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Is it possible to take a bare ATmega328 chip, and with an Arduino as ISP, burn a sketch directly to the chip (e.g. not needing a bootloader), or is the bootloader required to run Arduino sketches? I want to embed the ATmega328 into a different device, and do not want the overhead of the entire Arduino board.

I have looked at https://www.arduino.cc/en/Tutorial/ArduinoToBreadboard and https://www.arduino.cc/en/Tutorial/ArduinoISP, and want to do the "minimal circuit" approach (as my application does not require 16MHz).

The tutorial described has steps to first burn a bootloader, then remove the chip from the Arduino, and then install the sketch. Ideally, I would like to skip the bootloader and removing the chip from my Arduino. Ideally, I would like to do it all from Arduino Studio (not AVRDUDE CLI).

I don't mind "dedicating" my Arduino to this (as I assume it's just burning the ArduinoISP sketch whenever I want to burn to a new ATMega328).

Thanks

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2 Answers 2

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It is possible to skip the Burn Bootloader step. When you do Upload Using Programmer the bootloader is overwritten and thus serves no purpose. However, there is another reason for the Burn Bootloader step, to set the correct fuses for your board selection. The fuse settings configure things on the ATmega328 such as clock speed and clock source. If the ATmega328 you are using doesn't happen to have the correct fuse settings for the board selection you're using in the IDE then things may not work or may not work correctly. For this reason it's best to always do the Burn Bootloader step the first time you use the ATmega328 and any time you change the board selection or other settings related to that board selection(such as custom Tools menu settings). Since you're not using an external clock source for your ATmega328 make sure that you don't select a board that is configured for an external clock as this will cause the chip to no longer work until you have connected an external clock.

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  • Thanks for the detailed response. I assume if I get the clock speed wrong, I can't even burn the bootloader / anything to it? The chip I currently have has been programmed for a 14.3mhz (give or take?) external crystal, which I was not planning on using in the circuit. Will that be an issue?
    – AndrewP
    Oct 6, 2016 at 4:08
  • @AndrewP: The clock rate only affects the delay and timing routines; ISP doesn't care about the exact speed provided certain minimums (detailed in the datasheet) are met.
    – Ignacio Vazquez-Abrams
    Oct 6, 2016 at 4:14
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The bootloader only enables serial programming of the device; it is perfectly possible to run Arduino programs without it provided that the code is compiled with the same hardware options (MCU model, clock speed, etc.) that the standalone device/board uses.

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