ardupilot/ArduPlane/failsafe.pde

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// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
* failsafe support
* Andrew Tridgell, December 2011
*/
/*
* our failsafe strategy is to detect main loop lockup and switch to
* passing inputs straight from the RC inputs to RC outputs.
*/
/*
* this failsafe_check function is called from the core timer interrupt
* at 1kHz.
*/
void failsafe_check(uint32_t tnow)
{
static uint16_t last_mainLoop_count;
static uint32_t last_timestamp;
static bool in_failsafe;
if (mainLoop_count != last_mainLoop_count) {
// the main loop is running, all is OK
last_mainLoop_count = mainLoop_count;
last_timestamp = tnow;
in_failsafe = false;
return;
}
if (tnow - last_timestamp > 200000) {
// we have gone at least 0.2 seconds since the main loop
// ran. That means we're in trouble, or perhaps are in
// an initialisation routine or log erase. Start passing RC
// inputs through to outputs
in_failsafe = true;
}
if (in_failsafe && tnow - last_timestamp > 20000) {
// pass RC inputs to outputs every 20ms
last_timestamp = tnow;
hal.rcin->clear_overrides();
channel_roll->radio_out = channel_roll->read();
channel_pitch->radio_out = channel_pitch->read();
channel_throttle->radio_out = channel_throttle->read();
channel_rudder->radio_out = channel_rudder->read();
// setup secondary output channels that don't have
// corresponding input channels
RC_Channel_aux::set_servo_out(RC_Channel_aux::k_aileron, channel_roll->radio_out);
RC_Channel_aux::set_servo_out(RC_Channel_aux::k_elevator, channel_pitch->radio_out);
RC_Channel_aux::set_servo_out(RC_Channel_aux::k_rudder, channel_rudder->radio_out);
if (g.vtail_output != MIXING_DISABLED) {
channel_output_mixer(g.vtail_output, channel_pitch->radio_out, channel_rudder->radio_out);
} else if (g.elevon_output != MIXING_DISABLED) {
channel_output_mixer(g.elevon_output, channel_pitch->radio_out, channel_roll->radio_out);
}
if (!demoing_servos) {
channel_roll->output();
}
channel_pitch->output();
channel_throttle->output();
channel_rudder->output();
// setup secondary output channels that do have
// corresponding input channels
RC_Channel_aux::copy_radio_in_out(RC_Channel_aux::k_manual, true);
RC_Channel_aux::copy_radio_in_out(RC_Channel_aux::k_aileron_with_input, true);
RC_Channel_aux::copy_radio_in_out(RC_Channel_aux::k_elevator_with_input, true);
}
}