Hi, I'm new to arduino, so this might be a dumb question but...
I made my first arduino device, and wrote the program. It's very simple, it has 4 buttons, and when it reads the button input, it sends data through a serial port/USB.
Assuming I want to make three more devices that do exactly the same thing with the exact same code, do I really need three more arduinos? Or can I get three "somethings" and plug 3 chips into them that have the arduino code, and a USB port, and power...or...
So, yes and no. You can get three more Arduino boards of a smaller size (Nano, or ProMini). You can get an Arduino-compatible clone like the Bare-Bones-Board (BBB, http://moderndevice.com/) which is less expensive depending on if you get your own components or get it kitted.
You can also just get your own ATmega chips with some decoupling caps and wire it up yourself. You can either burn the bootloader and use an FTDI cable, or burn the HEX code with a ICSP.
For only a few copies of the same design, I'd second using the BBB (Bare Bones Board) or get a protoboard (PCB like board with 0.1" spaced holes) and implement an arduino clone on that (doesn't take up much room at all) and put the rest of your circuit on it. The easiest way to program it is to probably use your current arduino and put pre-bootloaded chips in the socket, program them, and remove them.
Moderndevice's Bare Bones Board (need a USB programming adapter/cable or similar interface, I use the FDTI cable) Modern Device
I just realized in your post you use the USB port as a serial connection to the PC, so the BBB is probably not the best option.
Check the next link for a possible answer to this problem:
This breakout board would interface nicely with either the BBB or my breadboarded design (use male header) to allow a USB serial port to the computer. The cable hanging off the breadboard is the same sort of thing but its a cable.
I assume your design is relatively simple, so that is why I chose the response I did. Hope this helps. I'll reply with my protoboarded arduino when and if I do it. It's been done before anyways.
The distributors get to do things in volume which helps their pricing a lot. On the one hand, you should only have to buy one USB breakout, don't know how much that helps the math.
For custom PCB you'd need to lay out your own PCB fab with Eagle or another layout package and get it fabricated somewhere. This layout prevents you from having to wire everything up by breadboard, everything's soldered in. If you're looking at making things in the 100's this is definitely the way to go if for no other reason than reliability and consistency.
If you wanted to make 100 of these, you would definitely need to design a custom PCB, and you can take many design cues from the original arduino board. I personally have not done that yet, I'm sure I'll find a reason to in the future. It's a bit involved, and someone else might be able to help. There are tutorials everywhere too.
You can get a USB enabled Freeduino for $20 or so, so that might be a better option. You can add one of those protoboards for your other bits.
mdowning, I think the main function of his design is based around using the USB port as a serial port to the computer, so I think he needs a breakout board for every one of them. I may be wrong.
EDIT:
I took this picture of some of the crap I have to give you ideas:
Yellow = Cost Prohibitive, yet beautiful Arduino Nano solution
Red = DC Boarduino, mounts directly into breadboards and protoboards. (so does the nano, obviously)
Green = BBB, use male and female headers or solder directly to protoboard with male headers.
Blue = Custom breadboarded Arduino. Note the diode and resistor near the FTDI header don't do anything, they were going to get lost on my workspace so I put them there.
Ooohh cool, I see. So basically the boardino puts me in a position where I can eliminate one of my cable runs? instead of button to breadboard to arduino, i can just go button to breadboard, which is direct connected to the boarduino? That's clever!
I think the cheapest solution that still provides USB connectivity is something like a "Really Bare Bones Board" (or maybe a partially populated "single sided serial board" plus a cheap TTL-level serial USB/Cellphone cable, as described here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1237497869
Wow, West, you are everwhere, I think you answered my other question in another forum (Might've been over at processing...), thanks. I'll respond to this over in that thread, but I wanted to thank you here, in case you don't re read over there.
This might seem like an obvious question, but the 4-button -> Serial project was my very first Arduino task, so this is all very new to me.
Where, exactly, would I solder this cable to my board? Do I find the leads/cable pins (as described by Matt Elias, rx,tx,"common",red) and solder them to the RBBB's corresponding pins?
If so, what is the "common" or yellow wire? And where would I solder the red one?
The six holes along the left end of the board in the picture you posted are for a header to plug the cable into. The black wire connects to the one marked "G" (lower left corner of the picture). If you don't get a cable with the connector installed, you can solder the wires directly to the board. The order is black, brown, red, orange, yellow, green. Also, the cables come in 3.3v and 5v versions. Make sure you get the 5v if you want it to power the board.
