EVAL6470H Datasheet, PDF (23/70 Pages) STMicroelectronics – dSPIN fully integrated microstepping motor driver with motion engine and SPI

L6470
6.4.1
Functional description
Automatic full-step mode
When motor speed is greater than a programmable full-step speed threshold, the L6470
switches automatically to Full-step mode (see Figure 7); the driving mode returns to
microstepping when motor speed decreases below the full-step speed threshold. The full-
step speed threshold is set through the FS_SPD register (see Section 9.1.9).
Figure 7. Automatic full-step switching
I
peak
Phase A
sin(π/4) x I_peak
Phase B
μStepping
(2N+1) x π/4
Full-Step
(2N+1) x π/4
μStepping
6.5
Absolute position counter
An internal 22-bit register (ABS_POS) records the motor motion according to the selected
step mode; the stored value unit is equal to the selected step mode (full, half, quarter, etc.).
The position range is from -2²¹to +2²¹-1 (µ)steps (see Section 9.1.1).
6.6
Programmable speed profiles
The user can easily program a customized speed profile defining independently
acceleration, deceleration, maximum and minimum speed values by the ACC, DEC,
MAX_SPEED and MIN_SPEED registers respectively (see Section 9.1.5, 9.1.6, 9.1.7 and
9.1.8).
When a command is sent to the device, the integrated logic generates the microstep
frequency profile that performs a motor motion compliant to speed profile boundaries.
All acceleration parameters are expressed in step/tick² and all speed parameters are
expressed in step/tick; the unit of measurement does not depend on the selected step
mode. Acceleration and deceleration parameters range from 2^-40 to (2¹²-2)•2^-40 step/tick²
(equivalent to 14.55 to 59590 step/s²).
The minimum speed parameter ranges from 0 to (2¹²-¹)•2^-24 step/tick (equivalent to 0 to
976.3 step/s).
The maximum speed parameter ranges from 2^-18 to (2¹⁰-1)• 2^-18 step/tick (equivalent to
15.25 to 15610 step/s).
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