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Support Forum » Pin Voltage and Reading the Data sheet

July 09, 2009
by sgmaniac1255
sgmaniac1255's Avatar

im working on my Tuner protect, and the thought crossed my mind.

"What Voltage do i need to make the Pin on the MCU read High?"

i looked in the Data sheet and found the Electrical Characteristics section with the table that has the info i wanted. but i hit a technical stumble block. the chart says 0.6Vcc min to be read High.

does this mean 0.6 Volts, or (0.6 * Vcc)?

PS. is there a data sheet for the Buzzer that came with the kit?

July 09, 2009
by mrobbins
(NerdKits Staff)

mrobbins's Avatar

Hi sgmaniac1255,

It means (0.6 * Vcc) or about 3 volts. If others are curious, I wanted to point out that you are referring to Table 28.2 on page 304 of the ATmega168 datasheet. To summarize, for a Vcc=5 volts as we have in the provided setup, the bit is read "0" if Vin < 1.5 volts, and the bit is read as "1" if Vin > 3.0 volts. The range in between those voltages, between 1.5 and 3.0 volts, is an undefined region (might be 0 or 1), and this allows for some manufacturing variation.

Sorry, I don't have any datasheet for the piezoelectric buzzer at this time.

Mike

July 09, 2009
by sgmaniac1255
sgmaniac1255's Avatar

thank you for the quick reply. that's what i thought, but wasn't sure... its kind of obvious now that you mention it.

thanks again

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