Arduino; burning the bootloader

I bought some ATmega328, not 328P, for a new project. I think the trouble started here. There are lots of pages in Internet explain how to burn the boorloader onto a microcontroller using Arduino board. I followed those instructions and successfully burned the bootloader but I was confused by those instructions at the same time. So here is yet another instructions.

• ATmega328 (not 328P) without bootloader
• Arduino Uno
• Arduino Leonardo (as ISP)

Wiring

Use jumper wires to connect two boards.

Leonardo	-	Uno
10	-	Reset
11	-	11
12	-	12
13	-	13

Use Arduino as ISP

I used Arduino IDE 1.6.8 on a Linux box. It is the latest version (Mar/2016).

1. Open a sketch
   File menu -> Examples -> 11.ArduinoISP -> ArduinoISP
2. Select a board
   Tools menu -> Board -> Arduino Leonardo
3. Select a port
   Tools menu -> Port -> /dev/ttyACM0 (Arduino Leonardo)

Because I did not use ISP connector (2x3 pins), I uncommented the following line (line 81) in the source code.

#define USE_OLD_STYLE_WIRING

Then click Upload button to upload the sketch to Leonardo.

Burn the bootloader

I had to edit boards.txt (arduino-1.6.8/hardware/arduino/avr/boards.txt) to  burn the bootloader and to build/upload a sketch later. I modified "Arduino/Genuino Uno" entry to support both 328P and 328.

1. Comment out the line.
   # uno.build.mcu=atmega328p
2. Add the following lines.
   uno.menu.cpu.atmega328p=ATmega328P
   uno.menu.cpu.atmega328p.build.mcu=atmega328p
   uno.menu.cpu.atmega328=ATmega328
   uno.menu.cpu.atmega328.build.mcu=atmega328

Then you will see new menu item if you select "Arduino/Genuino Uno". (If IDE is running, quit and run again to take effect.)

1. Select a board
   Tools -> Board -> Arduino/Genuino Uno
2. Select a processor
   Tools -> Processor -> ATmega328
3. Select a port
   Tools -> /dev/ttyACM0 (Arduino Leonardo)
4. Select a programmer
   Tools -> Programmer -> "Arduino as ISP"
5. Burn
   Tools -> Burn Bootloader

Upload a sketch

Somehow if you select Processor: "ATmega328" and upload a sketch, it failed.
avrdude: Device signature = 0x1e950f
avrdude: Expected signature for ATmega328 is 1E 95 14
         Double check chip, or use -F to override this check.

It said device signature was wrong. 0x1e950f is 328P's device signature and as message said 0x1e9514 is 328's device signature. I was confused but I just tried to build/upload with "ATmega328p", and it succeeded. A sample sketch worked okay too.

This is one thing I still cannot understand. Optiboot overwrites device signature? But anyway I can now upload a sketch to ATmega328 using Uno board and it is ready for a new project.

Appendix) Failed attempt

At first, I used a breadboard instead of Uno. And selected "Arduino Duemilanova or Diecimila" board when burning a bootloader. But it failed because of device signature mismatch.
avrdude: Device signature = 0x1e9514
avrdude: Expected signature for ATmega328P is 1E 95 0F
         Double check chip, or use -F to override this check.

In boards.txt, build.mcu is defined as below.
diecimila.menu.cpu.atmega328.build.mcu=atmega328p

I guessed it was the cause and removed 'p'.
diecimila.menu.cpu.atmega328.build.mcu=atmega328

Then it successfully burned and 13pin/led started blinking. I removed the ATmega328 from a breadboard, placed it on Uno board and uploaded a sketch. But I got the following error.
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00

I checked boards.txt again and I thought it was because Uno's build.mcu was ATmega328P. And so removed 'p' again.
#uno.build.mcu=atmega328p
uno.build.mcu.atmega328

But I still got the same error.

I was about to give up and I almost ordered new ATmega328P, but I found the way to burn ATmega328 using Uno board. I have to lean some more basics of a microcontroller, a bootloader and a board...