Datasheet

TMC4361A Datasheet | Document Revision 1.22 • 2017-JAN-12
92/230
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Read entire documentation; especially the “Supplemental Directives” on page 224.
 MAIN MANUAL 
Current Waves Start Values
As both waves are shifted by 90° for two-phase stepper motors, the sine wave starts
at 0° when MSCNT = 0. By comparison, the cosine wave begins at 90° when
MSCNT = 256. At this starting points the current values are CURRENTA = 0 for the
sine wave and CURRENTB = 247 for the cosine wave.
In contrast to the starting microstep positions that are fixed, these starting current
values can be redefined if the default start values do not fit for the actual MSLUT.
In order to change the starting current values of the MSLUT, do as follows:
Action:
 Define the start values START_SIN and START_SIN90_120 according to the
requirements.
 Set register 0x7E (7:0) = START_SIN
 Set register 0x7E (23:16) = START_SIN90_120
Result:
The starting values for both waves are adapted to MSLUT.
Default MSLUT
The default sine wave table in TMC drivers uses one segment with a base inclination
of 2 and one segment with a base inclination of 1 (see default value of the MSLUTSEL
register 0x78 = 0xFFFF8056).
The segment border X1 is located at MSCNT = 128. The base wave inclinations are
W0 = b’10 (=2) and W1 = b’01 (=1).
As a result, between MSCNT = 0 and 128, the increment value INC is either
1 (if ofs = 0) or 2 (if ofs = 1).
And between MSCNT = 128 and 255, the increment value INC is either
0 (if ofs = 0) or 1 (if ofs = 1).
This reflects the stronger rise in the first segment of the MSLUT in contrast to the
second segment. The maximum value is
START_SIN90_120 = 247.
Starting Current
Values of MSLUT
Configuration
Base Wave
Inclinations