Datasheet

L6470 Programming manual
Doc ID16737 Rev 5 61/70
9.2.10 GoUntil (ACT, DIR, SPD)
The GoUntil command produces a motion at SPD speed imposing a forward (DIR = '1') or a
reverse (DIR = '0') direction. When an external switch turn-on event occurs (see
Section 6.13), the ABS_POS register is reset (if ACT = '0') or the ABS_POS register value is
copied into the MARK register (if ACT = '1'); then the system performs a SoftStop command.
The SPD value is expressed in step/tick (format unsigned fixed point 0.28) that is the same
format as the SPEED register (see Section 9.1.4).
The SPD value should be lower than MAX_SPEED and greater than MIN_SPEED,
otherwise the target speed is imposed at MAX_SPEED or MIN_SPEED respectively.
If the SW_MODE bit of the CONFIG register is set low, the external switch turn-on event
causes a HardStop interrupt instead of the SoftStop one (see Section 6.13 and 9.1.21).
This command keeps the BUSY flag low until the switch turn-on event occurs and the motor
is stopped. This command can be given anytime and is immediately executed.
9.2.11 ReleaseSW (ACT, DIR)
The ReleaseSW command produces a motion at minimum speed imposing a forward (DIR =
'1') or reverse (DIR = '0') rotation. When SW is released (opened), the ABS_POS register is
reset (ACT = '0') or the ABS_POS register value is copied into the MARK register (ACT =
'1'); the system then performs a HardStop command.
Note that resetting the ABS_POS register is equivalent to setting the HOME position.
If the minimum speed value is less than 5 step/s or low speed optimization is enabled, the
motion is performed at 5 step/s.
The ReleaseSW command keeps the BUSY flag low until the switch input is released and
the motor is stopped.
Table 46. GoUntil command structure
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
1 0 0 0 ACT 0 1 DIR from host
X X X X SPD (Byte 2) from host
SPD (Byte 1) from host
SPD (Byte 0) from host
Table 47. ReleaseSW command structure
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
1 0 0 1 ACT 0 1 DIR from host