AVR

Extremely useful articles:
http://extremeelectronics.co.in/avr-tutorials/using-the-usart-of-avr-microcontrollers-reading-and-writing-data/
http://extremeelectronics.co.in/avr-tutorials/using-the-usart-of-avr-microcontrollers/

atmega168/328p: avrdude -c usbasp -p <MCU> -U lfuse:w:0xff:m -U hfuse:w:0xd7:m -U efuse:w:0x07:m -qq

FUSE:
-U lfuse:w:0xFF:m
tick EEPROM
untick BOOTRST, untick BOOTSZ*
untick all BODLEVEL

http://eleccelerator.com/fusecalc/fusecalc.php
http://www.martyncurrey.com/arduino-atmega-328p-fuse-settings/

http://www.appelsiini.net/2011/simple-usart-with-avr-libc

Read comments here: https://github.com/tuupola/avr_demo/blob/master/blog/simple_usart/Makefile