Driver for stepper motor
The Stepper Motor Driver block represents a driver for a stepper motor. It creates the pulse trains, A and B, required to control the motor. This block initiates a step each time the voltage at the ENA port rises above the Enable threshold voltage parameter value.
If the voltage at the REV port is less than or equal to the Reverse threshold voltage parameter value, pulse A leads pulse B by 90 degrees. If the voltage at the REV port is greater than the Reverse threshold voltage value, pulse B leads pulse A by 90 degrees and the motor direction is reversed.
At time zero, pulse A is positive and pulse B is negative.
If you set the Stepping mode parameter
Half stepping, the Stepper Motor
Driver block can produce the output waveforms required for
half stepping. In this mode, there is an intermediate state between
the full steps, in which just one of the A or the B half-windings
is powered. As a result, the step size is half of the stepper motor’s
full step size. At half steps, windings that are not powered are short-circuited.
This approximates the effect of a freewheeling diode connected across
If you set the Simulation mode parameter
Averaged, both for a Stepper
Motor Driver block and for the Stepper Motor block
connected to it, then the individual steps are not simulated. This
can be a good way to speed up simulation. The Averaged mode assumes
that the external controller provides a step rate demand. This step
rate demand is determined from the voltage applied between the ENA
and REF ports on the Stepper Motor Driver block, by
multiplying this voltage by the value of the Step rate sensitivity parameter.
The rotation direction is set by the REF port in the same way as for
the Stepping mode.
Averaged mode needs to communicate the step rate demand and also output voltage amplitude information to the Stepper Motor block. To do this, the step rate demand is applied as an equivalent voltage across the A+ and A- ports. Similarly the output voltage amplitude information is conveyed by applying a steady-state voltage across the B+ and B- ports with value equal to the Output voltage amplitude parameter.
The model is based on the following assumptions:
To use Averaged mode, the Stepper Motor Driver block must be directly connected to a Stepper Motor block also running in Averaged mode.
When changing from Stepping to Averaged mode and back, you will need to modify your upstream blocks that provide the input voltages to the Stepper Motor Driver. One way to achieve this easily is to use Simulink® variant subsystems.
Averaged only if the block is connected
directly to a Stepper Motor block also running in Averaged mode. The
default value is
When the voltage at the ENA port rises above this threshold,
the Stepper Motor Driver block initiates a step. This
parameter is visible only if Simulation mode is
Stepping. The default value is
This parameter converts the voltage presented across the ENA
and REF ports into a step rate demand. This parameter is visible only
if Simulation mode is set to
The default value is
10 steps-per-second per volt.
When the voltage at the REV port rises above this threshold,
pulse B leads pulse A by 90 degrees, and the motor direction is reversed.
The default value is
Amplitude of the output pulse trains. The default value is
Full stepping or
stepping. The default value is
The block has the following ports:
Positive electrical output of pulse A
Negative electrical output of pulse A
Positive electrical output of pulse B
Negative electrical output of pulse B
Triggering input step voltage
Input floating reference voltage
Input voltage that controls motor direction