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Usando GPS Bluetooth

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Artigo
Tradução:
Originado de Using Bluetooth GPS
Por leandrodds
Última alteração feita por hamishwillee em 30 May 2013

Como Usar um GPS Bluetooth

A classe GPS mostra como usar um dispositivo GPS Bluetooth e ler informações de localização deste. Ela mostra um dialogo de seleção para o usuário e inicia o recebimento de dados do dispositivo selecionado. Atualmente, ela apenas processa a mensagem RMC que é requerida em todos os dispositivos GPS. Isto dá a informação de latitude, longitude, direção e velocidade mas não altitude nem diluição.

Você precisa implementar mensagens para perda de signal, etc, se você deseja mostrá-las ao usuário.

Você também pode usar o método Parse() para converter os valores recebidos para graus, minutos e segundos, assim como um valor inteiro combinado multiplicado por 65536.

Este exemplo assume que o dispositivo GPS usa o canal RFCOMM 1 como canal de dados. Este tem sido o caso de todos os dispositivos que eu usei, então é uma suposição segura.

GPS.h

#ifndef GPS_H_
#define GPS_H_
 
#include <e32std.h>
#include <btmanclient.h>
#include <btextnotifiers.h>
#include <es_sock.h>
#include <in_sock.h>
#include <bt_sock.h>
 
class GPS : public CActive
{
public:
GPS();
virtual ~GPS();
void ConstructL();
 
void DoCancel();
void RunL();
 
TPtrC Lat();
TPtrC Lon();
 
TInt speed, heading;
 
private:
TBool Active;
TBuf8<32> lat, lon;
 
TBuf8<256> line;
TBuf8<32> data;
int state;
RSocket iSendingSocket;
RSocketServ iSocketServer;
};
 
#endif /*GPS_H_*/

GPS.cpp

#include "GPS.h"
#include <e32math.h>
 
_LIT8(ZERO, "0");
_LIT(RFCOMM, "RFCOMM");
_LIT8(KGPS, "GPS");
 
void Parse(TDesC8 &data, TInt &deg, TInt &min, TInt &sec, TInt32 &whole)
{
TLex8 lex(data);
 
lex.Val(deg);
lex.Inc();
lex.Val(min);
sec = min * 60;
int l = (data.Length() - data.Find(_L8(".")));
int x = 1;
while (l-- > 0)
x *= 10;
sec /= x/100;
 
min = deg % 100;
deg /= 100;
 
whole = deg * 65536 + (min * 65536 / 60) + (sec * 65536 / 36000);
}
 
GPS::GPS() : CActive(EPriorityLow)
{
state = 0;
}
 
GPS::~GPS()
{
TRAPD(err, Cancel());
TRAP(err, Deque());
}
 
void GPS::RunL()
{
int i, j;
 
if (iStatus == KErrNone)
{
if (state == 1)
{
state = 2;
line.Zero();
iSendingSocket.Read(data, iStatus);
SetActive();
}
else if (state == 2)
{
int rpos = 0;
 
while ((rpos = data.Locate('\r')) != KErrNotFound)
{
line.Append(data.Left(rpos));
if (data.Length() > rpos + 2)
{
if (data[rpos + 1] == '\n')
data.Copy(data.Mid(rpos+2));
else
data.Copy(data.Mid(rpos+1));
}
else
{
data.Zero();
}
 
if (line.Length() > 10)
{
// RMC - lat, lon, speed
if ((line[3] == 'R') && (line[4] == 'M') && (line[5] == 'C'))
{
j = i = 0;
while ((i < line.Length()) && (line[i] != ','))
i++;
i++;
 
j = i;
while ((i < line.Length()) && (line[i] != ','))
i++;
i++;
 
// If there is no signal, this is not A
if (line[i] != 'A')
{
lat.Copy(ZERO);
lon.Copy(ZERO);
latdeg = londeg = latmin = lonmin = latsec = lonsec = 0;
line.Zero();
iSendingSocket.Read(data, iStatus);
SetActive();
return;
}
 
while ((i < line.Length()) && (line[i] != ','))
i++;
i++;
j = i;
while ((i < line.Length()) && (line[i] != ','))
i++;
 
// Copy latitude from the message
lat.Copy(line.Mid(j, i-j));
// If it's southern hemisphere, negate the value
if (line[i+1] == 'S')
lat.Insert(0, _L8("-"));
 
i += 3;
j = i;
while ((i < line.Length()) && (line[i] != ','))
i++;
 
// Copy longitude from the message
lon.Copy(line.Mid(j, i-j));
// If it's western hemisphere, negate the value
if (line[i+1] == 'W')
lon.Insert(0, _L8("-"));
 
i += 3;
j = i;
while ((i < line.Length()) && (line[i] != ','))
i++;
 
// Read speed from the message
TLex8 lex(line.Mid(j, i-j));
lex.Val(speed);
speed *= 10;
if (lex.Peek() == '.')
{
lex.Inc();
if (lex.Peek() != 0)
speed += ((int)lex.Peek() - '0');
}
// Convert speed from knots to km/h
speed *= 1852;
speed /= 1000;
 
i++;
j = i;
while ((i < line.Length()) && (line[i] != ','))
i++;
 
// Read heading from the message
lex.Assign(line.Mid(j, i-j));
lex.Val(heading);
heading *= 10;
// Check if it's not integer
if (lex.Peek() == '.')
{
lex.Inc();
if (lex.Peek() != 0)
heading += ((int)lex.Peek() - '0');
}
}
}
 
line.Zero();
}
 
line.Append(data);
 
iSendingSocket.Read(data, iStatus);
SetActive();
}
}
// Error occurred...
else
{
lat.Copy(ZERO);
lon.Copy(ZERO);
}
}
 
void GPS::DoCancel()
{
if (state > 0)
iSendingSocket.Close();
iSocketServer.Close();
}
 
void GPS::ConstructL()
{
TBTDeviceResponseParamsPckg resultPckg;
 
CActiveScheduler::Add(this);
 
// 1. Create a notifier
RNotifier notif;
User::LeaveIfError(notif.Connect());
 
if (gpsid.Length() == 0)
{
state = 0;
// 2. Start the device selection plug-in
TBTDeviceSelectionParams selectionFilter;
TUUID targetServiceClass(0x2345);
selectionFilter.SetUUID(targetServiceClass);
TBTDeviceSelectionParamsPckg pckg(selectionFilter);
TRequestStatus status;
notif.StartNotifierAndGetResponse(status,
KDeviceSelectionNotifierUid, pckg, resultPckg);
User::After(2000000);
 
// 3. Extract device name if it was returned
User::WaitForRequest(status);
 
User::LeaveIfError(iSocketServer.Connect());
 
if (status.Int() == KErrNone)
{
User::LeaveIfError(iSendingSocket.Open(iSocketServer,
RFCOMM));
TBTSockAddr address;
gpsid.Copy(resultPckg().BDAddr().Des());
address.SetBTAddr(resultPckg().BDAddr());
// GPS devices usually use port 1 as data channel
// so we don't have to query it
address.SetPort(1);
 
state = 1;
iSendingSocket.Connect(address, iStatus);
SetActive();
}
else
{
CHainMAppView::Static()->Notification(EGPSNotFound);
}
}
else
{
User::LeaveIfError(iSocketServer.Connect());
User::LeaveIfError(iSendingSocket.Open(iSocketServer, RFCOMM));
 
TBTSockAddr address;
TBTDevAddr a(gpsid);
address.SetBTAddr(a);
address.SetPort(1);
 
state = 1;
iSendingSocket.Connect(address, iStatus);
SetActive();
}
}
 
TPtrC GPS::Lat()
{
return lat;
}
 
TPtrC GPS::Lon()
{
return lon;
}
This page was last modified on 30 May 2013, at 04:41.
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