AVR-Chat

--- In AVR-Chat@yahoogroups.com, Ralph Hilton <ralph@r...> wrote:

> Connect a 10k resistor from the sensor output to the ADC input and 
10k from the ADC input
> to ground. that will halve the voltage on the ADC input pin. For 
safety I would add a
> protection diode from the ADC input to the +5 volt line.

...if you look at Atmel's Application Note #182 you can see that the 
built-in protection diodes of AVRs are able to handle currents up to 
1mA. If you limit the current from/to the pins with your external 
resistor to that (at max. input Voltage including some healthy safety 
margin), you won't need the extra diodes.

HTH,
Stefan