TMC428_06 Datasheet, PDF (41/58 Pages) List of Unclassifed Manufacturers – Intelligent Triple Stepper Motor Controller with Serial Peripheral Interfaces

TMC428 DATASHEET (v. 2.02 / April 26^th, 2006)
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These 32 datagrams (Table 12-2) are sufficient for all programmable micro step resolutions. If micro
stepping is used for at least one stepper motor, these 32 datagrams have to be sent once to the
TMC428 for initialization of the micro step table after power-on reset. The initialization of the micro step
look-up-table is not necessary, if full stepping is used for all stepper motors. The on-chip RAM is not
initialized during power-on reset. So, the full initialization of the whole micro step look-up-table is
recommended to avoid trouble caused by missing look-up table entries. Additionally, a fully initialized
micro step look-up-table allows the selection of individual micro step resolutions for different steppes.
12.1 Stepping through the Wave Look-Up-Table
The 64 values of the wave look-up table (LUT) hold a quarter period of a sine wave, indexed from 0 to
63. This quarter sine wave is expanded to full sine wave and full cosine wave by indexing the 64 values
of the LUT. The LUT index is mapped from a wave index of a full period from 0 to 255. The stepping
through the LUT is done with fixed increment width. The increment width is a power of two and it
depends on the micro step resolution selection usrs. The Table 12-4 gives the indices for the LUT for
the different micro step resolutions. For motion in positive direction, the full period index is incremented
from micro step to micro step. For motion into negative direction, the full period index is decremented
from micro step to micro step.
The sine is associated to phase A (PH_A) and the cosine is associated to phase B (PH_B). The phase
bits represent the sign of the sine resp. cosine function. The polarity of the phase bit (PH_A, PH_B)
and the polarity of the fast decay control bits (FD_A, FD_B) can be changed by the polarity bits within
the global stepper motor parameter register (see section 9.7, page 29).
MSBs of full
wave index (range)
%00 (0...63)
%01 (64...127)
%10 (128...191)
%11 (192...255)
Quadrant
1^st
2^nd
3^rd
4^th
PH_A (sin)
1
1
0
0
PH_B (cos)
1
0
0
1
Table 12-3: Phase Bits and Fast Decay Control Bits
FD_A (sin)
0
1
0
1
FD_B (cos)
1
0
1
0
Copyright © 2004-2006, TRINAMIC Motion Control GmbH & Co. KG