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Microstep Waveform Generation
48
Juno Step Motor Control IC User Guide
8
Whether via pulse & direction, SPI, or internal profile generation, to minimize the chance of spurious movement
during startup, by default Juno disables position command input processing. This setting is controlled via the
command source flag of the Operating Mode register and can be user programmed. See
for more information on how to set this flag.
8.2
Microsteps Per Full Step
The overall sinusoidal waveform is broken into discrete microstep positions, with the number of microsteps per full
step (a full step is one quarter of a full electrical cycle) being user settable. Each microstep represents a discrete
addressable position of the step motor, and thus the greater the number of microsteps per full step the greater the
number of resolvable motor positions.
The number of microsteps per full step is specified using a register known as the phase counts register. The phase
counts setting represents the number of microsteps per electrical cycle (four times the desired number of microsteps
per full step).
Example
If a 1.8° step motor (1.8° of motor rotation per full step) is set up with a resolution of 64 microsteps per full step the
phase counts setting will be 64 x 4 = 256, and the number of resolvable positions per mechanical rotation will be 360°
/ 1.8° x 64 = 12,800 microsteps per motor rotation. Note that this represents the theoretical positioning resolution
but does not necessarily mean the motor will have this precision or even this number of actual resolved mechanical
positions. That depends on a number of application characteristics including system friction, drive, torque, and motor
linearity.
The minimum number of microsteps per full step is one (phase counts setting of four). The maximum number of
microsteps per full step is 256 (phase counts setting of 1,024).
8.3
Drive and Holding Current
A user-specified drive current controls the amplitude of the microstepping waveform. Depending on whether the
current loop module is enabled the provided drive current value will express either a current or a voltage. With the
current loop active a drive current command of, for example, 100% will command the highest possible available
current to the motor. With the current loop not active (Juno operating in voltage mode) a 100% drive current
command will command the highest possible available voltage.
For information on converting commanded current values to actual delivered amps at the motor refer to
Juno ICs provide an
AtRest
signal input which is used to indicate whether the axis is in motion. In conjunction with
this signal a separate holding current command can be defined which is applied when the
AtRest
signal is active. A bit
indicating whether the axis is currently in a holding condition is available in the Drive Status register.
To activate position command processing the command source flag of the Operating Mode register must be en-
abled.
Содержание Juno MC71112
Страница 12: ...The Juno IC Family 12 Juno Step Motor Control IC User Guide 1 This page intentionally left blank ...
Страница 18: ...Functional Characteristics 18 Juno Step Motor Control IC User Guide 2 This page intentionally left blank ...
Страница 22: ...Electrical Characteristics 22 Juno Step Motor Control IC User Guide 3 This page intentionally left blank ...
Страница 26: ...Timing Diagrams 26 Juno Step Motor Control IC User Guide 4 This page intentionally left blank ...
Страница 46: ...Operational Overview 46 Juno Step Motor Control IC User Guide 7 This page intentionally left blank ...
Страница 54: ...Microstep Waveform Generation 54 Juno Step Motor Control IC User Guide 8 This page intentionally left blank ...
Страница 70: ...Internal Profile Generation 70 Juno Step Motor Control IC User Guide 11 This page intentionally left blank ...
Страница 78: ...Motion Monitoring Control 78 Juno Step Motor Control IC User Guide 12 This page intentionally left blank ...
Страница 86: ...Drive DC Bus Safety 86 Juno Step Motor Control IC User Guide 13 This page intentionally left blank ...
Страница 100: ...Application Notes MC74113 MC75113 100 Juno Step Motor Control IC User Guide 15 Figure 15 3 Drive Safety and Monitoring ...
Страница 103: ...Application Notes MC74113 MC75113 Juno Step Motor Control IC User Guide 103 15 Figure 15 4 Leg Current Sensing ...
Страница 114: ...Application Notes MC74113 MC75113 114 MC58113 Electrical Specifications 15 This page intentionally left blank ...