Arduino Uno Voltage of Logic 1 from output pins?

Hello,

I was wondering what the exact voltage of the Logic from the output pins is? Is it actually close to 5V? I've used a few other 5V microcontrollers before and the logic 1 outputs were usually in the 3.5-4V range.

jumpingJacks105:
Hello,

I was wondering what the exact voltage of the Logic from the output pins is? Is it actually close to 5V? I’ve used a few other 5V microcontrollers before and the logic 1 outputs were usually in the 3.5-4V range.

It depends on how much current is being drawn from the output pin, as more current drawn will gradually lower the output pin voltage. It’s all in the chip’s Atmel datasheet. Otherwise you can just assume that the output pin voltage will be close to whatever the Vcc voltage is that is powering the chip.

Lefty

jumpingJacks105: I've used a few other 5V microcontrollers before and the logic 1 outputs were usually in the 3.5-4V range.

Ouch! You may want to reduce the current flow. The chart stops at 20ma @ 4.4 volts. At 3.5 volts you are probably exceeding the absolute maximum rating of 40ma.

See section [u]28.1 Absolute Maximum Ratings[/u] and [u]Figure 29-306.ATmega328: I/O Pin Output Voltage vs. Source Current (VCC = 5 V)[/u] in the datasheet.