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I am using the IO pass through mode on an XBEE, so basically if one XBEE has a high input, it passes that input to the other XBEE and that XBEE's output is also high. Since the Raspberry pi has an output GPIO voltage of 3.3 and the XBEE takes in 3.3 volts in digital in, can I just pass the output of a RASPBERRYPI GPIO pin to the input of a XBEE pin?

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    \$\begingroup\$ Are you intending to send continuous data or short bursts of several bytes? I'm raising a few questions in the hope that they might get answered because they are relevant to the question. If in pass-thru mode, do you need to transmit a "throw-away" preamble in order to get the receiving XBEE locked in to the incoming RF signal? How long does this preamble need to be? Are you sending one-way data? Do you need to check for acknowledgements from the remote end's MCU? \$\endgroup\$
    – Andy aka
    Apr 8, 2013 at 19:15
  • \$\begingroup\$ It's continuous. Basically all it is doing is remotely controlling a relay. You don't have to worry about acknowledgment and all that jazz. I just basically want to make sure that I can hook the Raspberry PI to the XBEE input IO pin without a resistor without damaging either device. \$\endgroup\$
    – Ryan F
    Apr 8, 2013 at 19:35

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Yes you can and I'm assuming that they are both using the same supply power or if not they are, within reason, both at 3.3V with common 0V line.

As a matter of interest on my part, what are you doing to ensure random spectral noise doesn't cause a "relay activate" command.

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  • \$\begingroup\$ I am not doing anything. I didn't even consider that. I am just going off whether the Raspberry Pi is outputting high or low. Is that bad? The relay is triggered at 2.5 volts. \$\endgroup\$
    – Ryan F
    Apr 8, 2013 at 21:14
  • \$\begingroup\$ @RyanF I'm no expert on XBEE and if it is working for you then that is fine. Maybe just check to see what the XBEE spec says about stuff when you are not transmitting stuff because you presumably don't want the relay to turn on with static noise in the airwaves. If it were a plain ordinary RF transmitter and receiver with data slicer you'd have to avoid this problematic scenario by transmitting a codeword but even that isn't safe enough against some interference. \$\endgroup\$
    – Andy aka
    Apr 8, 2013 at 21:19

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