Hello, i just put my atmega328-pu with an arduino bootloader on a breadboard. I connected it based on the examples given here on arduino's site, and i am using an UART device for the serial communication. The chip is running blink example. How to upload the chip because i get the following message:

avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51


A little more information would be helpful.

Either your bootloader did not take (No blink from D13/PB5 when powered) or communication issues with the USB/TTL device (reset cap not installed). Both of those will produce your error and vastly different solutions.