TMC4330A Datasheet | Document Revision 1.01 • 2017-JAN-12
36/166
S-shaped Ramps
with initial Start
Velocity
In order to use S-shaped ramps with initial start velocity, do as follows:
Action:
Set RAMPMODE(1:0)=b’10 (register 0x20).
Set S-shaped ramp type accordingly, as explained before.
Set proper VSTART > 0 (register 0x25).
Set VSTOP = 0 (register 0x26).
Result:
The S-shaped ramp starts with initial velocity.
PRINCIPLE:
The initial acceleration value is equal to AMAX. The parameter ASTART is not
considered. Consequently, ramp phase B1 is not performed.
v(t)
B1 B12 B2 B23 B3 B34 B4
VMAX
VSTART
t
Figure 23: S-shaped Ramp with initial Start Velocity
If S-shaped ramp with initial velocity VSTART is selected:
Avoid unintended system behavior during positioning mode!
NOTICE
Keep in mind that the S-shaped character of the curve is maintained. Because
AMAX is the start acceleration value, the ramp will always execute phase B2
which could result in positioning overshoots.
Use VSTART only in positioning mode if there is enough distance between the
current position XACTUAL and the target position XTARGET.
This will ensure smooth operation during positioning mode.
Turn page for information on how to configure finishing ramps with stop velocity.
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