Beginner questions

Hi!

I’m more of a software guy but want to change this. I’m planning on buying an arduino board to play around, but some questions arise.

First of all, suppose I want to add servo’s and DC motors, why would I need a motor control shield/board? Can’t I connect the servo’s to the arduino board directly?
If for example we write code for the motor control, will it be stored on the motor shield or the arduino board?

I know those questions might seem like ‘omg, is he really asking this?’ but everyone has to start somewhere :smiley:

Thanks in advance!

First of all, suppose I want to add servo's and DC motors, why would I need a motor control shield/board? Can't I connect the servo's to the arduino board directly? If for example we write code for the motor control, will it be stored on the motor shield or the arduino board?

Well what is required for servos and direct motor control are two different things. Servos have motor controllers inside them already so the Arduino only has to supply the control signal and +5vdc power to the servo. By the way powering a servo's +5vdc power conductor directly from a Arduino board is not optimum configuration. An Arduino board has limited regulated +5vdc current capacity and can power only about one servo at best. Depending on the size of the servos, and how many you wish to control one, should plan on using an external regulated +5vdc power supply or batteries. I usually plan on one amp of current capacity per servo.

Simple DC motors can not be driven directly from an Arduino output pin as there is a pin current limit recommendation of 30ma or less. An external DC motor controller allows the external drive capacity of the motor. One has to size the motor controller to the motor's voltage and current ratings.

Good luck with your Arduino projects, it's a great way to learn electronics design and constrution.

Lefty

Thank you for your answer lefty!

I'm trying to build a little tank (as a first project), I'm buying the beginners kit for the arduino board as well as this: http://www.watterott.com/en/Dual-Motor-GearBox http://www.watterott.com/en/Adafruit-Motor-Shield

How do I know if those 2 DC motor's (3-6V) will get enough power from the arduino Duemilanove board?

Thanks in advance!

Welcome to Arduino! I have just done a similar project, making a 2 wheeled robot using the Adafruit motor shield. See the details at http://www.robotliving.com/building-robots/two-wheeled-robot-2.

What you need is the spec sheet for the motors and look for somehting called stall current. My motors have the following specs.

Gear Ratio 1:120 No-load speed(3V):100RPM No-load speed(6V):200RPM No-load current(3V):60mA No-load current(6V):71mA Stall current(3V):260mA Stall current(6V):470mA Torgue (3V): 1.2Kgcm Torque (6V): 1.92Kgcm Size: 55mm x 48.3mm x 23mm Weight:45g

Hi Pauly!

I just noticed the board isn't assembled yet. I don't have any knowledge about soldering so I'll try to follow the guide on your blog post or try to find an assembled shield.

http://www.ladyada.net/make/mshield/solder.html On the end they solder those 6 and 8-header pins, why don't they solder it to the arduino uno too? Or isn't that necessary?

Any shield is seperate and removeable from the Arduino in case you want to use the Arduino for a different project later on.

If you soldered it onto the Arduino it wouldn't be removeable. Good luck with your project.

:)

And yet another step closer to beginning with robotics! I'm strumbeling upon another problem: The dc motors have 1,5V, the beagleboard 2.7 using ogt usbt (automatically) or 5V using the power connector and the arduino board uses 7V.

How can I use thesame power source? Using those thingies: http://www.robotshop.ca/dimension-engineering-3-3V-regulator-1.html ? As there are only 2 wires with a DC, how does this work? Or http://www.robotshop.com/sfe-logic-level-converter.html ?

Thanks again.

Cheers, Stijn

On my setup I have 2 power sources. My Arduino could use a 9 volt battery and outputs 5 volts. But the motors I power using 5 AA batteries, which gives them 7.5 volts, but more amps than a single 9 volt battery.

I wouldn't use the same power source for the Arduino and the motors as motors draw a lot of current.