L6482 Datasheet, PDF (63/73 Pages) STMicroelectronics – cSPIN™: microstepping motor controller with motion engine and SPI

L6482
9.2.5
Programming manual
This command reads the current PARAM register value; PARAM is the respective register
address listed in Table 11.
The command response is the current value of the register (most significant byte first). The
number of bytes composing the command response depends on the length of the target
register (see Table 11).
The returned value is the register one at the moment of GetParam command decoding. If
register values change after this moment, the response is not updated accordingly.
All registers can be read anytime.
Any attempt to read an inexistent register (wrong address value) causes the command to be
ignored and the WRONG_CMD flag to rise at the end of the command byte as if an
unknown command code were sent.
Run (DIR, SPD)
Table 51. Run command structure
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3
0
1
0
1
0
X
X
X
X
SPD (Byte 1)
SPD (Byte 0)
Bit 2 Bit 1
0
0
SPD (Byte 2)
Bit 0
DIR
from host
from host
from host
from host
Note:
9.2.6
The Run command produces a motion at SPD speed; the direction is selected by the DIR
bit: '1' forward or '0' reverse. The SPD value is expressed in step/tick (format unsigned fixed
point 0.28) that is the same format as the SPEED register (Section 9.1.4).
The SPD value should be lower than MAX_SPEED and greater than MIN_SPEED,
otherwise the Run command is executed at MAX_SPEED or MIN_SPEED respectively.
This command keeps the BUSY flag low until the target speed is reached.
This command can be given anytime and is immediately executed.
StepClock (DIR)
Table 52. 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
The StepClock command switches the device in Step-clock mode (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 (Section 6.7.5 and 9.1.21).
The device exits Step-clock mode when a constant speed, absolute positioning or motion
command is sent through SPI. Motion direction is imposed by the respective StepClock
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