1.0 Introduction:

MD30C is the successor of MD30B which is designed to drive medium to high power brushed DC motor with current capacity up to 80A peak and 30A continuously. Fully NMOS design not only provides faster switching time, it is also more efficient and no heatsink or fan is required. MD30C also incorporates some user friendly features such as reverse polarity protection. However, today focus is another user-friendly feature – to use MD30C WITHOUT MICROCONTROLLER! This motor driver with new design contains onboard PWM generator which allows it to generate PWM signal and able to operate without a host controller. This feature is very useful especially in real-time testing and troubleshooting application. Also, if you are not familiar with microcontroller, but wanted to drive a high current motor, you will love this feature.

Now, you don’t have to program and reprogram MCU repeatedly to check for the motor speed and direction, all you need to do is to use onboard switches and potentiometer. furthermore, you can also use your own external switches and potentiometer to achieve the same purpose. So let’s check it out.

2.0 Quick Setup

The components you may need:

3.0 Basic Connection


4.0 How to use it?

First, you are controlling motor in sign-magnitude mode if you operate MD30C without MCU. Potentiometer and switches are used as control devices to control motor speed and direction respectively.

i) Controlling motor direction using onboard switches By doing this, the PWM source is not from MCU(external) but from internal PWM generator, so you have to ensure that  INT PWM  at JP6 is connected using jumper. (EXT PWM refer to the PWM source from external, MCU or external potentiometer).


Now, what you need to do is to press switch A or B on board. Each switch makes motor run in different direction. Remember, press and hold the button to make motor run continuously.


ii) Controlling motor direction using external switches You can use either one SPDT toggle switch or 2 limit switches to do so. In this tutorial, SPDT toggle switch is used as external switch to control motor direction. If user wants to use limit switches instead, please refer to user manual. Connection diagram:


Using this method, only 1 switch is sufficient to testify functionality of motor. However please be aware that once the power is on, the motor will run straight away if the PWM is provided. **Note: There are 2 pins which are shorted (as shown in the figure above) so these 2 pins must be connected to COM. The figures below show some demonstration on controlling motor direction using external toggle switch.


The video below shows how to control motor direction using toggle switch.

iii) Controlling motor speed using onboard potentiometer If you want to control motor speed with onboard potentiometer, make sure that INT POT (internal potentiometer) at JP4 is connected using jumper as shown in figure below.


The video below demonstrates on how to use onboard potentiometer to control motor speed.

iv) Controlling motor speed using external potentiometer Connection diagram:

The video below demonstrates on how to control motor speed using external potentiometer. Makesure jumper at JP4 is being placed at EXT POT and JP6 at INT PWM. Hopefully you learn something from this tutorial.

If you have any question, please do post in Cytron’s technical forum as we seldom check the comment section of tutorial.


3 thoughts on “Using MD30C without MCU”

  1. I want to control direction with a PLC but use on board PWM to control speed. I must be able to use the PWM and DIR terminals to control Direction and On/Off of the motor while the speed is controlled by the internal potentiometer, will this unit work for this ?

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