TMC262 DATASHEET (Rev. 2.07 / 2013-FEB-14)
14
increases the current. When the load decreases and SG rises above (SEMIN + SEMAX + 1) x 32 the
current becomes reduced.
motor current reduction area
current setting CS
(upper limit)
SEMAX+SEMIN+1
SEMIN
½ or ¼ CS
motor current increment area
stall possible
(lower limit)
0=maximum load
time
load
angle
load angle optimized
load angle optimized
optimized
Figure 5.2 coolStep adapts motor current to the load
Four more parameters control coolStep and one status value is returned:
Parameter
Description
Range
Comment
Current scale. Scales both coil current values as
taken from the internal sine wave table or from
the SPI interface. For high precision motor
operation, work with a current scaling factor in
the range 16 to 31, because scaling down the
current values reduces the effective microstep
resolution by making microsteps coarser. This
setting also controls the maximum current value
set by coolStep™.
CS
0… 31
scaling factor:
1/32, 2/32, … 32/32
SEUP
SEDN
Number of increments of the coil current for each 0… 3
occurrence of an SG measurement below the
lower threshold.
Number of occurrences of SG measurements 0… 3
above the upper threshold before the coil current
is decremented.
step width is:
1, 2, 4, 8
number of stallGuard
measurements per
decrement:
32, 8, 2, 1
SEIMIN
Mode bit that controls the lower limit for scaling
the coil current. If the bit is set, the limit is ¼ 0
CS. If the bit is clear, the limit is ½ CS.
1
Minimum motor
current:
1/2 of CS
1/4 of CS
Status word
Description
Range
Comment
SE
5-bit unsigned integer reporting the actual 0… 31
current scaling value determined by coolStep.
This value is biased by 1 and divided by 32, so
the range is 1/32 to 32/32. The value will not be
greater than the value of CS or lower than either
¼ CS or ½ CS depending on the setting of
SEIMIN.
Actual motor current
scaling factor set by
coolStep:
1/32, 2/32, … 32/32
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