TMC4330A Datasheet | Document Revision 1.01 • 2017-JAN-12
33/166
Changing ramp parameters1 and/or operation mode during motion is not advised. However, if
this is necessary, the following applies:
Avoid unintended system behavior during positioning mode!
NOTICE
Ramp parameter value changes during ramp progress can lead to:
A temporary overshooting of XTARGET or mechanical stop positions.
A temporary overshooting of VACTUAL beyond VMAX because the bows B1, B2,
B3, and B4 are maintained during the ramp progress.
This will ensure smooth operation during positioning mode.
1 Exceptions are XTARGET and VMAX. These Parameters can be changed during motion.
However, if it is necessary to change ramp parameters for S-shaped ramps
during motion or to swtich from velocity to positioning mode, do as follows:
Changing Ramp
Parameters
during S-shaped
Motion or
Switching to
Positiong Mode
Action:
Set or set again proper BOW3 registers 0x2F, regardless of wether the value
changes or not.
i
Set this parameter after all other parameters have been set.
Result:
Internal ramp calculations are reset through which the velocity ramp operates at safe
mode. During this mode, the target velocity is set to 0. In case the internal ramp
calculations are up-to-date, the ramp, which is configured by the actual ramp
parameters, is continued.
In order to configure S-shaped ramps with starting and finishing values for
acceleration or deceleration, do as follows:
Configuration of
S-shaped Ramp
with ASTART and
DFINAL
Action:
Set RAMPMODE(1:0)=b’10 (register 0x20).
Set S-Shaped ramp as explained above (BOW1 … BOW4, AMAX, DMAX).
Set proper ASTART register 0x2A.
Set proper DFINAL register 0x2B.
Set proper VMAX register 0x24.
Result:
The internal velocity VACTUAL is changed successively to VMAX with S-Shaped ramps.
v(t)
B1 B12 B2 B23 B3 B34 B4
VMAX
ASTART>0
DFINAL>0
t
Figure 21: S-shaped Ramp with initial and final Acceleration/Deceleration Values
Description is continued on next page.
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