EVAL6470H Datasheet, PDF (44/70 Pages) STMicroelectronics – dSPIN fully integrated microstepping motor driver with motion engine and SPI

Programming manual
L6470
9.1.10
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
[step/s] = ⁽---^F----^S----^_----^S----^P----^D------+----⁰----^.-⁵----⁾----^â‹-----²----^–---¹--⁸-
tick
If the FS_SPD value is set to h3FF (max.) the system always works in microstepping mode
(SPEED must go beyond the threshold to switch to Full-step mode). Setting FS_SPD to zero
does not have the same effect as setting 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.
KVAL_HOLD, KVAL_RUN, KVAL_ACC and KVAL_DEC
The KVAL_HOLD register contains the K_VAL value that is assigned to the PWM modulators
when the motor is stopped (compensation excluded).
The KVAL_RUN register contains the K_VAL value that is assigned to the PWM modulators
when the motor is running at constant speed (compensation excluded).
The KVAL_ACC register contains the starting K_VAL value that can be assigned to the PWM
modulators during acceleration (compensation excluded).
The KVAL_DEC register contains the starting K_VAL value that can be assigned to the PWM
modulators during deceleration (compensation excluded).
The available range is from 0 to 0.996 x V_S with a resolution of 0.004 x V_S, as shown in
Table 12.
Table 12. Voltage amplitude regulation registers
KVAL_X [7..0]
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
Output voltage
0
V_S x (1/256)
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
V_S x (254/256)
V_S x (255/256)
9.1.11
INT_SPEED
The INT_SPEED register contains the speed value at which the BEMF compensation curve
changes slope (see Section 7.4). Its value is expressed in step/tick and to convert it in
step/s, the following formula can be used:
Equation 10
[step ⁄ s] = -^I--^N----^T----–----^S----^P----^E-----^E----^D------^â‹-----²----^–---²--⁶-
tick
where INT_SPEED is the integer number stored in the register and tick is 250 ns.
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