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Tutorial – L298N Dual Motor Controller Modules and Arduino

Learn how to use inexpensive L298N motor control modules to drive DC and stepper motors with Arduino. This is chapter fifty-nine of our huge Arduino tutorial series.

You don’t have to spend a lot of money to control motors with an Arduino or compatible board. After some hunting around we found a neat motor control module based on the L298N H-bridge IC that can allows you to control the speed and direction of two DC motors, or control one bipolar stepper motor with ease.

The L298N H-bridge module can be used with motors that have a voltage of between 5 and 35V DC. With the module used in this tutorial, there is also an onboard 5V regulator, so if your supply voltage is up to 12V you can also source 5V from the board.

So let’s get started!

L298N Dual Motor Controller Module 2A from Tronixlabs Australia

First we’ll run through the connections, then explain how to control DC motors then a stepper motor. At this point, review the connections on the L298N H-bridge module.

Consider the following image – match the numbers against the list below the image:

L298N Motor Controller for Arduino from Tronixlabs Australia

  1. DC motor 1 “+” or stepper motor A+
  2. DC motor 1 “-” or stepper motor A-
  3. 12V jumper – remove this if using a supply voltage greater than 12V DC. This enables power to the onboard 5V regulator
  4. Connect your motor supply voltage here, maximum of 35V DC. Remove 12V jumper if >12V DC
  5. GND
  6. 5V output if 12V jumper in place, ideal for powering your Arduino (etc)
  7. DC motor 1 enable jumper. Leave this in place when using a stepper motor. Connect to PWM output for DC motor speed control.
  8. IN1
  9. IN2
  10. IN3
  11. IN4
  12. DC motor 2 enable jumper. Leave this in place when using a stepper motor. Connect to PWM output for DC motor speed control.
  13. DC motor 2 “+” or stepper motor B+
  14. DC motor 2 “-” or stepper motor B-

Controlling DC Motors

To control one or two DC motors is quite easy with the L298N H-bridge module. First connect each motor to the A and B connections on the L298N module. If you’re using two motors for a robot (etc) ensure that the polarity of the motors is the same on both inputs. Otherwise you may need to swap them over when you set both motors to forward and one goes backwards!

Next, connect your power supply – the positive to pin 4 on the module and negative/GND to pin 5. If you supply is up to 12V you can leave in the 12V jumper (point 3 in the image above) and 5V will be available from pin 6 on the module. This can be fed to your Arduino’s 5V pin to power it from the motors’ power supply. Don’t forget to connect Arduino GND to pin 5 on the module as well to complete the circuit.

Now you will need six digital output pins on your Arduino, two of which need to be PWM (pulse-width modulation) pins. PWM pins are denoted by the tilde (“~”) next to the pin number, for example:

Arduino UNO PWM pins

Finally, connect the Arduino digital output pins to the driver module. In our example we have two DC motors, so digital pins D9, D8, D7 and D6 will be connected to pins IN1, IN2, IN3 and IN4 respectively. Then connect D10 to module pin 7 (remove the jumper first) and D5 to module pin 12 (again, remove the jumper).

The motor direction is controlled by sending a HIGH or LOW signal to the drive for each motor (or channel). For example for motor one, a HIGH to IN1 and a LOW to IN2 will cause it to turn in one direction, and  a LOW and HIGH will cause it to turn in the other direction.

However the motors will not turn until a HIGH is set to the enable pin (7 for motor one, 12 for motor two). And they can be turned off with a LOW to the same pin(s). However if you need to control the speed of the motors, the PWM signal from the digital pin connected to the enable pin can take care of it.

This is what we’ve done with the DC motor demonstration sketch. Two DC motors and an Arduino Uno are connected as described above, along with an external power supply. Then enter and upload the following sketch:

So what’s happening in that sketch? In the function demoOne() we turn the motors on and run them at a PWM value of 200. This is not a speed value, instead power is applied for 200/255 of an amount of time at once.

Then after a moment the motors operate in the reverse direction (see how we changed the HIGHs and LOWs in thedigitalWrite() functions?).

To get an idea of the range of speed possible of your hardware, we run through the entire PWM range in the function demoTwo() which turns the motors on and them runs through PWM values zero to 255 and back to zero with the two for loops.

Finally this is demonstrated in the following video – using our well-worn tank chassis with two DC motors:

Controlling a Stepper Motor

Stepper motors may appear to be complex, but nothing could be further than the truth. In this example we control a typical NEMA-17 stepper motor that has four wires:

stepper motor Tronixlabs Australia

It has 200 steps per revolution, and can operate at at 60 RPM. If you don’t already have the step and speed value for your motor, find out now and you will need it for the sketch.

The key to successful stepper motor control is identifying the wires – that is which one is which. You will need to determine the A+, A-, B+ and B- wires. With our example motor these are red, green, yellow and blue. Now let’s get the wiring done.

Connect the A+, A-, B+ and B- wires from the stepper motor to the module connections 1, 2, 13 and 14 respectively. Place the jumpers included with the L298N module over the pairs at module points 7 and 12. Then connect the power supply as required to points 4 (positive) and 5 (negative/GND).

Once again if your stepper motor’s power supply is less than 12V, fit the jumper to the module at point 3 which gives you a neat 5V power supply for your Arduino.

Next, connect L298N module pins IN1, IN2, IN3 and IN4 to Arduino digital pins D8, D9, D10 and D11 respectively. Finally, connect Arduino GND to point 5 on the module, and Arduino 5V to point 6 if sourcing 5V from the module.

Controlling the stepper motor from your sketches is very simple, thanks to the Stepper Arduino library included with the Arduino IDE as standard.

To demonstrate your motor, simply load the stepper_oneRevolution sketch that is included with the Stepper library, for example:

L298N motor controller and Arduino tutorial from Tronixlabs Australia

Finally, check the value for

in the sketch and change the 200 to the number of steps per revolution for your stepper motor, and also the speed which is preset to 60 RPM in the following line:

Now you can save and upload the sketch, which will send your stepper motor around one revolution, then back again. This is achieved with the function

Finally, a quick demonstration of our test hardware is shown in the following video:

So there you have it, an easy an inexpensive way to control motors with your Arduino or compatible board. And if you enjoyed this article, or want to introduce someone else to the interesting world of Arduino – check out my book (now in a fourth printing!) “Arduino Workshop”.

visit tronixlabs.com

Have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column, or join our forum – dedicated to the projects and related items on this website.

Posted in arduino, L298, tronixlabs, tronixstuff, tutorial

Part review – Freetronics HBRIDGE motor driver shield for Arduino

Introduction

Controlling motors with an Arduino is a fun and generally integral part of the learning process for most up-and-coming embedded electronics enthusiasts. Or quite simply, using motors is fun ’cause you can make robots, tanks and stuff that moves. And thanks to Freetronics we have their new HBRIDGE motor shield for Arduino to review, so let’s check it out and get some things moving with it.

Arriving in retail-friendly packaging, the HBRIDGE can be stored with the included reusable packaging, and also has a quick-start guide that explains the technical specifications and URLs for tutorials:

HBRIDGE

The shield is compatible with the latest R3-series Arduino boards including the Leonardo and of course the Freetronics Eleven board:

HBRIDGE shield Freetronics Eleven

Specifications

The HBRIDGE shield is based on the Allegro A4954 Dual Full-Bridge DMOS PWM Motor Driver. For the curious, you can download the data sheet (pdf). This allows very simple control of two DC motors with a maximum rating of 40V at 2A, or one bipolar stepper motor. Unlike other motor shields I’ve seen, the HBRIDGE has a jumper which allows the power supply for the motor shield to be fed into the Arduino’s Vin line – so if your motor power supply is under 12V DC you can also power the Arduino from the same supply. Or you can run the motors from the Arduino’s power supply – if you’re sure that you won’t exceed the current rating. Frankly the former would be a safer and this the preferable solution.

The motor(s) are controlled very simply via PWM and digital logic. You feed the A4954 a PWM signal from a digital output pin for motor speed, and also set two inputs with a combination of high/low to set the motor direction, and also put the motor controlled into coast or brake mode. However don’t panic, it’s really easy.

Using the shield

How easy? Let’s start with two DC motors. One example of this is the tank chassis used in Chapter 12 of my book “Arduino Workshop – A Hands-On Introduction with 65 Projects“:

arduino_workshop_tank

The chassis is pretty much a standard tank chassis with two DC motors that run from an internal 9V battery pack. Search the Internet for “Dagu Rover 5” for something similar. Connection is a simple manner of feeding the power lines from the battery and the motor wires into the terminal block on the HBRIDGE shield.

Next, take note of two things. First – the slide switches below the jumpers. Using these you can select the maximum amount of current allowed to flow from the power supply to each motor. These can be handy to ensure your motor doesn’t burn out by drawing too much current in a stall situation, so you can set these to the appropriate setting for your motor – or if you’re happy there won’t be any issues just leave them both on 2A.

The second thing to note is the six jumpers above the switches. These control which digital pins on your Arduino are used to control the motor driver. Each motor channel requires two outputs and one PWM output. If you leave them all on, the Arduino pins used will be the ones listed next to each jumper, otherwise remove the jumpers and manually wire to the required output. For the purposes of our demonstration, we’ll leave all the jumpers in. A final word of warning is to be careful not to touch the A4954 controller IC after some use – it can become really hot … around 160 degrees Celsius. It’s the circled part in the image below:

A4954_controller_IC

So back to the DC motors. You have two digital outputs to set, and also a PWM signal to generate – for each channel. If you set the outputs to 1 and 0  – the motor spins in one direction. Use 0 and 1 to spin the other way. And the value of the PWM (0~255) determines the speed. So consider the following sketch:

Instead of chasing the tank chassis with a camera, here it is on the bench:

Now to try out a stepper motor. You can control a bipolar motor with the HBRIDGE shield, and each coil (pole) is connected to a motor channel.

Hint – if you’re looking for a cheap source of stepper motors, check out discarded office equipment such as printers or photocopiers. 

For the demonstration, I’ve found a random stepper motor from a second-hand store and wired up each pole to a channel on the HBRIDGE shield – then run the Arduino stepper motor demonstration sketch by Tom Igoe:

With the following results:

Considering it was a random stepper motor for which we didn’t have the specifications for – it’s always nice to have it work the first time! For more formal situations, ensure your stepper motor matches the power supply voltage and so on. Nevertheless it shows how easy it can be to control something that appears complex to some people, so enjoy experimenting with them if you can.

Competition

Thanks to Freetronics we have a shield to give away to one lucky participant. To enter, clearly print your email address on the back of a postcard and mail it to:

H-Bridge Competition, PO Box 5435 Clayton 3168 Australia.

Entries must be received by the 20th of  September 2013. One postcard will then be drawn at random, and the winner will receive one H-Bridge shield delivered by Australia Post standard air mail. One entry per person – duplicates will be destroyed. We’re not responsible for customs or import duties, VAT, GST, import duty, postage delays, non-delivery or whatever walls your country puts up against receiving inbound mail.

Conclusion

As demonstrated, the HBRIDGE shield “just works” – which is what you need when bringing motorised project ideas to life. The ability to limit current flow and also power the host board from the external supply is a great idea, and with the extra prototyping space on the shield you can also add extra circuitry without needing another protoshield. Very well done. For more information and to order, visit the Freetronics website. Full-sized images are on flickr. And if you made it this far – check out my new book “Arduino Workshop” from No Starch Press.

tronixstuff

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

Note – The motor shield used in this article was a promotional consideration supplied by Freetronics.

Posted in A4954, freetronics, HBRIDGE, part review, review, stepper motor, tronixstuff, tutorialComments (2)

Kit review – Altronics/Silicon Chip DC to DC Converter

Introduction

Every month Australian electronics magazine Silicon Chip publishes a variety of projects, and in March 2004  they published the “DC-DC converter” project. Altronics picked it up and now offers a kit, the subject of our review. The main purpose of this converter kit is to allow replacement of expensive PP3 9V batteries with 2 AA cells, to enable a cheaper and longer lifespan over use. With a slight modification it can also act as a trickle-charger for 2 rechargeable AA cells (that can then supply power to the converter) via a plugpack. And there’s some educational value if you’re so inclined, as you can learn about voltage converters as well.

Assembly

As usual for Altronics the kit is in a typical retail package:

packaged

…which includes the detailed instructions (based on the original Silicon Chip article), a handy reference guide and of course the parts:

contents

The PCB has a good silk screen and solder mask:

pcbtop

pcbbottom

and all the required parts are included:

components

It was nice to see plenty of extra black and red wire for modifications or final installations, the battery snap, 2 x AA cell holder and a DC socket for use with the optional plug pack mentioned earlier. That hand-wound inductor was interesting, and I couldn’t help but measure it on the LC meter:

lcmeter

It was supposed to be a 47 uH inductor, so let’s hope that doesn’t cause too much trouble. Assembly was quite straight-forward – just start with the smallest components first and build up. If you’re not going to have the trickle-charge function, heed the notes in the manual and don’t install D2 or R4. The only fiddly bit was the “short as possible” (red) link across the board:

longlink

And after a few more minutes it was finished. The external connections will vary depending on your application – however for the review I’ve got the 9V snap on the input, which makes it easy to connect the 2 AA cell holder to power the converter. Nice to see the holes around the perimeter of the board, which make mounting it more permanently quite easy.

Operation

After a bench clean-up it was time to connect 2 AA rechargeable cells and see what we can get out of the converter. The cells measured 2.77V together before connection, and without a load on the converter the resulting output was 8.825 V:

firsttest

We can live with that. Furthermore the quiescent current (a situation with the power connected and not having a load on the output) was 2.5 mA. Thus it would be a good idea to have a power switch in a real-world environment. Speaking of the real world (!) how much current can you get out of the converter? Generally PP3 battery applications are low current, as the battery itself isn’t good for that much – even an expensive “Energizer Ultimate Lithium” offers only 800 mAh (for $16). So using higher-capacity rechargeable AA cells and this kit will save money.  A table is included with the instructions that shows the possible uses:

tableofuse

According to the table my 2.77V supply should be good for ~80 mA. With some resistors in parallel we made a dummy load of 69 mA and measured 0.37A current draw from the AA cells. Thus the key to this kit – you find a cheaper or more plentiful power supply at a lower voltage to save you the expense of providing the higher voltage.

For example, if you had a pair of Sanyo Eneloop rechargeable AA cells (total 2.4 V at 2 Ah) they would give you around 5.4 hours of life (ignoring the fall-off of voltage towards the end of their charge life – however the eneloops are pretty good in that regard). Whereas a disposable PP3 mentioned earlier would offer around 2.1 hours (at $16) or a rechargeable unit (which offers 8.4 V at 175 mAh) would only last around 25 minutes. Note that you can change two resistors in the circuit to alter the output voltage, and the values have been listed in the instructions for outputs up to 15 V.

Finally, let’s consider the output waveforms from the circuit. With the aforementioned load, here’s the output on the DSO:

output

… and for interest’s sake, the switching output from the TL499:

switchoutput

switchoutputdata

Conclusion

Apart from the described voltage-boosting functions this kit gives the interested builder experience with boost circuits and also the knowledge to create their own versions based on the original design, at a much lower cost than using other boost ICs . If you wanted a permanent certain voltage output, it would be better to breadboard the kit and experiment with the required resistors – then assemble the kit with the new values. And there is money and effort to be saved when subsituting with PP3 batteries. Finally, learning is a good thing!

So – a lot of fun and education for under $20. Purchase it from Altronics and their resellers, or read more about it in the September 2007 edition of Silicon Chip.

Full-sized images available on flickr. This kit was purchased without notifying the supplier.

And if you made it this far – check out my new book “Arduino Workshop” from No Starch Press.

LEDborder

In the meanwhile have fun and keep checking into tronixstuff.com. Why not follow things on twitterGoogle+, subscribe  for email updates or RSS using the links on the right-hand column? And join our friendly Google Group – dedicated to the projects and related items on this website. Sign up – it’s free, helpful to each other –  and we can all learn something.

Posted in altronics, boost, converter, dc dc, K6330, kit review, learning electronics, silicon chip, tronixstuffComments (0)


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