Mixing 5V Arduino Mega 2560 with 3.3V XBee Pro S3

Hey Everybody,

I am currently trying to interface an Arduino Mega 2650 with an XBee Pro S3 using serial communication.

I am also trying to interface a 4D Systems uLCD-70DT with an XBee Pro S3.

The Mega runs at 5V. The 4D Systems runs at 5V. The XBee runs at 3.3V.

My questions are as follows:

  1. Will the “SparkFun XBee Explorer Regulated” manage all of the level shifting for me? (SparkFun part number WRL-11373 or Parallax part number 32401)

OR

  1. Can I use the 3.3V output on the Mega to power the XBee? Or do I need a separate 3.3V regulated voltage to power the XBee?

  2. Do I need a voltage divider or voltage shifter to send and receive signals between the Mega and XBee? And between 4D Systems and XBee?

The XBee will send 3.3V signals to 5V Mega and the 5V 4D Systems. This is probably okay for serial communication.

But I am not sure whether or not I can send 5V signals from the Mega to the XBee or from the 4D Systems to the XBee. Will this damage the XBee (documented supply voltage is 3.0-3.6V).

TIA,

–Neal

Hello Neal.

Will the “SparkFun XBee Explorer Regulated” manage all of the level shifting for me?

Yes, the Explorer Regulated takes care of creating a 3.3 volt power supply for the XBee and level shifts the RX and TX lines.

Can I use the 3.3V output on the Mega to power the XBee? Or do I need a separate 3.3V regulated voltage to power the XBee?

I'd avoid that since the Explorer Regulated already takes care of creating a power supply for the XBee. Using the 3.3 volt pin on the Mega will just complicate things and create the potential for other issues.

Do I need a voltage divider or voltage shifter to send and receive signals between the Mega and XBee? And between 4D Systems and XBee?

No, the Explorer Regulated takes care of level shifting for you. It's important to remember though that you don't want to connect the XBee, Mega and your display all to the same RX/TX pins. The XBee should get it's own pair of serial pins and the display gets another. Communication between the XBee and display is done through the Mega.

But I am not sure whether or not I can send 5V signals from the Mega to the XBee or from the 4D Systems to the XBee. Will this damage the XBee (documented supply voltage is 3.0-3.6V).

The XBee itself will be damaged by 5 volt I/O so you can’t give it anything more than 3.3 volts. It’s kind of a moot point though since you’re using the Explorer which will take care of level shifting for you. Remember that the XBee Explorer Regulated only level shifts the RX and TX pins, if you use any of the XBee’s other GPIO pins, you will need to level shift those on your own.

TL;DR

Just use the XBee Explorer Regulated and make all your power and data connections between the Mega and XBee through that and you’re OK.

Dear Chris,

Thank you for the awesome reply. I purchased 2 of the SparkFun XBee Explorer Regulated modules. Thank you.

–Neal