Confusion about taking Arduino past prototyping

Using Arduino Project Guidance
#1

I'm a web designer who's trying to get into physical computing. I bought the Arduino and have been doing a lot of reading, but while I can follow a tutorial and make something work on a breadboard I still don't understand some key concepts. The biggest one is how exactly do you take this blinking LED off of the breadboard? I'm not sure how to bridge the gap from an Arduino that's plugged into a computer and dependent on a breadboard to something that stands on it's own and is run by batteries or a power source. Is it an involved process to turn your prototype into a standalone device?

I really appreciate any input.

#2

There are several levels of standalone Arduino hardware.

The first is put the Arduino and your breadboard in a box with a battery. That isn't hard to understand? The arduino has a 7 to 12V raw power input socket and on-board 5V regulator

Secondly if everything you need is available as a shield you can stack them, put in a box.

Thirdly you can then move to mounting everything from the breadboard onto stripboard and permanently connect (maybe using plugin headers for any breakout modules)

The most complete way is to design a PCB with everything on it (including the 328 microcontroller, crystal etc) and create a single board that is dedicated to the function. This is how mass production would be done but usually needs surface mount technology (less easy to solder yourself) Examples include the Rainbowduino.

#3

I apologize in advance because I am completely new/ignorant to any form of electrical work and engineering:

What I think that I'm hearing is the Arduino alone isn't enough to power a project. It needs some form of a circuit board, like a breadboard, shield, or PCB? I'm just confused about where the soldering comes in and more assembly-based aspects of the Arduino. It seems like all of the how-tos I'm seeing involve coding and working off a breadboard. One tutorial I saw didn't seem to mention any shield or form of circuit board. The programming in examples like these http://meandollie.com/make/part-2/ are very easy to understand, but the mechanical end always seems to be left out. Not sure if it's so basic it doesn't need to be explained?

Is there any good reading material out there for someone like me who understands code very well, but is lost on the electrical end?

#4

The Arduino is just a microcontroller - any peripherals you want to control (sensors, LEDs, etc) need to be added on separately. Shields/stripboard/breadboards/etc are all methods of creating quick and easy electrical connections from the Arduino to the aforementioned peripherals: wires, or even aluminum foil would work too.

In terms of 'powering' a project, you'll need to provide external power in some form - batteries being the most portable. The Arduino will take any power supply with an input voltage between ~7v to 20v, so 9v batteries are quite popular.

One of the key skills you will need in Arduino development is creating a circuit based on a schematic. In your linked tutorial, the 'mechanical' end is shown in the first diagram: all the necessary connections are shown, and it's up to you to figure out how you want to make them. Connecting things point-to-point with thin wire is usually the easiest, but can get confusing quickly.

#5

Arduino and power...

Individual pins on Arduino (and most microcontrollers) max out at about 40 milliamps (anLED typically takes 15-20 milliamps), and you can't run EVERY output pin at 40 milliamps, because the entire board output for all pins at one time has a limit, like 150 - 200 milliamps.

In short, the Arduino can run low power devices (LED, signal to the base of a transistor, signal to a logic chip or another microcontroller, etc.) but any device requiring more power requires a heftier power supply.

If you look up "Run a DC Motor with Arduino" projects, because Arduino can't pump out enough amps to run most motors, you will see they usually... Use the Arduino to send a low current signal to the base of a transistor. The VCC or power source for the collector of the transistor is a separate battery. So, the transistor turns on and the battery (6VDC, 9VDC, etc. - whatever voltage and current needed for the motor and that the transistor can handle) and the battery provides the 1/2 amp or 2 amps or whatever current is required.

I presently have two projects that use this concept.

  1. A Rover Robot. The Arduino and all the sensors are run off a small 6 volt battery. The four motors, that draw about 1 amp each (no way Arduino can handle 4 amps) when running are powered from a larger 12 volt battery (rated at 1,000 milliamp-hours). This larger current is regulated by a small motor controller. Arduino sends a (low-current) signal to a motor controller. The motor controller draws from the 12 volt battery to power the motors at the desired speed.

  2. I am building a "Perpetual Pendulum" that uses a hidden magnetic coil to provide just enough magnetic pull on the bottom of a pendulum to keep it oscillating for months. The coil, when energized for several milliseconds each swing, draws 4 amps from a 6 volt power supply, far exceeding the Arduino available amps. I have a seperate 6 volt battery and a solid-state relay. At the appropriate time, Arduino sends a (low-current) signal to a solid state relay. The relay energizes the coil and allows the 4 amps from the larger battery to power the coil.

Both of these projects are self-contained... meaning the separate power supplies, the Arduino and all the hardware are enclosed in the body of the device. You just run wires of the desired length to/from the components as you wish.

#6

This is making more sense to me now. To make sure I'm understanding correctly, the Arduino is a micro-controller which means its job is to do what the name suggests, control components. It isn't here to help with circuits and because of that you'd use something like a shield or breadboard to make the electrical connections. In the tutorial I linked to the wires were soldered together instead of using a breadboard. Instead of approaching it that way, with more complicated projects shields or breadboards might be used to keep organized (well, one of many reasons I'm sure). Is this somewhat correct? Let me know where my thinking is off. Thanks a lot for all of the help guys.

#7

and you can't run EVERY output pin at 40 milliamps,

You shouldn't run ANY pin at 40mA.

#8

Arduino is a board, convenient for learning/prototyping/research, that is based on a microcontroller chip such as Atmega328. It not only provides supporting circuitry like voltage regulation etc., it also breaks out the pins of the microcontroller into comfortable input/output slots into which you can insert jumper wires and connect to external stuff on a breadboard, and also the Arduino board provides on-board USB communication so you can program it with your computer (for which the Arduino IDE/software/"C-C++ language" is very convenient and user-friendly).

For me, the phases whether over time with my learning evolution or over the course of a single project are like this:

1) Prepare/Test a circuit idea by connecting stuff (LEDs, buttons, analog-to-digital-converters, sensors, etc.) on a breadboard and the Arduino board, and coding the Atmega chip using Arduino.

2) Subtract the Arduino board, and make a "standalone Arduino", i.e., an Atmega chip by itself without anything excessive, on a breadboard (like in the URL below), and connect your whole circuit (LEDs, buttons, sensors, etc.) on the breadboard to the Atmega chip, and add USB communication if you want. Arduino on breadboard tutorial: http://arduino.cc/en/Tutorial/ArduinoToBreadboard

3) Subtract the standalone Arduino, and once the circuit has been tested, solder the whole circuit using the chips and wires onto a stripboard/Veroboard, for compactness and durability.

4) Subtract the stripboard/Veroboard circuit, and prepare a schematic using software such as Eagle, generate Gerber files from it, and send them off to PCB manufacturer, and you can have a fully ready, compact and reliable circuit in the form of a PCB.

Any of the above four would be fully-functioning for whatever task one intends but differ in the final shape they take... To me, they are just different stages of prototyping and have different advantages/disadvantages.

#9