guidance for optiboot install on proMini using another proMini

Using Arduino Microcontrollers
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Hi!
I try to install optiboot bootloader to an arduino pro mini (5V 16Mhz) using another pro Mini as ISP programmer.
I rely on the idea of this clip:
What i do until now:

  • installed optiboot into arduino pro mini
  • i create in boards.txt (optiboot folder) entry for my Pro Mini and named "[Optiboot] Arduino Pro Mini 5V 16Mhz w/ ATmega328"
##############################################################

atmega328o.name=[Optiboot] Arduino Pro Mini 5V 16Mhz w/ ATmega328
atmega328o.upload.protocol=arduino
atmega328o.upload.maximum_size=32256
atmega328o.upload.speed=115200
atmega328o.bootloader.low_fuses=0xff
atmega328o.bootloader.high_fuses=0xde
atmega328o.bootloader.extended_fuses=0x05
atmega328o.bootloader.path=optiboot
atmega328o.bootloader.file=optiboot_atmega328.hex
atmega328o.bootloader.unlock_bits=0x3F
atmega328o.bootloader.lock_bits=0x0F
atmega328o.build.mcu=atmega328p
atmega328o.build.f_cpu=16000000L
atmega328o.build.core=arduino:arduino
atmega328o.build.variant=arduino:standard

Next steps:

  1. wiring. Here i have an difficulty about pin D10 (SS) and RESET. How to connect correctly from ISP arduino to target arduino. From clip i understand that need to connect D10 (arduino ISP) to RESET pin on target pro Mini.

  2. how to burn bootloader? I know that first need to install ArduinoISP sketch on arduino as ISP. After that i can try to burn bootloader. At this phase, what select as board? Is entry created before?

Thanks!

2

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:

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So my first doubt is solved. D10 pin (SS) from isp go to RESET pin on target.
About MCUdude. Is an interesting option. At least for two extra pins.

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