/**
* Temporary method to avoid clutter in main. Returns null if the packet is illegal!! This method
* will take care of removing DLE-stuffing from the packet.
*/
public static int[] readPacket(BufferedInputStream input) {
int[] packet;
try {
int read = input.read();
if (read != DLE) return null;
int id = input.read();
int length = input.read();
packet = new int[length + 6];
if (length == 16) input.read();
packet[0] = DLE;
packet[1] = id;
packet[2] = length;
for (int i = 0; i < length + 1; i++) {
packet[i + 3] = input.read();
if (packet[i + 3] == DLE) { // Remove DLE-stuffing
input.read();
}
}
packet[packet.length - 2] = input.read();
packet[packet.length - 1] = input.read();
} catch (IOException e) {
System.out.println("Error while reading packet from GPS.");
return null;
}
return packet;
}
public static void main(String args[]) {
// Command to turn of GPS
int[] turn_off = new int[8];
turn_off[0] = DLE;
turn_off[1] = Pid_Command_Packet;
turn_off[2] = 2; // Length of data
turn_off[3] = Cmnd_Turn_Off_Pwr;
turn_off[4] = 0;
turn_off[6] = DLE;
turn_off[7] = ETX;
calcChecksum(turn_off);
System.out.println("Turn off checksum: " + turn_off[5]);
// Command to ask GPS for time data.
int[] transfer_time = new int[8];
transfer_time[0] = DLE;
transfer_time[1] = Pid_Command_Packet;
transfer_time[2] = 2;
transfer_time[3] = Cmnd_Transfer_Time;
transfer_time[4] = 0;
transfer_time[6] = DLE;
transfer_time[7] = ETX;
calcChecksum(transfer_time);
System.out.println("Transfer time" + transfer_time[5]);
// Command to make a product request to the GPS.
int[] product_request = new int[6];
product_request[0] = DLE;
product_request[1] = Pid_Product_Rqst;
product_request[2] = 0;
product_request[4] = DLE;
product_request[5] = ETX;
calcChecksum(product_request);
System.out.println("Product request:" + product_request[5]);
// Command to ask GPS for position data
int[] transfer_position = new int[8];
transfer_position[0] = DLE;
transfer_position[1] = Pid_Command_Packet;
transfer_position[2] = 2;
transfer_position[3] = Cmnd_Transfer_Posn;
transfer_position[4] = 0;
transfer_position[6] = DLE;
transfer_position[7] = ETX;
calcChecksum(transfer_position);
// Command to ask the GPS to start transmitting PVT data
int[] start_PVT = new int[8];
start_PVT[0] = DLE;
start_PVT[1] = Pid_Command_Packet;
start_PVT[2] = 2;
start_PVT[3] = Cmnd_Start_Pvt_Data;
start_PVT[4] = 0;
start_PVT[6] = DLE;
start_PVT[7] = ETX;
calcChecksum(start_PVT);
// Acknowledge-packet.
int[] ack = new int[8];
ack[0] = DLE;
ack[1] = Pid_Ack_Byte;
ack[2] = 2;
ack[4] = 0;
ack[6] = DLE;
ack[7] = ETX;
SerialPort port;
BufferedInputStream input;
BufferedOutputStream output;
System.out.println("Using COM1.");
// Open port.
try {
port =
(SerialPort) CommPortIdentifier.getPortIdentifier("COM1").open("dk.itu.haas.GPS", 3000);
} catch (NoSuchPortException e) {
System.out.println("No such port!\n" + e.getMessage());
return;
} catch (PortInUseException e) {
System.out.println("Port already in use! (??!)\n" + e.getMessage());
return;
}
try {
input = new BufferedInputStream(port.getInputStream());
output = new BufferedOutputStream(port.getOutputStream());
} catch (IOException e) {
System.out.println("IOException... ");
return;
}
System.out.println("Sending:");
printPacket(turn_off);
sendPacket(output, turn_off);
/*
printPacket(transfer_position);
sendPacket(output, transfer_position);
*/
/*
printPacket(start_PVT);
sendPacket(output, start_PVT);
*/
/*
printPacket(product_request);
sendPacket(output, product_request);
*/
System.out.println("--");
int[] packet;
try {
Thread.sleep(500);
} catch (InterruptedException e) {
}
try {
while (input.available() > 0) {
packet = readPacket(input);
if (packet != null) {
System.out.println("Received:");
printPacket(packet);
// Send acknowledge.
ack[3] = packet[1];
calcChecksum(ack);
sendPacket(output, ack);
System.out.println("--");
} else {
System.out.println("No packet received.");
}
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
}
}
} catch (IOException e) {
System.out.println("IOError!");
return;
}
}