# Simple Motor Controller RPM

Hi,

I am looking at using a 24v23 simple motor controller with an Arduino board, to make a PID controller for a small test rig. The motor needs to be set up to a maximum speed of 700 RPM, and multiple speeds within this range from 0 RPM. From the motor controller data sheet, the speed should be a number from -3200 to 3200. I was wondering what these numbers correspond to, is is just RPM? Only I couldn’t find any data to clarify this. I just wanted to double check that this rotational speed could be achieved before I purchase the board. The current draw of the motor is well within specification.

Hi,

I’m looking to use a 24v23 simple motor controller with an Arduino to make a PID controller for a small test rig. With a rotational speed range of 0 to 700 RPM.

From the motor controller data sheet, the speed should be a number from -3200 to 3200. Does this value correspond to RPM/pulses? I just want to check that the broad is acceptable for my requirements before I purchase it.

Sorry for such a basic question

Many thanks for you help

Hello.

The Simple Motor Controller controls the speed by changing effective voltage applied to the motor using a PWM signal. Motor speed for a brushed DC motor is directly proportional to the applied voltage. The maximum speed value of 3200 that the Simple Motor Controller uses just represents the 100% duty cycle (or maximum applied motor voltage). You can reduce the value to reduce the effective voltage and thus the speed and set a negative value to reverse the motor’s direction. For example, if you had an input voltage of 12V and you set the speed to 1600 the effective voltage applied to the motor would be 6V (1600 is half of 3200 and 6V is half of 12V).

By the way, the Simple Motor Controller is open loop, so if you apply a torque to the motor the speed will be reduced (e.g. a set speed of 1600 might result in 40% speed rather than 50%). If you are looking for precise speed control, you will want to add some sort of feedback like an encoder to the motor.

- Grant