bool
FlarmDevice::EnableNMEA(OperationEnvironment &env)
{
switch (mode) {
case Mode::UNKNOWN:
/* device could be in binary mode, we don't know, but this is the
best we can do: */
if (!BinaryReset(env, 500))
return false;
mode = Mode::NMEA;
/* request self-test results and version information from FLARM */
Send("PFLAE,R", env);
Send("PFLAV,R", env);
return true;
case Mode::NMEA:
return true;
case Mode::TEXT:
/* no real difference between NMEA and TEXT; in mode==TEXT, the
Port thread is stopped, but the caller is responsible for
restarting it, which means there's nothing to do for us */
mode = Mode::NMEA;
return true;
case Mode::BINARY:
if (!BinaryReset(env, 500)) {
mode = Mode::UNKNOWN;
return false;
}
mode = Mode::NMEA;
return true;
}
gcc_unreachable();
assert(false);
return false;
}
bool
FlarmDevice::EnableNMEA(OperationEnvironment &env)
{
switch (mode) {
case Mode::UNKNOWN:
/* device could be in binary mode, we don't know, but this is the
best we can do: */
if (!BinaryReset(env, 500))
return false;
mode = Mode::NMEA;
return true;
case Mode::NMEA:
return true;
case Mode::TEXT:
/* no real difference between NMEA and TEXT; in mode==TEXT, the
Port thread is stopped, but the caller is responsible for
restarting it, which means there's nothing to do for us */
mode = Mode::NMEA;
return true;
case Mode::BINARY:
if (!BinaryReset(env, 500)) {
mode = Mode::UNKNOWN;
return false;
}
mode = Mode::NMEA;
return true;
}
/* unreachable */
assert(false);
return false;
}
bool
FlarmDevice::BinaryMode(OperationEnvironment &env)
{
if (mode == Mode::BINARY)
return true;
port.StopRxThread();
// "Binary mode is engaged by sending the text command "$PFLAX"
// (including a newline character) to Flarm."
if (!Send("PFLAX", env))
return false;
// Remember that we should now be in binary mode (for further assert() calls)
mode = Mode::BINARY;
// "After switching, connection should again be checked by issuing a ping."
// Testing has revealed that switching the protocol takes a certain amount
// of time (around 1.5 sec). Due to that it is recommended to issue new pings
// for a certain time until the ping is ACKed properly or a timeout occurs.
for (unsigned i = 0; i < 10; ++i) {
if (env.IsCancelled()) {
BinaryReset(env, 200);
mode = Mode::UNKNOWN;
return false;
}
if (BinaryPing(env, 500))
// We are now in binary mode and have verified that with a binary ping
return true;
}
// Apparently the switch to binary mode didn't work
mode = Mode::UNKNOWN;
return false;
}