Standalone arduino project without USB communication

I finished my project with Arduino, and now i want to free arduino board to use it in another project. I've found this: http://arduino.cc/en/Main/Standalone#.UxRQtEW4C00 But i want to use serial connection, not USB. After googling a bit, i've found this: http://www.hobbytronics.co.uk/arduino-atmega328-hardcore Is this right thing? Only a few resistors and two transistors is all i need? I have BC547B transistors instead of BC548 is it ok? Or it have to be exactly BC548?

Sorry if i hit wrong section for this topic.

That is not reliable. You can buy a rs232-to-ttl-level-serial converter. http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=rs232+ttl+-usb+-wireless+-driver+-mini&LH_PrefLoc=2&rt=nc&LH_BIN=1

Get some Pro Minis. They're ideal for building final projects and only $3 each.

http://www.ebay.com/sch/i.html?_nkw=arduino+pro+mini

Arduino Uno sketches will run on them with no modification (it's the exact same chip!)

You'll also need one of these to program them:

http://www.ebay.com/sch/i.html?_nkw=usb+ftdi+arduino

I like the little red ones with the female connector - they just plug directly onto the end of a Pro Mini (after you solder the header onto the Pro Mini)

Since you don't have the right mix of transistors (NPN and PNP), get yourself a MAX232 and some 1uF caps:

http://www.digikey.com/product-search/en?FV=fff40027%2Cfff801a4%2C1140050&k=max232&mnonly=0&newproducts=0&ColumnSort=1000011&page=1&stock=1&pbfree=0&rohs=0&quantity=&ptm=0&fid=0&pageSize=25

Caltoa:
That is not reliable.
You can buy a rs232-to-ttl-level-serial converter.
http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=rs232+ttl+-usb+-wireless+-driver+-mini&LH_PrefLoc=2&rt=nc&LH_BIN=1

I would build something like this by myself rather than buying already made thing. Is this converter ok?

fungus:
You’ll also need one of these to program them:

http://www.ebay.com/sch/i.html?_nkw=usb+ftdi+arduino

I like the little red ones with the female connector - they just plug directly onto the end of a Pro Mini (after you solder the header onto the Pro Mini)

But it uses USB, i want to (and i have to) use normal rs232.

That's what I recommended, MAX232 and the 5 caps. See page 7 of the datasheet. Serial library only supports Rx, Tx, so connections to pins 2,3,5 are all that is needed.

If you are downloading sketches vs RS232, you will need to manually reset the promini when the IDE shows "Compiled xxx of 32xxx bytes". This can be easier to time if you open File:Preferences and enable verbose outputs.

ndd12: But it uses USB, i want to (and i have to) use normal rs232.

Ummm...so you don't need the little red board then. It's a USB to RS232 converter. Remove it and you just have RS232.

The point is this: Building your own Mega328 board is silly when you can get them pre-built on eBay for under $3.

A Pro Mini is an ATmega328P on a little PCB board with a 16MHz crystal and a voltage regulator. They have the exact same connections as an Arduino Uno(*), they're 100% software compatible with an Arduino Uno, they cost $3. With shipping. And header pins so you can stick them in breadboards.

(*) In fact they usually have two extra analog inputs - A6 and A7.

The RS-232 converters from Ebay and the schematic in the link use the MAX232 or MAX3232. You can buy it, or build it, it's all the same. http://en.wikipedia.org/wiki/MAX232

fungus: The point is this: Building your own Mega328 board is silly when you can get them pre-built on eBay for under $3.

Well... yes :grin: But, all needed parts to make own board i can get in next day, and for board from ebay i need to wait 2 or 3 weeks :P Anyway, its good idea, now ill make my own just to try and be proud of myself that i did something :grin:

Thanks all for replies, now i know what to do:)