MC1151A PMD, MC1151A Datasheet - Page 22

• Manufacturer Part Number: MC1151A
• Description: (MC1x51A) Advanced Step Motor Control Chipset
• Manufacturer: PMD

specified acceleration rate, until a velocity of zero is reached. In
addition the form of the deceleration is symmetric to the acceleration
phase. For example if the profile mode is S-curve, and a
SMOOTH_STOP command is given, the profile will decelerate in a
manner exactly equal and opposite to the acceleration phase.
The STOP command functions in all profile modes; S-curve point-
to-point, Trajectory point-to-point, Velocity Contouring, and
Electronic Gear.
The SMOOTH_STOP functions in S-curve point-to-point,
Trajectory point-to-point, and Velocity Contouring profiling mode.
It does not function in Electronic Gear mode.
Caution should be exercised when using the STOP command due
to the large and abrupt changes in motion that may occur.
Motion Complete Status
To simplify the programming of a complete motion system it is
convenient to have the motion chipset indicate when a particular profile
move has been completed.
This function is provided by two status bits in the chipset's status word
(See the section of this manual entitled "Axis Status " for more
information on the axis status word). These two bits are called the
motion complete bit, and the in-motion bit.
The motion complete bit is controlled interactively by the chipset and
the host. After a motion has completed, the chipset sets the motion
complete bit on. The host may then poll this bit to determine that motion
is complete, or if desired, the host can program the chipset to
automatically signal when the motion is complete (using an interrupt). In
either case once the host has recognized that the motion has been
completed the host clears the motion complete bit, enabling the bit to
indicate the end of motion for the next move.
The following list shows the conditions that will cause the motion
complete bit to occur:
The in-motion bit is similar to the motion complete bit except that it
continuously indicates the status of the axis without interaction with the
host. In addition this bit is used exclusively for polled mode operations.
It can not cause an interrupt to the host to be generated.
The motion complete and the in-motion indicator bits function in
the S-curve point-to-point, Trapezoidal point-to-point, and Velocity
-
-
-
-
-
Profile has reached the destination position (point-to-point
profile modes only)
Axis trajectory reaches a velocity of zero and the current
velocity command is zero
SMOOTH_STOP command is given and axis trajectory
reaches a velocity of zero
STOP command is given
Limit switch condition occurs
22
Contouring profile modes only. They do not function when the
profile mode is set to electronic gearing.
The motion complete and in-motion bits indicate the state of the
trajectory generator, not the actual motor. Even if the trajectory
generator has completed a motion, the actual axis position may or
may not be at rest depending on motor stability, and other system
conditions.
Parameter Loading & Updating
Various profile & motor control parameters must be specified by the
host for an axis to be controlled in the desired manner. To facilitate
precisely synchronized motion, these parameters and related control
commands are loaded into the chip using a double-buffered scheme. In
this scheme, the parameters and action commands being loaded are
not acted upon (copied from the double-buffered to the active registers)
until an update signal is given.
This update signal can consist of either a "manual" update command or
one of several conditional breakpoints. Whichever update method is
used, at the time the update occurs, all of the double buffered registers
and commands will be copied to the active registers. Conversely,
before the update occurs, loading the double-buffered registers or
executing the double buffered commands will have no effect on the
system behavior.
The double buffered registers are listed below.
Register Name
destination position
maximum velocity
acceleration
maximum acceleration
jerk
ratio
buffered motor command
The double-buffered commands are: STOP, SMOOTH_STOP, and
SYNCH_PRFL.
Manual Update
There are two methods of manually updating the double-buffered
parameters & commands, one for a single axis instantaneous update
and one for a multiple-axis update.
The single axis instantaneous update, which is specified using the
UPDATE command, forces the parameters for the current axis to be
updated at the next cycle.
The multiple axis instantaneous update, which is specified using the
MULTI_UPDATE command, causes multiple axes to be updated
simultaneously. This can be useful when synchronized multi-axis
profiling is desired. This command takes a 1 word argument which
Command to set
SET_POS
SET_VEL
SET_ACC
SET_MAX_ACC
SET_JERK
SET_RATIO
SET_BUF_MTR_CMD