EVAL6470H Datasheet, PDF (59/70 Pages) STMicroelectronics – dSPIN fully integrated microstepping motor driver with motion engine and SPI

L6470
9.2.6
Programming manual
StepClock (DIR)
Table 42. Stepclock command structure
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2
0
1
0
1
1
0
Bit 1
0
Bit 0
DIR
from host
9.2.7
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).
Move (DIR, N_STEP)
Table 43. Move command structure
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2
0
1
0
0
0
0
X
X
N_STEP (Byte 2)
N_STEP (Byte 1)
N_STEP (Byte 0)
Bit 1
0
Bit 0
DIR
from host
from host
from host
from host
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).
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