Stepper Drivers

Stepper Motor Pulses

Most of the popular Stepper motors used are known as 1.8 degree, which is the resolution of 360 degrees divided by the steps of the motor for one revolution, or worked backwards 360/1.8=200.
So we have to send 200 pulses to get the motor to turn one whole revolution. If we sent 100 pulses then the motor would do half a revolution, which is 180 degrees.

Now even though 1.8 degree sounds a good resolution for simple projects, it becomes a bit restrictive when needing high resolution movements.
But this is not a problem as modern Stepper drivers are known as Micro Step drivers and can increase the resolution from 200 pulses to ten’s of thousands of pulses by some clever electronics.

Controlling a Stepper Motor with a Driver

Not only does the Stepper driver increase the pulses that are needed to do one revolution, but also make control of the motor very simple by offering a Pulse input pin and Direction pin as the interface. You simply send a pulse on the Pulse input to make the motor step the degree resolution you have set on the driver. Then by either supplying 5 volts or 0 volts to the Direction pin will determine if the motor rotates forward or backwards.

Another thing the Stepper driver does is isolate the higher voltage that is needed to run the motor, away from the inputs that are usually TTL logic levels.

Ease of use

Finally the Stepper driver restricts the current that is supplied to the motors, which is usually set using a simple set of switches on the driver.

As you can see, once you have your motors wired up to the drivers and they are all configured, then the next stage is working out how you are going to send and control the pulses to get your motors moving. This is where the PTHAT comes into play as it takes a lot of the complicated stuff away from the developer.

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