ublox6: Initial implementation

jrvandr: removed unnecessary mraa_init() and mraa_deinit()

The module implements support for the ublox-6 GPS sensor.  It was
tested on a Grove GPS device.

This module simply allows data to be retrieved from the device in the
form of NMEA sentences, and provides a method to write commands to the
device for configuration purposes.

It does not attempt to parse NMEA data -- that is a project in itself.
There are libraries available on the Internet, such as tinyGPS++ that
can handle that for you.

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Zion Orent <zorent@ics.com>
Signed-off-by: John Van Drasek <john.r.van.drasek@intel.com>

src/ublox6/ublox6.cxx

@@ -0,0 +1,140 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <iostream>
+
+#include "ublox6.h"
+
+using namespace upm;
+using namespace std;
+
+Ublox6::Ublox6(int uart, const char *tty) :
+  m_ttyFd(-1)
+{
+  mraa_init();
+
+  if ( !(m_uart = mraa_uart_init(uart)) )
+    {
+      cerr << __FUNCTION__ << ": mraa_uart_init() failed" << endl;
+      return;
+    }
+
+  // now open the tty
+  if ( (m_ttyFd = open(tty, O_RDWR)) == -1)
+    {
+      cerr << __FUNCTION__ << ": open of " << tty << " failed: " 
+           << strerror(errno) << endl;
+      return;
+    }
+}
+
+Ublox6::~Ublox6()
+{
+  if (m_ttyFd != -1)
+    close(m_ttyFd);
+}
+
+bool Ublox6::dataAvailable()
+{
+  if (m_ttyFd == -1)
+    return false;
+
+  struct timeval timeout;
+
+  // no waiting
+  timeout.tv_sec = 0;
+  timeout.tv_usec = 0;
+
+  int nfds;  
+  fd_set readfds;
+
+  FD_ZERO(&readfds);
+
+  FD_SET(m_ttyFd, &readfds);
+  
+  if (select(m_ttyFd + 1, &readfds, NULL, NULL, &timeout) > 0)
+    return true;                // data is ready
+  else
+    return false;
+}
+
+int Ublox6::readData(char *buffer, size_t len)
+{
+  if (m_ttyFd == -1)
+    return(-1);
+
+  int rv = read(m_ttyFd, buffer, len);
+
+  if (rv < 0)
+    cerr << __FUNCTION__ << ": read failed: " << strerror(errno) << endl;
+
+  return rv;
+}
+
+int Ublox6::writeData(char * buffer, size_t len)
+{
+  if (m_ttyFd == -1)
+    return(-1);
+
+  int rv = write(m_ttyFd, buffer, len);
+
+  if (rv < 0)
+    {
+      cerr << __FUNCTION__ << ": write failed: " << strerror(errno) << endl;
+      return rv;
+    }
+
+  tcdrain(m_ttyFd);
+
+  return rv;
+}
+
+bool Ublox6::setupTty(speed_t baud)
+{
+  if (m_ttyFd == -1)
+    return(false);
+  
+  struct termios termio;
+
+  // get current modes
+  tcgetattr(m_ttyFd, &termio);
+
+  // setup for a 'raw' mode.  81N, no echo or special character
+  // handling, such as flow control.
+  cfmakeraw(&termio);
+
+  // set our baud rates
+  cfsetispeed(&termio, baud);
+  cfsetospeed(&termio, baud);
+
+  // make it so
+  int rv;
+  if ( (rv = tcsetattr(m_ttyFd, TCSAFLUSH, &termio)) < 0)
+    {
+      cerr << __FUNCTION__ << ": tcsetattr failed: " << strerror(errno) << endl;
+      return false;
+    }
+
+  return true;
+}