L6472 Datasheet, PDF (26/69 Pages) STMicroelectronics – dSPIN fully integrated microstepping motor driver

Functional description
L6472
6.7.6
GoUntil and ReleaseSW commands
In most applications the power-up position of the stepper motor is undefined, so an
initialization algorithm driving the motor to a known position is necessary.
The GoUntil and ReleaseSW commands can be used in combination with external switch
input (see Section 6.13) to easily initialize the motor position.
The GoUntil command makes the motor run at the target constant speed until the SW input
is forced low (falling edge). When this event occurs, one of the following actions can be
performed:
● ABS_POS register is set to zero (home position) and the motor decelerates to zero
speed (as a SoftStop command)
● ABS_POS register value is stored in the MARK register and the motor decelerates to
zero speed (as a SoftStop command).
If the SW_MODE bit of the CONFIG register is set to e0f, the motor does not decelerate but
it immediately stops (as a HardStop command).
The ReleaseSW command makes the motor run at the programmed minimum speed until
the SW input is forced high (rising edge). When this event occurs, one of the following
actions can be performed:
● ABS_POS register is set to zero (home position) and the motor immediately stops (as a
HardStop command)
● ABS_POS register value is stored in the MARK register and the motor immediately
stops (as a HardStop command).
If the programmed minimum speed is less than 5 step/s, the motor is driven at 5 step/s.
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Doc ID 022729 Rev 1