Hello, I've been going through a lot of tutorials online on using an atmega8 for USB to TTL conversion instead of an FT232 which is a lot more expensive compared to just an atmega8 . I was looking at http://free-electronics-project.blogspot.com/2011/06/serial-to-usb-home-made-using-atmega8.html and http://makecircuits.com/blog/2009-03-23-usb-to-rs232-using-atmel-attiny2313-or-atmega8.html .. I guess both links are pretty much the same. I would like to know if its possible to use an atmega8 for USB to TTL conversion FOR an arduino to communicate to the PC i.e. basically use an atmega8 in place of the FT232 USB to TTL . will it be Arduino IDE compatible? Thanks..
Yes, as long as you have the ATMega8U2, which has the USB interface built in. Only available in 32 pin TQFP. Maybe get a TQFP to DIP adapter for easier prototyping.
2.2.7 DUSB Full Speed Negative Data Upstream Port 2.2.8 D+ USB Full Speed Positive Data Upstream Port 2.2.9 UGND USB Ground. 2.2.10 UVCC USB Pads Internal Regulator Input supply voltage. 2.2.11 UCAP USB Pads Internal Regulator Output supply voltage. Should be connected to an external capacitor (1?F).
"The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega8U2 programmed as a USB-to-serial converter."
There is another USB to serial converter - MCP2200, made by Microchip. It's the cheapest solution at the moment, around 2 bucks for single IC in SOIC(!) package. It's CDC ACM, like current Arduinos.