protect arduino pins from high and negative voltages

[xi-boy]

i am building a arduino based device wich is powered by one single 9 volt batterie.
it receives analog and gate signals with its on board analog/digital convertors and digital pins and outputs signals via one mcp4921 dac and on board digital pins.
i want to buffer, protect and maybe scale signals of the dac and adc with LM358 single supply opamps.
i could find plenty of examples for audio modules with +/- supply's
and how to protect microcontroller inputs from negative and to high voltages but nothing for single supply devices.

thanks in advance for any help and hints

[bubzy]

why are you feeding negative voltages into a circuit running off a single sided supply?

have a look at this
http://www.national.com/an/AN/AN-31.pdf
theres one called offset voltage adjustment for voltage followers, im pretty sure that if you connect the pot to +v and 0v that you can use it with a single sided supply no problem, note the equation at the bottom, if you change resistors around you can get the circuit to "step down" the voltage.

dont take my word for it though i could quite easily be wrong(its happened once before), read up and check it out.

-bubzy

[xi-boy]