USB (simple) Serial Communication

This has probably been posted a few times, but I couldn't find anything helpful.

So I want to make a simple device that sends a serial message to my computer via USB, and so I want to buy an ATMega 168 (or something smaller, whatever will do the job), load the Arduino environment onto it. My plan currently is to buy an FTDI chip and pretty much copy the circuit on the Arduino Duemillanove. Now what I'm wondering is what pins I need to use. From what I observed, I only need the RXD and TXD pins. Is that true? Are all the other pins just... there?

Thank you for your time.

Or someone will finally use the v-usb, avr, software only usb implementation, make use of it with arduino and post the results here, for all inquiring minds to use. Link to the v-usb: http://www.obdev.at/products/vusb/index.html

You pretty much just have to use the TxD and RxD pins (and ground of course)! All the other pins are available for things like flow control but are not absolutely necessary.

You should copy the circuit from the Arduino schematic fairly closely and/or read the FT232 application notes in the device's datasheet as they have some important recommendations on decoupling capacitors and the like.

You also need the DTR line to act as an auto reset when the driver is enabled on the host side. (if you want that function)

Thanks for you quick and helpful replies.

Now I am interested in V-USB. Can this be integrated with the arduino environment? If not, where could I learn? I have little to no experience with working with microcontrollers outside of Arduino. I would appreciate it if someone could point me to a tutorial or something.

EDIT: Also, what does a chip require to make it an "Arduino"? From the looks of it, it looks like it's only required to have a clock on it, but also filling in essential components like reset.

Now I am interested in V-USB. Can this be integrated with the arduino environment? If not, where could I learn? I have little to no experience with working with microcontrollers outside of Arduino. I would appreciate it if someone could point me to a tutorial or something.

V-USB was formerly known as AVRUSB: http://code.rancidbacon.com/LearningAboutArduinoAVRUSB.

--Phil.

what does a chip require to make it an "Arduino"?

It is the boot loader that makes it an Arduino. This needs to be flashed onto a raw chip. For the official explanation of what makes an Arduino see:- http://arduino.cc/en/Main/Policy