Xbee digital Input/Output voltage

Projects Networking, Protocols, and Devices
1

I was looking at the Xbee 1mW datasheet and saw that there was no maximum voltage for digital Input.

I think some people supply xbee with 3.3V and interface RX/TX pin with a 5V microcontoller without any interface.

Is this safe?

Datasheet
http://ftp1.digi.com/support/documentation/90000982_H.pdf
Look at page 10

2

johnyboy:
I think some people supply xbee with 3.3V and interface RX/TX pin with a 5V microcontoller without any interface.

They do, but they shouldn't.

Is this safe?

Not according to the manufacturer:
http://www.digi.com/support/kbase/kbaseresultdetl?id=2160

3

Hello, maybe the same sort of question, but do we just need a resistor to connect digital output from arduino to digital input from xbee ?
It's to use a PWM TLC5940 (or PWM Shield) with a xbee without a arduino.

Example :

  • At one side : Arduino digital output pin 9 and 10 to xbee DI input 0 and 1.
  • at the other side : xbee DI output 0 et 1 to TLC5940.

then control the TLC5940 wirelessly and with only one arduino.

So to connect the 5V digital output from arduino, to 3,3V DI input from Xbee ? what issues? Just resistor or regulator 3,3V?

Thanks a lot

4

I'm not really familiar with the TLC5940, but a quick spin through the datasheet indicates that it uses an SPI (or SPI-like) interface. Maybe someone more knowledgeable can chime in on that. But, if that's the case, that is not a protocol that can be sent directly through a pair of XBees.

siroptinmar:
So to connect the 5V digital output from arduino, to 3,3V DI input from Xbee ? what issues? Just resistor or regulator 3,3V?

Neither is optimal. Use a proper level-shifting circuit. I'd be surprised if a regulator would work at all, they aren't intended to be used to shift signal levels.

My favorite cheap-o level shifter is below, I've had good luck with it. A 74AHC125 buffer also makes a good level shifter.

xbee.png
xbee.png917×431 5.96 KB

5

Hi thanks,

About SPI :

There is a library for arduino "tlc5940" and "This library uses the PWM output ability of digital pins 3, 9, 10, and 11."

So maybe you're right , no possibility to send 4 PWM on Xbee?

Someone talk about wire and I2C to drive tlc5940, and it is possible to use it with Xbee, right?

Ciao

6

siroptinmar:
Hi thanks,

About SPI :

There is a library for arduino "tlc5940" and "This library uses the PWM output ability of digital pins 3, 9, 10, and 11."

So maybe you're right , no possibility to send 4 PWM on Xbee?

Someone talk about wire and I2C to drive tlc5940, and it is possible to use it with Xbee, right?

Ciao

Like I said, I'm really not familiar with the TLC5940, and certainly not with the library. As far as I know, the S1 and S2 XBees only do asynchronous (RS232-style) serial interface at a 3.3V level, not I2C, not SPI, not anything else that I am aware.