Driver Modules

Modules

We finished the discussion on motor driver chip, So now I want to talk about motor driver modules. What I mean by module are the circuit boards with driver chips already installed. Again there are many vendors, but as you can see below I have a few favorites that I keep using.

Pololu

Pololu Single Motor Driver

Pololu makes several modules. They categorize them as motor controllers and motor drivers. The difference being that motor controllers have some on board processing and take a serial command, analog voltage, or RC servo signal as an input. The motor drivers on the other hand are just carrier boards for the driver ICs with the required support components. You will still need to supply your own digital control signals. Pololu makes their modules with some of the chips I have already mentioned, like the MC33887 and VNH2SP30. They also have some real high current drivers made with MOSFETs. They can handle 10 amps or more. I am not using big motors so the higher current units are way more than I need.

Sparkfun

Sparkfun Dual Motor Driver

Again, Sparkfun has many driver modules, so many it would be a waste of time to list them here. It is interesting to note that besides the units Sparkfun makes, they also sell modules from other companies like Pololu and Solarbotics. Sparkfun makes motor drivers with simple logic, serial, and analog voltage interfaces. Basically you get the same kind of interfaces that Pololu has, just a wider selection of modules. In addition they have a OpenServo module for replacing the electronics in your servos. It uses a different interface than the standard RC servo control signal. Anyway, take a look at their website as I am sure you’ll find something you like. Looking at Sparfun’s website I always come away with a new idea of something to build.

Solarbotics

Solarbotics Motor Driver

Solarbotics is a company that sells many BEAM style robot kits and accessories. They carry a line of motor drivers from Phidgets and Dimension Engineering in addition to their own units. Solarbotics makes a L298 driver module and a L293D servo electronics replacement module. The Phidget and Dimension Engineering modules are well designed and have a professional look about them. You’ll have to decide on your own if you want these type of modules since they are a little expensive. Cost is relative to the project, so for your creation it might be worth it.

Driving a Speaker

So I am doing all this talking about driving motors, but there is another inductive load I like to drive – a speaker! At Mini Sumo competitions it is not required to have any indication of the 5 second countdown before your robot is allowed to move. You do get a better crowd reaction if you do. Most robots blink an LED to indicate the 5 seconds. Other produce a beep for the same reason. I am thinking of having a series of tones to indicate the count down. I just think it would be one of those “cool” factors I talked about in another post.

I plan to over design the audio circuit for driving a speaker. From the output from the microcontroller I will use a resistor/capacitor filter to change the squarewave into a sinewave. Then the signal will pass through a LM358 op-amp so I can provide a little “coloring” to the audio signal. Finally I will send the signal to a LM386 power amplifier to drive the speaker. This circuit is really just for fun as it serves no other function.

So what is coming next… I will talk about some of the final design decisions and start creating the schematic. I will go over some of your schematic capture options. After that I will give you a bit more information about mini sumo and how it affects my design decisions. Until then, see you.

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