The OctoDriver is an open-source 8-amp Motor controller. Connect it to your Arduino, Propeller, or PICAxe to control more powerful motors!

I've been working on a dogie door for a while - while the software is straightforward, finding a suitable motor controller has been more difficult.

The problem is that a lot of the inexpensive motor control shields are just too meager to control anything but the most dinky motors.  ladyada's Arduino shield only does 600mA continuous, 1.1A peak . Pololu makes beefier motor controllers, the DMC 01 can do 13 amps, but it's pretty expensive (about $100). 

So I've been on the lookout for a high power, inexpensive, and easy to control circuit - I was flipping through starlino's website and I spotted exactly what I was looking for. His idea is pretty simple: why not combine 2 motor controller IC's to split the load?

He calls the circuit the 'OctoDriver', it combines 2 h-bridges to provide 8 amps peak, 4 amps continuous. I asked him if I could put it on a PCB, and he thought it was a great idea. I couldn't think of a better name, so I call my version "The OctoDriver".

I also put it on a Propeller Platform compatible footprint, so it can be used on a breadboard, perfboard or with a Propeller microcontroller. The design is available under the MIT license, so anyone is free to hack away.

The OctoDriver is also available as a kit from Gadget Gangster.

Flip to the next step and I'll give you some more technical details on the OctoDriver and show you how to use it.

Step 1: FAQ

What are the Specs?
The OctoDriver is an 8 amp motor controller, capable of controlling 2 motors @ 8 amps. It uses four TI SN754410 (datasheet) Quad Half-H drivers, 2 per motor. The SN754410 is 'juiced-up' version of the classic L293D. Here are the key specs of the OctoDriver

OctoDriver Specs  
Peak Current: 8A
Continuous Current: 4A
Motor Voltage: 4.5V - 36V
Logic Voltage: 5 Vdd, inputs will accept 2.0v - 5.5v
Operating Temp:  -40c to 85c (-40f to 176f)
Motor Support:
2 Bi-directional DC motors / linear actuators, or 1 stepper
Other Features: ESD Protection, Thermal Shutdown, No 'Power Up Glitch'
Connectivity: .1" pin spacing for Breadboard / Protoboard. 2 OctoDrivers can be stacked on a single Propeller Platform, as well.

I didn't include servo headers because it's super easy to connect a servo to a Prototyper module and controlling servos with a Propeller is easy, too.

Do I really need that much power?
When you check out the specs on a standard servo, it's often something like 150mA. So what's the point of a 4+ amp motor driver?

Here's the deal - that 'current-draw' number is at NO LOAD. In other words, if you actually wanted to move something with the motor, your current-draw will be higher.  How much higher depends on your load, but the highest draw would be if the motor were stalled (Stall Current).

Take this typical servo. With a 6V power source, no-load draw is a measly 220mA... until you actually make it move something! Maxing it out brings you to 1.3 amps of current draw. And that's a ONE standard servo.

Moving anything but the smallest motor requires real power, and 800mA bridge doesn't cut it.

Will the OctoDriver work with Arduino / PICAxe / Workbench 1.3?
Yes. Using it is super-simple. At the end of this howto, I'll show you how it's done.

Is it hard to build?
No - it's really easy to put together. If this is your first time soldering, it will probably take 15 minutes. If you're a seasoned pro, it should take longer for your soldering iron to warm up than assemble.

Here's a video demo of Starlino's OctoDriver in action:

could it be made as a 12a dual motor driver if yeas wat changes should be made
<p>SUH-WEET!!! I'm on it!!! Much Thanks!</p><p>wonderin' if this would drive a single 24 VDC scooter motor ? the batteries that run it are 2-12 vdc 10 AH....wuddya think? though I know I dont need the &quot;Octo- &quot; dual aspect of this instructable, I too cant find anything beefy enuff to safely drive that motor. Thanks for ANY input!!</p>
Great Project!!! I would love to build this project with the PCB you had listed on your website. I signed up to be notified if and when the board will be available. Do you know if we can still purchase it or is it a discontinued item?
I am planning to buy a new DC motor driver board which can run 5amp motor but I don't know how to connect it with Atmega 8A chip. Please see the pdf I attached for Atmega 8A.<br> <br> Here are the 7 pins in DC motor controller:-<br> <br> Pin No. Pin Functionality<br> 1 GND Ground<br> 2 IN-1 Logic input for the motor direction.<br> 3 Diagnostic 1<br> (DG-1) Output pin with logic 1 output in normal operation. Represents side of the internal<br> H bridge corresponding to IN-1. Pin is pulled to logic low by the motor driver in<br> case of over temperature or overload due to short circuit.<br> 4 PWM Used to apply Pulse Width Modulation to control motor velocity<br> 5 Diagnostic 2<br> (DG-2) Output pin with logic 1 output in normal operation. Represents side of the internal<br> H bridge corresponding to IN-2. Pin is pulled to logic low by the motor driver in<br> case of over temperature or overload due to short circuit.<br> 6 IN-2 Logic input for the motor direction.<br> 7 CS* Current Sense output to measure the current flowing through the driver
Questions from a newbie. Would it be possible to increase the amperage&nbsp; by using something beefier than the TI SN754410? My project is to control a pair of motors (from a scooter chair) to power a small boat.<br />
At that point, you probably better off using a mosfet powered controller - BJT based H-bridges are going to waste too much heat for your application.&nbsp; Check Pololu for some nice ones.<br />
Great Project. I&nbsp;have been stuck in the same boat really looking for a motor driver. My next real option for power was to build a H-Bridge circuit from Mosfets, which would give me tons of power but at a high price :(<br /> <br /> Im going to run down to Jaycar tomorrow and pick up the parts and get it breadboarded up for my Arduino<br /> <br /> Good stuff :)<br /> John<br />
Fantastic project! any thoughts on open-sourcing the complete schematic/board layout files?&nbsp; Looks complex to diy the circuit board, not not impossible :D<br /> <br /> Silly question:&nbsp;&nbsp;Those traces look a bit small to handle 8amps at 5 volts...I'm guessing that gets proportionally less to suit the max motor voltage (to match the total wattage...)<br />
Thanks! It was a lot of fun putting it together and testing it. I threw some fairly massive softball-sized motors and it worked like a champ.<br /> <br /> I'm working on a battery pack for the Propeller Platform, too - so the next step will be to put the OctoDriver in a wheel robot with some UPS&nbsp;batteries, running the Prop logic on a separate battery.<br /> <br /> The schematic / layout files are under the MIT license (essentially public domain) - there's a link to download it in PDF or diptrace format on the last step.&nbsp; Same deal with the Propeller object.<br /> <br /> The board uses thicker (taller) traces than usual to support extra current (4 oz instead of 1 or 2) - it will do just fine providing 4 amps continuous to each motor 8 amp peaks are fine, too.<br />
Thanks for the quick reply!&nbsp;&nbsp;Really neat stuff; I&nbsp;never realised the dip link was another format :)&nbsp;silly me!<br />
No problem!&nbsp; Diptrace is my favorite program - there's a freeware version that works just fine, too.<br />
&nbsp;Top goal!

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