L6472H datasheet(26/69 Pages) STMICROELECTRONICS

26 / 69 page

Functional description

L6472

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Doc ID 022729 Rev 1

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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