AMIS-30622 Datasheet, PDF (12/42 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30622
Notes
(1) The Vmax factor is an approximation
(2) In case of motion without acceleration (AccShape = 1) the length of the steps = 1/Vmin. In case of accelerated
motion (AccShape = 0) the length of the first step is shorter than 1/Vmin depending of Vmin, Vmax and Acc.
8.4. Acceleration and deceleration
Sixteen possible values can be programmed for Acc (acceleration and deceleration between Vmin and Vmax).
The table below 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.
Vmax (FS/s) →
Acc index ↓
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
99 136 167 197 213 228 243 273 303 334 364 395 456 546 729 973
Acceleration (Full-step/s²)
49
106
473
218
735
1004
3609
6228
8848
11409
13970
16531
19092
21886
24447
27008
29570
29570
34925
40047
The formula to compute the number of equivalent Full-step during acceleration phase is:
Nstep
=
Vmax ² − Vmin²
2 × Acc
8.5. Positioning
The position programmed in command SetPosition is given as a number of (micro)steps. According to the
chosen stepping mode, the position words must be aligned as described in the table below. When using
command GotoSecurePosition, data is automatically aligned.
Stepping mode
Position word: Pos[15:0]
Shift
1/16^th
S B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 LSB No shift
1/8^th
S B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 LSB 0 1-bit left ⇔ ×2
1/4^th
S B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 LSB 0 0 2-bit left ⇔ ×4
Half-stepping S B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 LSB 0 0 0 3-bit left ⇔ ×8
SecurePosition S B9 B8 B7 B6 B5 B4 B3 B2 B1 LSB 0 0 0 0 0
No shift
8.5.1. Position ranges
A position is coded by using the binary two’s complement format. According to the positioning commands which
are used (see § 9.2.2.10 Application Commands) and to the chosen stepping mode, the position range will be as
shown in the table below.
Command
SetPosition
Stepping mode
Half-stepping
1/4^th micro-stepping
1/8^th micro-stepping
1/16^th micro-stepping
Position range
-4096 to +4095
-8192 to +8191
-16384 to +16383
-32768 to +32767
Full range
excursion
8192 half-steps
16384 micro-steps
32768 micro-steps
65536 micro-steps
Number
of bits
13
14
15
16
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