AMIS-30621 LIN Micro-stepping Motor Driver
Data Sheet
12.4 Acceleration and Deceleration
Sixteen possible values can be programmed for Acc (acceleration and deceleration between Vmin and Vmax). Table 9 provides the
obtainable values in full-step/s². One observes restrictions for some combination of acceleration index and maximum speed (gray cells).
The accuracy of Acc is derived from the internal oscillator.
Table 9: Acceleration and Deceleration Selection Table
99
136 167 197 213 228 243 273 303 334 364 395 456 546 729 973
Vmax (FS/s) →
↓ Acc index
Acceleration (Full-step/s²)
Hex
0
1
Dec
0
49
106
473
735
1
218
2
2
1004
3
3
3609
4
4
6228
5
5
8848
6
7
8
9
A
B
C
D
E
F
6
7
8
9
10
11
12
13
14
15
11409
13970
16531
19092
21886
24447
27008
29570
34925
40047
29570
The formula to compute the number of equivalent full-step during acceleration phase is:
Vmax 2 − Vmin2
Nstep =
2× Acc
12.5 Positioning
The position programmed in commands SetPositionand SetPositionShortis given as a number of (micro) steps. According to
the chosen stepping mode, the position words must be aligned as described in Table 10. When using command SetPositionShort
or GotoSecurePosition, data is automatically aligned.
Table 10: Position Word Alignment
Stepping mode
Position word: Pos[15:0]
Shift
No shift
1-bit left ⇔ ×2
2-bit left ⇔ ×4
3-bit left ⇔ ×8
No shift
1/16th
S
S
S
S
S
S
B14 B13 B12 B11 B10 B9
B8
B7
B6
B5
B5
B3
B7
B6
B5
B4
B4
B2
B6
B5
B4
B3
B3
B5
B4
B3
B2
B2
B4
B3
B2
B1 LSB
B1 LSB
B3
B2
B1 LSB
B2
B1 LSB
B1 LSB
1/8th
B13 B12 B11 B10 B9
B8
B7
B6
B6
B4
0
0
0
0
0
1/4th
B12 B11 B10 B9
B8
B7
B7
B5
0
0
0
0
Half-stepping
PositionShort
SecurePosition
B11 B10 B9
B8
B8
B6
0
0
0
S
S
B9
B7
B9
B8
B1 LSB
0
0
No shift
Notes:
(1) LSB: Least Significant Bit
(2) S: Sign bit
AMI Semiconductor – Sept. 2007, Rev 1.5
12
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