Cheapest way to make multiple arduino devices?

Forum 2005-2010 (read only) General Frequently-Asked Questions
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Yes, no need to have the built up arduino if you are building the chip directly into a circuit.
Sure does make it convenient to be able to disconnect it from everything else tho when you run into programming difficulty.

  1. Will leave to others to answer, I have only used crystal equipped devices for solid comm's with other devices.

  2. Not 4 alkaline battery AAs - that would be 6V. The chip has absolute max operating voltage of 6v, but will probably be running pretty warm there and will likely shorten device life.
    4 NiCds maybe, ~4.8V. I have used 3 AAs just fine, was still going strong as voltage dropped down from 4.5 to 4.25, bypassing the regulator.
    I have a 8MHz Promini running off a 3.7v Li battery now, also bypassing the regulator.
    See section 28 of the ATMega datasheet.