src/Device/Driver/FLARM/Mode.cpp

   1 /*
   2 Copyright_License {
   3
   4   XCSoar Glide Computer - http://www.xcsoar.org/
   5   Copyright (C) 2000-2013 The XCSoar Project
   6   A detailed list of copyright holders can be found in the file "AUTHORS".
   7
   8   This program is free software; you can redistribute it and/or
   9   modify it under the terms of the GNU General Public License
  10   as published by the Free Software Foundation; either version 2
  11   of the License, or (at your option) any later version.
  12
  13   This program is distributed in the hope that it will be useful,
  14   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16   GNU General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with this program; if not, write to the Free Software
  20   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 }
  22 */
  23
  24 #include "Device.hpp"
  25 #include "Device/Port/Port.hpp"
  26 #include "Operation/Operation.hpp"
  27
  28 bool
  29 FlarmDevice::EnableNMEA(OperationEnvironment &env)
  30 {
  31   switch (mode) {
  32   case Mode::UNKNOWN:
  33     /* device could be in binary mode, we don't know, but this is the
  34        best we can do: */
  35     if (!BinaryReset(env, 500))
  36       return false;
  37
  38     mode = Mode::NMEA;
  39
  40     /* request self-test results and version information from FLARM */
  41     Send("PFLAE,R", env);
  42     Send("PFLAV,R", env);
  43     return true;
  44
  45   case Mode::NMEA:
  46     return true;
  47
  48   case Mode::TEXT:
  49     /* no real difference between NMEA and TEXT; in mode==TEXT, the
  50        Port thread is stopped, but the caller is responsible for
  51        restarting it, which means there's nothing to do for us */
  52     mode = Mode::NMEA;
  53     return true;
  54
  55   case Mode::BINARY:
  56     if (!BinaryReset(env, 500)) {
  57       mode = Mode::UNKNOWN;
  58       return false;
  59     }
  60
  61     mode = Mode::NMEA;
  62     return true;
  63   }
  64
  65   gcc_unreachable();
  66   assert(false);
  67   return false;
  68 }
  69
  70 bool
  71 FlarmDevice::BinaryMode(OperationEnvironment &env)
  72 {
  73   if (mode == Mode::BINARY)
  74     return true;
  75
  76   port.StopRxThread();
  77
  78   // "Binary mode is engaged by sending the text command "$PFLAX"
  79   // (including a newline character) to Flarm."
  80   if (!Send("PFLAX", env))
  81     return false;
  82
  83   // Remember that we should now be in binary mode (for further assert() calls)
  84   mode = Mode::BINARY;
  85
  86   // "After switching, connection should again be checked by issuing a ping."
  87   // Testing has revealed that switching the protocol takes a certain amount
  88   // of time (around 1.5 sec). Due to that it is recommended to issue new pings
  89   // for a certain time until the ping is ACKed properly or a timeout occurs.
  90   for (unsigned i = 0; i < 10; ++i) {
  91     if (env.IsCancelled()) {
  92       BinaryReset(env, 200);
  93       mode = Mode::UNKNOWN;
  94       return false;
  95     }
  96
  97     if (BinaryPing(env, 500))
  98       // We are now in binary mode and have verified that with a binary ping
  99       return true;
 100   }
 101
 102   // Apparently the switch to binary mode didn't work
 103   mode = Mode::UNKNOWN;
 104   return false;
 105 }