The question may seem oddly phrased, but bare with me..
I've been playing with arduino for the last month or so and I've learned a lot, enough to have come up with some projects of my own.
What I'm wondering now tho is how do I take what I've programmed, what I've built on my breadboard and move it ATMEGA and all to an actual prototype that I can put in a housing?
I guess my main question is, what is the base requirements to make it all work? Is something other then the ATMEGA required?
You can easily go from full-up Arduino to a reduced version, deleting un-needed components and adding any external parts used, special connectors, size/shape for planned enclosure, etc. by hiring somene like me to make your PCB, and build/populate it if you don't have the skills for that.
You can see examples of some of my designs here
If you just want to build a bare-bones version, then putting a Promini in your project is another simple way to go if you don't need much else.
I appreciate the suggestion but I'd much rather do it all myself
I'm still not sure what the minimum required hardware is tho..
Atmega, 16 MHz xtal with two 22pF caps (or a resonator), 10k reset pullup resistor, 0.1uF caps on VCC, AVCC, Aref, and 0.1uF cap from DTR from USB/Serial if you use that.
Here's a crude schematic showing Serial header and ICSP header as well.
Diode across reset resistor keeps any spikes from fooling part into going into high voltage programming mode & looking hung.
Wow thanks, that looks a bit daunting tho!
How small could that be? I was hoping to put it in a box with these dimensions: 82x51x32 mm.
That all feels like it would be bigger..
Not much bigger than the size of the chip.
You can see the chip, crystal caps, etc, here.
Chip is 1.4" x 0.3", so 1.4" x 0.6" to hold it all. Maybe 35mm x 35mm? Definitely fits in 50mm x 50mm.
If you want it really small, can even mount it all on top of the chip: You searched for ardweeny - Solarbotics Ltd.
Is everything on that picture required or is it just as a reference?
There are some really tiny and inexpensive clones available which are much smaller and cheaper than the official Arduinos so much more suitable to be embedded in a permanent project. If you need hardware additional to the basic Arduino then you may be able to find a clone that includes it - for example there are clones with motor drivers, network interfaces, RF transceivers, battery chargers, various sensor modules, SD cards etc.
Clones are often available with header pins/sockets installed, or without headers, so you can decide whether you want to use permanent soldered connections or a plug-in system. If you want to include a DIY circuit in your solution you could implement that on a piece of prototyping board, or use a clone which includes a prototyping area.
If you can't find a clone that fits what you want perfectly, then some fab houses publish a catalog of third party board designs which you can get from them for the manufacturing cost plus a commission to the original designer. (If you design your own board, you would have the option to offer it for sale on the same basis.)
If you choose a clone without a USB socket then you would need to provide some other way to program it - for example using a FTDI interface or via the ICSP header.
My board is just a reference - the needed components from the schematic are at the lower left - xtal + 22pF caps, 0.1uF caps, and resistor above the uC chip.
Add headers as you need for you project.
Thanks for the help! I've actually found some guides now so come next payday I'll try on the breadboard to make everything work!
I've been reading this topic with great interest. I have now made 2 prototypes (solderable boards), one with the ATMEGA328 chip itself and the mentioned components, and the other with a ProMini from SparkFun - I set up this one to be programmed with mini USB.
Thanks for the schematic Crossroads!
I do have a simple question that I have been unable to find an answer to:
Just exactly why is a 0.1uF cap needed in series between the USB or FTDI RTS pin and the chip RESET pin? If I don't put this in there, it will not auto-reset of course.
Well, I did find this, but it's over my poor head
The cap lets AC signals only thru. When the outer side is not connected to anything or is high, the inner side sits at 5V due to the 10K reset pullup resistor.
When the outer side goes low, the inner side goes low from the changing signal, then the 10K resistor pulls it back high again. When the outside goes high again, the inside is already high so nothing happens.
The time it takes to go from low to high is determined by the cap value and the resistor value.