Arduino Nano v3.3 interfacing to ESP8266 Wifi


I am interfacing a Nano v3 to an ESP8266 Wifi module (

The nano uses 5v logic, and the ESP8266 is all 3v.

I am using a regulator to get the 3v power from the 5v rail (which I understand can supply the 300mA needed). All that works fine.

My issue is that the communications seems to not "hook up" when using the hardware TX and RX pins in the arduino. The arduino TX led gets lighted up (continously - it doesn't stop) but the ESP8266 shows no activity.

After trying different things, I decided to try using the SoftwareSerial, using pins 10 and 11 as RX and TX. Puzzling enough that works (same logic level shifter, same power, same circuit in general).

I honestly don't know what to check. I'd like to use the hardware serial pins for obvious reasons (much more reliable in my opinion).

BTW: initially I was taking the TX of the ESP8266 and plugging it directly to the arduino (thus feeding a 3v line into a 5v). That works when using the SoftwareSerial. Eventually I tried the simple shifter below to feed 5v to the hardware RX in the arduino... still does't work.

So... I am looking for general orientation... I have already exhausted all my ideas to troubleshot this.


I don't know what causes your problems, but remember that there are disadvantages using the HW serial: Debugging printouts is less easy, and you will probably need to disconnect the Rx/Tx wires to the ESP when you want to upload new sketch to the Nano.

The main disadvantage with using SW serial could be that the speed is limited.