What is the voltage at the RX pin of the Arduino Nano?

Development Tools IDE 1.x
1

Hi,

I want to connect an ESP8266 to an Arduino Nano 3.0 but i am wondering what is the voltage at the RX pin of the Nano:

  1. when data is NOT being transferred from the ESP
  2. when data is being transferred from the ESP at 3.3V logic level voltage?
2

5v, from the tx pin of the attached serial adapter.

Esp8266 pins are 5v tolerant (per Espressif posts and tests by users - theres a nice writeup of a guy who verified that there is no excessive current when a pin is connected to 5v) - this wasnt widely known until recently due to the shoddy documentation for the esp8266.

There is generally a resistor in series with that pin, so when its directly connected to something else, that will be able to overpower the setial interface chip.