Programming manual
Equation 8
powerSTEP01
MIN_SPEED ⋅ 2–24
[step/s]= --------------------------------------------------
tick
where MIN_SPEED is the integer number stored in the register and tick is the ramp 250 ns.
The available range is from 0 to 976.3 step/s with a resolution of 0.238 step/s.
When the LSPD_OPT bit is set high, low speed optimization feature is enabled and the
MIN_SPEED value indicates the speed threshold below which the compensation works. In
this case the minimum speed of the speed profile is set to zero.
Any attempt to write the register when the motor is running causes the NOTPERF_CMD flag
to rise.
11.1.9
FS_SPD
The FS_SPD register contains the following parameters:
Table 14. FS_SPD register
Bit 11
Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
BOOST_MODE
FS_SPD
The FS_SPD threshold speed value over which the step mode is automatically switched to
full-step two-phase on. Its value is expressed in step/tick (format unsigned fixed point 0.18)
and to convert it in step/s the following formula can be used:
Equation 9
(FS_SPD + 0.5) ⋅ 2–18
[step/s]= ----------------------------------------------------------
tick
If FS_SPD value is set to hFF (max.) the system always works in Microstepping mode
(SPEED must go over the threshold to switch to Full-step mode). Setting FS_SPD to zero
does not have the same effect as setting the step mode to full-step two-phase on: the zero
FS_SPD value is equivalent to a speed threshold of about 7.63 step/s.
The available range is from 7.63 to 15625 step/s with a resolution of 15.25 step/s.
The BOOST_MODE bit sets the amplitude of the voltage squarewave during the full-step
operation (see Section 7.4.1).
11.1.10 KVAL_HOLD, KVAL_RUN, KVAL_ACC and KVAL_DEC
These registers are specific for voltage mode driving (see Section 8).
The KVAL_HOLD register contains the KVAL value that is assigned to the PWM modulators
when the motor is stopped (compensations excluded).
The KVAL_RUN register contains the KVAL value that is assigned to the PWM modulators
when the motor is running at constant speed (compensations excluded).
The KVAL_ACC register contains the starting KVAL value that can be assigned to the PWM
modulators during acceleration (compensations excluded).
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