Hi
I'm still doing some pre-planning for an arduino project and I'm trying to figure out what parts exactly I am going to use.
I think I'm going to go for a simple obstacle avoidance robot and if successful, maybe I'll try to extend it to a maze solving one (a just-get-out-of-the-maze thing using the right-hand method).
I'm planning of using two stepper motors (for a chassis with two wheels), a servo motor and a ultrasonic sensor.
So, here are my questions:
a) How do I power multiple parts from the battery?
b) If at some point I need to store data, would an SD card reader module be sufficient?
For any parts suggestions, I'd appreciate links to the arduino.cc store, here.
All of the motors will need to be powered directly from the battery and NOT through the Arduino board.
The motors will probably need different voltages. It is common to power stepper motors with relatively high voltages through a proper stepper motor driver board such as the Pololu A4988. You will have to do some research on this to decide what motors and battery are appropriate. Servos usually work at 5 volts but NOT the 5 volts from the Arduino board. If you have a higher voltage battery for the stepper motors you may be able to use something like a 7805 voltage regulator to produce suitable voltages for the Arduino and the servo (I suggest 2 separate 7805s). Or you could use separate batteries for everything each sized appropriately.
Whatever you do make sure that the battery(ies) have sufficient capacity. Don't even think of using a PP3 9v battery for any part of it.
Robin2:
All of the motors will need to be powered directly from the battery and NOT through the Arduino board.
I presume this is not your first Arduino project.
Those are good points - this is not something you want to attempt for your very first "own design" project. I suggest experimenting with a kit project first - you can buy robot kits for exactly what you're talking about, and that way you learn how to wire up things, without risking burning out your hardware, and you get a set of parts that all go together and a platform you can expand on more easily.
Have you tried any of these kits? Or at least pull the schematics and code, to get an idea... http://arduino.cc/en/Main/Robot - this one is really neat because it's "official" Arduino, but it's a little complicated.
https://www.sparkfun.com/products/9211 - this would be an excellent learning platform, but I think the sensors it has are a little odd - a kit with many different types of sensors would be better.
Robotics Shield Kit for Arduino - Parallax - ROB-11494 - SparkFun Electronics - kinda expensive but a good platform to start with - you must provide your own Arduino, so will help learn some basic wiring. It includes lessons for working with three different types of sensors, but does not include those sensors - so, yet another opportunity to learn wiring.
Yes, this is my first project and even though I know it's going to be quite a task, I mean to give it a shot. Asking, searching the Web etc. I'm determined to figure it out, eventually.
After reading your posts I searched and found this page which seems to be quite explanatory.
So, see if I get this right: the arduino board could better have its very own battery source while the stepper and servo motors could all use one 9v battery (with 7805 regulators used wisely). Something like this?
So, see if I get this right: the arduino board could better have its very own battery source while the stepper and servo motors could all use one 9v battery (with 7805 regulators used wisely). Something like this?
First part is correct, an arduino board works best if it's using a dedicated voltage source, like a battery, USB power, or a DC power supply. The second part is quite a stretch as those small 9 volt batteries do not have enough current capacity to power servos and most any practical DC motor.
I especially made the point in Reply #1 that you should NOT use a PP3 9v battery.
Don't even try it as you will run into all sorts of strange problems that won't seem to a newbie to be related to a lack of power and you will just be back here asking what's the problem with my code.
The second part is quite a stretch as those small 9 volt batteries do not have enough current capacity to power servos and most any practical DC motor.
Is why you don't use those 9V batteries, they will not supply the arduino with enough CURRENT.
I remember when they were called transistor batteries, the reason was and still is they can only provide enough power for a handful of transistors.
MrDimitris:
ok, Robin2.. I'll follow your advice.. How come there will be lack of power, though, since it's a 9v battery?
Because a batteries voltage and a batteries power are two different parameters for a specific battery type.
1.5 volt batteries come in many sizes AAA, AA, C, D, do you suppose that they all contain the same amount
of power? Power is the product of voltage and current, so you must come to terms with ohm's law to gain
understanding.
MrDimitris:
I'm trying to gain a better understanding on batteries, right now. This article here is quite helpful.
I like that article, it helps people understand the details around this subject. Many people have trouble differentiating rates and amounts, and the more you can read, the better. I've never been happy with the labeling on consumer batteries - they really should put the C rating. Over in the aircraft world, we would never use a battery without knowing that.
retrolefty:
1.5 volt batteries come in many sizes AAA, AA, C, D, do you suppose that they all contain the same amount
of power?
Although there was a thread recently in which is was suggested that they do.... one manufacturer seems to package small cells in big housings.
Quite common for 'some' rechargeable D cells to contain C size cells internally. One really has to look at the mAH ratings for a specific battery and if the spec is not given then "buyer beware" applies.
