guidance for optiboot install on proMini using another proMini

Other Hardware 3rd Party Boards
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You should totally check out MiniCore, which lets you use different clock frequencies as well. Atleast I prefer to select what kind of microcontroller I'm using rather than the board. The UNO and the Pro mini got identical microcontrollers, but different boards.

  1. Have a look at this setup. The setup are using an Arduino Uno, but it will be the same pins for the pro mini as well

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  2. first upload the "Arduino as ISP" sketch on the pro mini that's going to boatload the other microcontroller.
    If you decide to use MiniCore, you choose "ATmega328p" and "16MHz" from the boards menu, and select "Arduino as ISP" as the programmer tool. Note that "Arduino as ISP" and "ArduinoISP" is NOT the same!
    Then you hit "Burn bootloader". If no error message is present, and the onboard LED is flashing twice every seconds, that means you've succeeded :slight_smile: