SX52 protoboard and Xbee

Rsadeika

I am thinking about using an Xbee with an SX52 protoboard. Just wondering if anybody has done this, and is their anything to watch out for. I know that I will have to use at least two UART VPs, one for access to the Xbee, and one for access to the robot. I may also need one additional UART VP for access to a compass, not certain about using I2C or serial. I am trying to get some info in place before I actually go out and buy the Xbee units.

Thanks

Ray

Guenther Daubach

Ray,

using the XBee together with an SX is no problem in general - I have built up a couple of prototypes for one of my projects with the XBeePro modules. From the hardware point of view, be aware that the XBee modules come with connectors with a 2mm spacing (not 2.54 mm = 1/10"). So you may need matching sockets with this 2mm spacing. In addition, the XBee modules only allow for a maximum supply voltage of 3.3V, so you can't directly feed them from a 5 Volt supply you might be using for the SX.

You have two options:

1: Also run the SX side from a 3.3 Volt supply. This allows you to directly connect XBee I/O pins to SX I/O pins.

2: Run the SX side from a 5 Volt supply, and the XBee from a separate 3.3 Volt supply. Any XBee outputs can be directly fed into SX pins configured as inputs with their levels configured as TTL (the default). Any SX output pins should be connected to the XBee module input pins via serial resistors (I'm using 4.7 k). The XBee-internal clamp diodes across its inputs cut off the excessive output voltage from the SX pins and the serial resistors limit the current through the clamp diodes to a value below the allowed maximum.

At university, my professor for radio-communications explained the difference between wired and wireless communication like this:

Think of a long dachshund with its head located in NY, and its tail resting in LA. When you step on its tail in LA, it will yowl in NY - this is how wired communication works. Wireless communication is exactly the same - just without the dachshund .

The same is true with the XBee modules (the dachshunds in this case) - they simply replace the wire link between two units with serial asynchronous receivers/transmitters. Nevertheless, the XBee modules offer a lot more functionality than this, so it's a good idea to carefully study the XBee datasheets to learn more about the many additional features they offer.

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Greetings from Germany,

G