Own atmega2560 board

Hello! I have bought a smd adapter that accepts 100 pin AtMega2560 chip. I am going to make my own "arduino board", so I need some help. 1.) I think the mcu can be bought with bootloader programmed, is that so? 2.) If not, I think it's possible to program the mcu using my Mega 2560 board. There is an example using arduino uno as programmer on this site, and so Mega 2560 can do the job also? 3.) If I use Mini USB Adapter http://arduino.cc/en/Main/MiniUSB with my design, then I can use USB connection to my PC. If I don't use the USB adapter, then I think I can use normal RS232-connection to mcu, true?

I want to do all this because I haven't found an Arduino board with more that 2 Tn Counter/Timer clock inputs available. I need more than 2 in my application. thx

If I don’t use the USB adapter, then I think I can use normal RS232-connection to mcu, true?

“Normal” RS232-connection ?

You do mean using a MAX232 to interface the dangerous (to a MCU) RS-232 voltages, don’t you?

Thing is - the MAX232 modules on eBay cost if anything, more than the USB to TTL converters. Much the same on the more “reputable” sites. You need either one interface or the other.

1) SMD-chips rarely have a bootloader integrated if you buy 'm. Certainly with a 100-pin chip it's quite hard to write anything to the chip without soldering it first. 2.) Yes, no problem. With the sketch ARDUINOISP in the examples you can turn it into a programmer. If you read a bit on how to use it it's quite simple. 3) You can use a USB-adapterboard to connect your Mega2560 to your computer. RS-232 (like the comport on your PC) works with difference of voltage levels up to 25volts. Voltages on your arduinopins are TTL-based, 0 and 5 volt (or 0 and 3.3 volt if you power the board with 3.3v). Connecting your arduino directly may there for ruin Arduino/parts of your PC.

You can convert TTL-signals in RS-232 signals with an MAX232-chip, a few capacitors and make both compatible though. If you don't want to build it, you could also buy cheap modules like this to communicate using RS-232.

I'd suggest Nick Gammon's program to bootload a 2560: http://www.gammon.com.au/forum/?id=11635

I use this FTDI module for USB/TTL adapter: http://www.mouser.com/ProductDetail/mikroElektronika/MIKROE-483/?qs=%2fha2pyFadugsEwyLV5fFyIWdPbushEDhRSvnBE0ODG8%3d Connect +5, Gnd, Rx, Tx, DTR thru a 0.1uF cap to reset pin which has 10K pullup to +5.

Thanks a lot for everybody!!!
Paul: I have some Max232 left from my previous projects, hah. I made a ISA Z8S180 board and an I/O board for it (160*100mm both). Hard job it was, but works fine!!

Instead of soldering the chip by hand I would suggest you to buy a breakout board for your convenience. Some boards could be of use to you. http://doproto.com/store/16-serial-to-usb-rs232-and-ethernet

Regards Polash