Breadboard Arduino 3.3V @ 8 MHz

NOTE: I’m trying to get a 3.3V 8MHz Arduino working on a breadboard. I can make it work fine at 16 MHz but cannot get it working at 8 MHz. I am documenting the current status here while I get some help and plan to update this page once I have it working.

First, we’ll follow the stock instructions for setting up a regular (5 V 16 MHz) Arduino a breadboard, so wire up the breadboard using these instructions: http://arduino.cc/en/Main/Standalone

Be sure to set the AVR Pocket Programmer to “No Power” and make sure that the circuit board is powered with 3.3 volts (I used an LD33V regulator and a 9V battery).

With the AVR Pocket Programmer connected, use avrdude from the command line to verify that the circuit is wired correctly. You should see output like this:

$ avrdude -c usbtiny -p atmega328p

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.00s

avrdude: Device signature = 0x1e950f

avrdude: safemode: Fuses OK (H:05, E:DA, L:FF)

avrdude done. Thank you.

Arduino IDE 1.6.2

Board -> Arduini Pro or Pro Mini

Processor -> ATMega328P (5V / 16 MHz)

Programmer -> USBtinyISP

Tools -> Burn bootloader

Now connect USB to FTDI Basic

Programmer -> AVRISP mkII

Port -> dev/cu/usbserial-AL00ERTT (or similar)

Upload sketch

Serial monitor should show “Hello”.

Now to get the same thing working at 8MHz…

In Arduino IDE I chose the 3.3 V / 8 MHz processor option and uploaded the new bootloader using the same technique as before. After doing this I am unable to upload sketches.

After much hair-pulling, I think I at least see the issue now. Changing to 16 MHz did not change the fuse bits, so I am assuming that the Pro Mini uses an external 8 MHz oscillator, whereas I still have a 16 MHz oscillator.

I have two choices now – figure out how to set the fuse bits for the internal 8 MHz oscillator or buy an 8 MHz crystal oscillator.

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