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XBee 802.15.4 + FEZ Spider Gadgeteer



I’m developing a wireless sensing application for the Gadgeteer but I’m having trouble in making it wireless. I am using an FEZ Spider Mainboard, an XBee Adapter and XBees 802.15.4 radios. (I’m trying to make it work with an XBee S1 module and a 900MHz module, both 802.15.4).

My mission is to simply send a string to another radio (a base station), but I can’t get it done. I tried the default “xbee” library first to try to send data, but I couldn’t work out how it really worked for sending simple strings. Then I tried XBeeClient, a library that’s supposedly useful for this kind of “easy” applications. However, it didn’t really work. A weird message keeps appearing in the Debug Console: “Waiting for more bytes from serial port, message length indicates more bytes comming” even though I’m not trying to receive anything.

I found out later that this library, XBeeClient, was only supposed to work with XBee modules using “ZigBee”. My modules don’t have the full ZigBee stack, though. (Well, I think so. In XCTU, Digi’s software for setting up Xbees, the modules I use are not marked as “ZigBee”).

Do you know what I can do to make this simple application work, with the hardware I have?

Thank you very much!


@ hodoufo - Welcome!

It’s just simple serial commands, you dont need a library.
I’ll post some code in a moo.



@ Justin - Hey, thank you! I’d really appreciate that!


Righto - i cheat and use @ Iggmoe’s excellent SimpleSerial library, makes life easier -

And here is some code using it…

using System.IO.Ports;
using Microsoft.SPOT;
using GT = Gadgeteer;
using GTM = Gadgeteer.Modules;
using GTI = Gadgeteer.Interfaces;

namespace BalanceBee
    public partial class Program
        private SimpleSerial _xbeePort;
        private string[] _xBeeLines;

        void ProgramStarted()
            GT.Socket socket = GT.Socket.GetSocket(8, false, null, "");
            _xbeePort = new SimpleSerial(socket.SerialPortName, 57600, Parity.None, 8, StopBits.One);
            _xbeePort.DataReceived += new SerialDataReceivedEventHandler(XBeePortDataReceived);

        void XBeePortDataReceived(object sender, SerialDataReceivedEventArgs e)
            _xBeeLines = _xbeePort.Deserialize();
            foreach (string xBeeLine in _xBeeLines)
        private void SendXbee(string message)


I think there are also a couple of community made drivers for the xbee.
here is one of them


@ Justin - Hey, thank you for the help! Now I can send data to XCTU in another computer! :slight_smile:

However, when I receive data (which is not really required for my application, so I’m not so worried), it keeps catching this exception:

#### Exception System.Exception - CLR_E_WRONG_TYPE (3) ####
#### Message: 
#### System.Text.UTF8Encoding::GetChars [IP: 0000] ####
#### GadgeteerApp1.SimpleSerial::ReadExisting [IP: 000c] ####
#### GadgeteerApp1.SimpleSerial::Deserialize [IP: 0009] ####
#### GadgeteerApp1.Program::XBeePortDataReceived [IP: 000c] ####
#### System.IO.Ports.SerialPort::DataEventHandler [IP: 0012] ####

A first chance exception of type ‘System.Exception’ occurred in mscorlib.dll

Do you know what it means? I’m using XCTU’s terminal test the setup.

Thank you!


Post your full code and we’ll see if it’s obvious…


@ Justin - My full code is exactly what you posted


The error suggests that SimpleSerial is interpreting the incoming data as UTF-8, so if it’s falling over I would imagine the incoming data might not be UTF-8.


You may try my code. Not well writing but maybe help.

namespace DistanceTestGadgeteer_SDK20130214
    public partial class Program
        // This method is run when the mainboard is powered up or reset.
        //GT.Interfaces.Serial serial;
        double Sendcount = 0;
        double ReceiveCount = 1;
        int timestamp = 0;
        //GT.Timer timer = new GT.Timer(500);
        GT.Timer showTimeTimer = new GT.Timer(1000);

        void ProgramStarted()

            xBee.Configure(115200, GT.Interfaces.Serial.SerialParity.None,
            GT.Interfaces.Serial.SerialStopBits.One, 8);
            //serial = xBee.SerialLine;
            xBee.SerialLine.DataReceived += new GT.Interfaces.Serial.DataReceivedEventHandler(serial_DataReceived);                  
            showTimeTimer.Tick += new GT.Timer.TickEventHandler(showTimeTimer_Tick);
            Debug.Print("Program Started");

        void showTimeTimer_Tick(GT.Timer timer)
            var font = Resources.GetFont(Resources.FontResources.NinaB);
            timestamp = timestamp + 1;

            display_T35.SimpleGraphics.DisplayText("Time Stamp:" + timestamp.ToString(), font, GT.Color.White, 50, 50);
            display_T35.SimpleGraphics.DisplayText("Receive Number:" + ReceiveCount.ToString(), font, GT.Color.White, 50, 100);
        void serial_DataReceived(GT.Interfaces.Serial sender, System.IO.Ports.SerialData data)

            ReceiveCount = ReceiveCount + 1;
            var font = Resources.GetFont(Resources.FontResources.NinaB);
            int btr = xBee.SerialLine.BytesToRead;
            if (btr == 0) return;
            byte[] bytes = new byte[btr];
            byte[] idbytes = new byte[2];
            xBee.SerialLine.Read(bytes, 0, btr);
            idbytes[0] = bytes[5];
            idbytes[1] = bytes[4];
            string Text = new string(System.Text.Encoding.UTF8.GetChars(bytes));
            string id = new string(System.Text.Encoding.UTF8.GetChars(idbytes));// 

            UInt16 u = (UInt16)Microsoft.SPOT.Hardware.Utility.ExtractValueFromArray(idbytes, 0, 2);//Xbee ID
            //display_T35.SimpleGraphics.DisplayText(btr.ToString(), font, GT.Color.White, 50, 200);
            // display_T35.SimpleGraphics.DisplayText("Receive Number:"+ReceiveCount.ToString(), font, GT.Color.White, 50, 100);