Optiboot

Guide for AVRDragon, atmega328p, and optiboot bootloader.

gotchas:

• wrong atmega328 (need atmega328p-pu, not atmega328-pu) (though this can still be used)
• need fuse bits set separate from programming hex (pickit w/pics on the other hand handle this all in one)
• need lock bits set
• need 16MHz crystal when programming hex and lock bits (can use one from uno board)

quick guide:

set proper wiring on avr dragon (see image in pics) set fuse bits

avrdude -b 19200 -c dragon_isp -p m328p -v -e -U efuse:w:0xFD:m -U hfuse:w:0xDE:m -U lfuse:w:0xFF:m

add crystal (pins 9 and 10 on atmega328p, see datasheet) , load hex, and program lock fuse

avrdude -b 19200 -c dragon_isp -p m328p -v -e -U flash:w:hexfilename.hex -U lock:w:0x0F:m

hexfilename.hex - the optiboot loader is included in e.g.

arduino-1.8.5/hardware/arduino/avr/bootloaders/optiboot_atmega328.hex

tips/troubleshooting

• use another Uno's crystal if you don't have one on hand. Solder wires and jump to dragon ziff socket.

References

• https://forum.arduino.cc/index.php?topic=125622.0 - where is optiboot hex file in arduino download folder
• https://learn.sparkfun.com/tutorials/installing-an-arduino-bootloader - fuse and lock bit information (seems to be incorrect)
• http://www.martyncurrey.com/arduino-atmega-328p-fuse-settings/ - general info on atmega328p fuse settings.