Absolutely new to Xbees, fairly skilled at microcontrollers. I have just purchased the XBee Pro XSC OEM Development kit. I am looking to set these items up in a MINIMUM configuration - just power, Din and Dout, as they will be used in a stand-alone configuration and transmitting some short bursts of serial data between the two. I am interfacing these items to a Parallax Basic Stamp (BS2sx and BS2p40) which runs the application the XSCs need to communicate with.
I have checked out the schematic of the development board, but of course there’s a LOT of extra stuff in there, and I’m hoping that I don’t need to replicate any significant portion of that circuitry to get my application working!
I would benefit greatly from a schematic of such an application and some example code if possible. I am assuming that I will put some resistors on the data input pins to bring them from TTL to the 3v level, but I want to be certain I am understanding correctly that I can run these in what is basically a 4 pin connection configuration.
Thanks VERY much for your help to this utter newbie!
The first thing to say is that you do understand correctly: a four-pin connection is probably[1] enough. For encouragement, I’m attaching a GIF file with the complete circuit diagram of one circuit I’ve designed.
[1] If you ever want to tranmit lots of data, you’ll need to consider the serial data control flow options.
At first sight the circuit doesn’t look too simple, but that’s only because it has five temperature sensors in it.
Circuit notes:
The upper power rail comes from a cheap regulated mains supply at 9V. The voltage isn’t critical: enough for the voltage regulator VR1 to function, and not enough to make it overheat in generating the 3.3V at its output.
The capacitors either side of VR1 are as suggested in the manufacturer’s data sheet. Different models of regulator may have different recomendations.
This circuit is a remote sensor, so it has no host and therefore no connections to DIN and DOUT. It reads the temperatures of five temperature sensors at regular intervals and sends them to another XBee connected to my desktop computer. There, my program saves them for on-demand display.
The five temperature sensors are connected to five analog input lines on the XBee. The series resistors are as recommended by the manufacturer of the sensors, and the capacitors between each A-D and the VRef pin are as recommended in the XBee product manual.
H1 is just a three-pin header to bring power to the board. H2 is the header through which the main four temperature sensors are actually connected.
I could just have said “Connect VCC, Gnd, DIN and DOUT and you’re done” but I thought the circuit might be more convincing
One more comment though: when you build your circuit, it’s a very good idea if you can mount the XBee in header sockets. That way, when you want to update its firmware you can transfer it to a development board and do the update there. If you really want to solder the XBee in place, you’ll need to make extra provisions for firmware updates (ask again if you want to do this).
You also ask for example code, but you don’t say what languages you’re prepared to use. If you’re a Tcl or Python user I could be motivated to publish something, or if your language is Visual Basic then see recent posts. Otherwise, I’m afraid we haven’t yet established much of a code base in the forum.
This is very helpful, actually. It looks very simple - so simple, in fact, that I’m surprised. I have not worked with the LM35DZs before, but they are all outputting through the 2.2k resistor into an I/O pin. The XSC does not appear to have these I/Os, but only the Dout and Din. On the XSC, pins 17 - 20 are driven low and specified as “Do not connect”. But it would seem that if you can do that with your Xbee, my config should work fine.
Now all I need to do is get the PC communicating with the development board. So far, no luck with that right out of the box… but that’s the subject for another post!
Thanks again for your very helpful schematic - this is the kind of stuff that works best for me - schematics of working systems are worth hundreds of pages in the manual!
