Datasheet

Programming manual L6470
44/70 Doc ID16737 Rev 5
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
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.
9.1.10 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
Tabl e 12 .
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
where INT_SPEED is the integer number stored in the register and tick is 250 ns.
step/s[]
FS_SPD 0.5+()2
18–
⋅
tick
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Table 12. Voltage amplitude regulation registers
KVAL_X [7..0] Output voltage
00000000 0
00000001 V
S
x (1/256)
… … … … … … … … …
11111110 V
S
x (254/256)
11111111 V
S
x (255/256)
step s⁄[]
INT SPEED– 2
26–
⋅
tick
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