This post will attempt to explain my A4WD-1 Rover project. I bought my Rover w/o electronics and outfitted it with GHM-16 Gear Head Motors, TRC-01 Off Road Tires, BAT-06 12V Battery and DE-05 (Sabertooth 2x12 Motor Controller).
Wireless communication between the A4WD and my Gateway Notebook is via XBee Series 1 RF modules operating at 9600 baud. Line of sight range is about 300 feet.
Testing at this point has been limited to sending commands to control the wheel drive motors, including combination commands to achieve skid steering. I have Sharp Range Sensors, Motor Encoders and a Pan & Tilt Servo ready to become this project’s phase 2.
The remote XBee’s serial data out pin is connected directly to the Sabertooth’s S1 connection. The XBee is a 3.3V device. Since the Sabertooth is operating in one-way communications receive only mode, 3.3V is more than sufficient to be interpreted as High (TTL Serial). This XBee is plugged into a SparkFun Regulated board (WRL-09132) which uses the Sabertooth’s 5V output to supply 3.3V to the XBee.
The base XBee is plugged into a SparkFun Explorer USB board (WRL-08687). This board contains a USB to Serial adapter which creates a virtual com port on my Gateway Notebook, as well as 5V to 3.3V converter for the XBee.
C# was used to create a 20 button on-screen pad capable of sending the 4 byte packets necessary to the Sabertooth operating in Mode 4.
The code is simple and was intended to test most of the A4WD drive motions. Combining left and right commands achieves skid steering. Feel free to modify it in any way you choose.
The Sabertooth’s address is set to 0x82 (130), mode 4 packetized serial by turning dip switches 3, 4 and 6 on. For this application both XBee’s are programmed to factory default.
ISSUE #1: the Sabertooth Motor Controller keeps performing the same function until it receives a new command. Should XBee transmission go out of range, the A4WD will keep going wherever it was headed. The Sabertooth can use connection S2 as a kill switch, but this project will require more intelligence at the remote end to use it. Perhaps phase 2 should be a remote Arduino.
ISSUE #2: One of my early experiments was a X10 wireless camera mounted to the A4WD. However it soon became apparent 2.4ghz cameras interfere with XBee 802.15.4 commuications. Bluetooth devices also operate in the 2.4ghz band and would probably also have communication problems. I suspect the issue lies more with the low cost of a X10 camera.
20 button control pad code:
[code]using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO.Ports;
using System.Threading;
namespace SerialPort
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
serialPort1.PortName = "COM4";
serialPort1.BaudRate = 9600;
serialPort1.DataBits = 8;
serialPort1.Parity = Parity.None;
serialPort1.StopBits = StopBits.One;
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
//left fwd stop
byte] bytesToSend = new byte[4] { 0x82, 0x00, 0x00, 0x02 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button2_Click(object sender, EventArgs e)
{
//left fwd 1/4 speed
byte] bytesToSend = new byte[4] { 0x82, 0x00, 0x20, 0x22 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button3_Click(object sender, EventArgs e)
{
//left fwd 1/2 speed
byte] bytesToSend = new byte[4] { 0x82, 0x00, 0x40, 0x42 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button4_Click(object sender, EventArgs e)
{
//left fwd 3/4 speed
byte] bytesToSend = new byte[4] { 0x82, 0x00, 0x60, 0x62 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button5_Click(object sender, EventArgs e)
{
//fwd full speed
byte] bytesToSend = new byte[4] { 0x82, 0x00, 0x7F, 0x01 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
//delay
Thread.Sleep(100);
byte] bytesToSend = new byte[4] { 0x82, 0x04, 0x7F, 0x05 };
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button6_Click(object sender, EventArgs e)
{
//left rev 1/4 speed
byte] bytesToSend = new byte[4] { 0x82, 0x01, 0x20, 0x23 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button7_Click(object sender, EventArgs e)
{
//left rev 1/2 speed
byte] bytesToSend = new byte[4] { 0x82, 0x01, 0x40, 0x43 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button8_Click(object sender, EventArgs e)
{
//left rev 3/4 speed
byte] bytesToSend = new byte[4] { 0x82, 0x01, 0x60, 0x63 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button9_Click(object sender, EventArgs e)
{
//left rev full speed
byte] bytesToSend = new byte[4] { 0x82, 0x01, 0x7F, 0x02 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button10_Click(object sender, EventArgs e)
{
//left rev stop
byte] bytesToSend = new byte[4] { 0x82, 0x01, 0x00, 0x03 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button20_Click(object sender, EventArgs e)
{
//right fwd stop
byte] bytesToSend = new byte[4] { 0x82, 0x04, 0x00, 0x06 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button19_Click(object sender, EventArgs e)
{
//right fwd 1/4 speed
byte] bytesToSend = new byte[4] { 0x82, 0x04, 0x20, 0x26 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button18_Click(object sender, EventArgs e)
{
//right fwd 1/2 speed
byte] bytesToSend = new byte[4] { 0x82, 0x04, 0x40, 0x46 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button17_Click(object sender, EventArgs e)
{
//right fwd 3/4 speed
byte] bytesToSend = new byte[4] { 0x82, 0x04, 0x60, 0x66 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button16_Click(object sender, EventArgs e)
{
//right fwd full speed
byte] bytesToSend = new byte[4] { 0x82, 0x04, 0x7F, 0x05 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button15_Click(object sender, EventArgs e)
{
//right rev 1/4 speed
byte] bytesToSend = new byte[4] { 0x82, 0x05, 0x20, 0x27 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button14_Click(object sender, EventArgs e)
{
//right rev 1/2 speed
byte] bytesToSend = new byte[4] { 0x82, 0x05, 0x40, 0x47 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button13_Click(object sender, EventArgs e)
{
//right rev 3/4 speed
byte] bytesToSend = new byte[4] { 0x82, 0x05, 0x60, 0x67 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button12_Click(object sender, EventArgs e)
{
//right rev full speed
byte] bytesToSend = new byte[4] { 0x82, 0x05, 0x7F, 0x06 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
private void button11_Click(object sender, EventArgs e)
{
//right rev stop
byte] bytesToSend = new byte[4] { 0x82, 0x05, 0x00, 0x07 };
serialPort1.Open();
serialPort1.Write(bytesToSend, 0, 4);
serialPort1.Close();
}
}
}[/code]
