L6470PD datasheet(59/70 Pages) STMICROELECTRONICS

59 / 70 page

L6470

Programming manual

Doc ID16737 Rev 5

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9.2.6

StepClock (DIR)

The StepClock command switches the device in Step-clock mode (see Section 6.7.5) and

imposes the forward (DIR = '1') or reverse (DIR = '0') direction.

When the device is in Step-clock mode, the SCK_MOD flag in the STATUS register is raised

and the motor is always considered stopped (see Section 6.7.5 and 9.1.22).

The device exits from Step-clock mode when a constant speed, absolute positioning or

motion command is sent through SPI. Motion direction is imposed by the respective

StepClock command argument and can by changed by a new StepClock command without

exiting Step-clock mode.

Events that cause bridges to be forced into high impedance state (overtemperature,

overcurrent, etc.) do not cause the device to leave Step-clock mode.

The StepClock command does not force the BUSY flag low. This command can only be

given when the motor is stopped. If a motion is in progress, the motor should be stopped

and it is then possible to send a StepClock command.

Any attempt to perform a StepClock command when the motor is running causes the

command to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

9.2.7

Move (DIR, N_STEP)

The Move command produces a motion of N_STEP microsteps; the direction is selected by

the DIR bit ('1' forward or '0' reverse).

The N_STEP value is always in agreement with the selected step mode; the parameter

value unit is equal to the selected step mode (full, half, quarter, etc.).

This command keeps the BUSY flag low until the target number of steps is performed. This

command can only be performed when the motor is stopped. If a motion is in progress, the

motor must be stopped and it is then possible to perform a Move command.

Any attempt to perform a Move command when the motor is running causes the command

to be ignored and the NOTPERF_CMD flag to rise (see Section 9.1.22).

Table 42.

Stepclock command structure

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

01100

DIR

from host

Table 43.

Move command structure

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

DIR

from host

N_STEP (Byte 2)

from host

N_STEP (Byte 1)

from host

N_STEP (Byte 0)

from host

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