Is it possible to connect the XBee to the Arduino without a shield? Currently most of the sources that I have looked at have some sort of shield connected.

I use this shield currently: http://www.adafruit.com/products/126.

From the looks of it, the shield only ensures that the power levels are regulated to 3.3v from the 5v output that the Arduino gives. Can I then just build a small regulator circuit rather than purchase the entire shield for $10 + shipping?

  • \$\begingroup\$ Yes. You can do it, but I'd also say that $10 is a bargain. Saves you the headaches with building something custom. \$\endgroup\$ – Gustavo Litovsky Feb 18 '13 at 19:40

Yes, all you need to do is logic level conversion.

Adafruit does that by using 74HC125 buffer:

enter image description here

You can set up the same schematics on your breadboard or use it in your custom design. If you have Arduino Uno rev3, you can skip +3.3V regulator as Arduino provides a capable +3.3V regulator on board.

The schematics picure is from Adafruit page.

  • \$\begingroup\$ No, using the onboard 3.3v will draw too much power, and fry it. The Arduino 3.3v regulator is relatively weak/small, and not suited to dissipate too much heat. \$\endgroup\$ – Passerby Feb 18 '13 at 20:26
  • \$\begingroup\$ @Passerby how much can it handle with 5V input? \$\endgroup\$ – Kortuk Feb 18 '13 at 20:46
  • \$\begingroup\$ @Passerby Arduino Uno uses LP2985 Micropower 150 mA Low-Noise Ultra Low-Dropout Regulator which features Overtemperature/overcurrent protection. Random XBee-PRO® ZB SMT draws 114 mA @ 3.3 VDC max in transmit mode. Onboard regulator will provide enough current and will not fry in case of overcurrent. \$\endgroup\$ – miceuz Feb 18 '13 at 21:39
  • \$\begingroup\$ @miceuz only the Rev 3 Uno has that regulator. You also have to account for heat, and the level shifter, the leds. If they have a rev 2 or 1 Uno, or a different Arduino that has the ftdi chip, it only provides 50ma. \$\endgroup\$ – Passerby Feb 18 '13 at 21:45
  • \$\begingroup\$ @Passerby good to know. Updated my answer accordingly. \$\endgroup\$ – miceuz Feb 18 '13 at 21:47

Just as a note, the adaptor you talk about isn't an Arduino Shield. From the LadyAda Wiki:

Specifically created for use with an FTDI cable to connect to a computer via USB. This means that you can use, configure or upgrade the adapter painlessly simply by plugging in a cable

It was meant for computer usb-to-serial cable use.

And you should not skip the 3.3v regulator from the 5v output. The onboard arduino 3.3v regulator can only handle about 50ma, at 12v input. Too much heat from regulation will kill it at the current needed by the XBee. This is why most if not all XBee arduino shields have a 3.3v regulator, instead of tapping the Arduino's 3.3v line.

  • \$\begingroup\$ What current can it handle with 5V input? \$\endgroup\$ – Kortuk Feb 18 '13 at 20:47

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