Arduino Mega 2560 as usb serial adapter

Projects Interfacing w/ Software on the Computer
1

Hi, I have two questions, one is relatively shorter so i post both
I was trying to communicate with an old nokia phone ( nokia6220 ). As far as I know that device uses 3.3v serial TTL logic. I am trying to connect that device to my PC. I lost its PC cable (which was DKU-5) and since the phone is almost ancient I cannot find another pc cable in my local electronics stores.

So I made some research on internet and happened to find arduino boards has usb-serial converters and it can be utilized as such. For instance : Use the Arduino Duemilanove as a serial adaptor - .[ZooBaB].

But these tutorials are for older versions of arduino boards. I have Arduino Mega 2560 which does not have FTDI chip. As far as I understood from this tutorials main mcu in the board is by-passed and only FTDI chip is used. However in arduino mega 2560 the main mcu does usb/serial conversion (?)

So is this method (connecting RESET and GND etc.) is applicable to AtMega16u2 based boards? If not what is the new method?

Here is another thing , I tried to build some external cricuitry to convert serial TTLs voltage levels to 0-5V. Is there an easy way of this. i.e. can I talk arduino with directly 3.3v logic?

2

Yes. The Atmega16U2 can be used as US/Serial adapter by connecting Reset on the power header to Gnd.
74HC4050 is used as a voltage level translator from 5V to 3.3V.

3

If all you need is USB to TTL you could use an FTDI cable (also called USB-TTL cable) - many of them support 3.3v and 5v.

...R