position counter is set to 199.
0
1
2
3
PHA
PHB
IDX
7
6
5
4
5
4
3
2
1
0
199
Fig 21-7 Position counter reset on index pulse (forward direction)
198
PHA
PHB
IDX
8
9
1
2
197
196
197
198
199
199
0
0
3
4
Fig 21-8 Position counter reset on index pulse (reverse direction)
Because of processing technology reasons, for some encoder, the index pulse can’t be fully aligned with the edge of state phase changing. If
the width of the IDX pulse is bigger than 1 state, the software can use the register setting to locate the IDX pulse to a specified state and reset
position counter. In the example of Fig 21-9, position counter resets on state (1, 0). In this case, position counter can also configured to be
reset on state (1, 1), (0, 1), but state (0, 0) fails.
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2019-05-15 10:08:03