ardupilot/libraries/SRV_Channel/SRV_Channels.cpp

/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
/*
  SRV_Channel.cpp - object to separate input and output channel
  ranges, trim and reversal
 */

#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#include <AP_Scheduler/AP_Scheduler.h>
#include <AP_Vehicle/AP_Vehicle_Type.h>

#include "SRV_Channel.h"
#include <AP_Logger/AP_Logger.h>
#include <AP_KDECAN/AP_KDECAN.h>

#if HAL_MAX_CAN_PROTOCOL_DRIVERS
  #include <AP_CANManager/AP_CANManager.h>
  #include <AP_DroneCAN/AP_DroneCAN.h>
  #include <AP_PiccoloCAN/AP_PiccoloCAN.h>
#endif

#if NUM_SERVO_CHANNELS == 0
#pragma GCC diagnostic ignored "-Wtype-limits"
#endif

extern const AP_HAL::HAL& hal;

SRV_Channel *SRV_Channels::channels;
SRV_Channels *SRV_Channels::_singleton;

#if AP_VOLZ_ENABLED
AP_Volz_Protocol *SRV_Channels::volz_ptr;
#endif

#if AP_SBUSOUTPUT_ENABLED
AP_SBusOut *SRV_Channels::sbus_ptr;
#endif

#if AP_ROBOTISSERVO_ENABLED
AP_RobotisServo *SRV_Channels::robotis_ptr;
#endif

#if AP_FETTEC_ONEWIRE_ENABLED
AP_FETtecOneWire *SRV_Channels::fetteconwire_ptr;
#endif

uint16_t SRV_Channels::override_counter[NUM_SERVO_CHANNELS];

#if HAL_SUPPORT_RCOUT_SERIAL
AP_BLHeli *SRV_Channels::blheli_ptr;
#endif

uint32_t SRV_Channels::disabled_mask;
uint32_t SRV_Channels::digital_mask;
uint32_t SRV_Channels::reversible_mask;
uint32_t SRV_Channels::invalid_mask;

bool SRV_Channels::disabled_passthrough;
bool SRV_Channels::initialised;
bool SRV_Channels::emergency_stop;
Bitmask<SRV_Channel::k_nr_aux_servo_functions> SRV_Channels::function_mask;
SRV_Channels::srv_function SRV_Channels::functions[SRV_Channel::k_nr_aux_servo_functions];
SRV_Channels::slew_list *SRV_Channels::_slew;

const AP_Param::GroupInfo SRV_Channels::var_info[] = {
#if (NUM_SERVO_CHANNELS >= 1)
    // @Group: 1_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[0], "1_",  1, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 2)
    // @Group: 2_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[1], "2_",  2, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 3)
    // @Group: 3_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[2], "3_",  3, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 4)
    // @Group: 4_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[3], "4_",  4, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 5)
    // @Group: 5_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[4], "5_",  5, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 6)
    // @Group: 6_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[5], "6_",  6, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 7)
    // @Group: 7_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[6], "7_",  7, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 8)
    // @Group: 8_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[7], "8_",  8, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 9)
    // @Group: 9_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[8], "9_",  9, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 10)
    // @Group: 10_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[9], "10_",  10, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 11)
    // @Group: 11_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[10], "11_",  11, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 12)
    // @Group: 12_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[11], "12_",  12, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 13)
    // @Group: 13_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[12], "13_",  13, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 14)
    // @Group: 14_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[13], "14_",  14, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 15)
    // @Group: 15_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[14], "15_",  15, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 16)
    // @Group: 16_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[15], "16_",  16, SRV_Channels, SRV_Channel),
#endif

#ifndef  HAL_BUILD_AP_PERIPH
    // @Param{Plane}: _AUTO_TRIM
    // @DisplayName: Automatic servo trim
    // @Description: This enables automatic servo trim in flight. Servos will be trimed in stabilized flight modes when the aircraft is close to level. Changes to servo trim will be saved every 10 seconds and will persist between flights. The automatic trim won't go more than 20% away from a centered trim.
    // @Values: 0:Disable,1:Enable
    // @User: Advanced
    AP_GROUPINFO_FRAME("_AUTO_TRIM",  17, SRV_Channels, auto_trim, 0, AP_PARAM_FRAME_PLANE),
#endif

    // @Param: _RATE
    // @DisplayName: Servo default output rate
    // @Description: Default output rate in Hz for all PWM outputs.
    // @Range: 25 400
    // @User: Advanced
    // @Units: Hz
    AP_GROUPINFO("_RATE",  18, SRV_Channels, default_rate, 50),

#if AP_VOLZ_ENABLED
    // @Group: _VOLZ_
    // @Path: ../AP_Volz_Protocol/AP_Volz_Protocol.cpp
    AP_SUBGROUPINFO(volz, "_VOLZ_",  19, SRV_Channels, AP_Volz_Protocol),
#endif

#if AP_SBUSOUTPUT_ENABLED
    // @Group: _SBUS_
    // @Path: ../AP_SBusOut/AP_SBusOut.cpp
    AP_SUBGROUPINFO(sbus, "_SBUS_",  20, SRV_Channels, AP_SBusOut),
#endif

#if HAL_SUPPORT_RCOUT_SERIAL
    // @Group: _BLH_
    // @Path: ../AP_BLHeli/AP_BLHeli.cpp
    AP_SUBGROUPINFO(blheli, "_BLH_",  21, SRV_Channels, AP_BLHeli),
#endif

#if AP_ROBOTISSERVO_ENABLED
    // @Group: _ROB_
    // @Path: ../AP_RobotisServo/AP_RobotisServo.cpp
    AP_SUBGROUPINFO(robotis, "_ROB_",  22, SRV_Channels, AP_RobotisServo),
#endif

#if AP_FETTEC_ONEWIRE_ENABLED
    // @Group: _FTW_
    // @Path: ../AP_FETtecOneWire/AP_FETtecOneWire.cpp
    AP_SUBGROUPINFO(fetteconwire, "_FTW_",  25, SRV_Channels, AP_FETtecOneWire),
#endif

    // @Param: _DSHOT_RATE
    // @DisplayName: Servo DShot output rate
    // @Description: DShot output rate for all outputs as a multiple of the loop rate. 0 sets the output rate to be fixed at 1Khz for low loop rates. This value should never be set below 500Hz.
    // @Values: 0:1Khz,1:loop-rate,2:double loop-rate,3:triple loop-rate,4:quadruple loop rate
    // @User: Advanced
    AP_GROUPINFO("_DSHOT_RATE",  23, SRV_Channels, dshot_rate, 0),

    // @Param: _DSHOT_ESC
    // @DisplayName: Servo DShot ESC type
    // @Description: DShot ESC type for all outputs. The ESC type affects the range of DShot commands available and the bit widths used. None means that no dshot commands will be executed. Some ESC types support Extended DShot Telemetry (EDT) which allows telemetry other than RPM data to be returned when using bi-directional dshot. If you enable EDT you must install EDT capable firmware for correct operation.
    // @Values: 0:None,1:BLHeli32/Kiss,2:BLHeli_S,3:BLHeli32/Kiss+EDT,4:BLHeli_S+EDT
    // @User: Advanced
    AP_GROUPINFO("_DSHOT_ESC",  24, SRV_Channels, dshot_esc_type, 0),

    // @Param: _GPIO_MASK
    // @DisplayName: Servo GPIO mask
    // @Description: Bitmask of outputs which will be available as GPIOs. Any output with either the function set to -1 or with the corresponding bit set in this mask will be available for use as a GPIO pin
    // @Bitmask: 0:Servo 1, 1:Servo 2, 2:Servo 3, 3:Servo 4, 4:Servo 5, 5:Servo 6, 6:Servo 7, 7:Servo 8, 8:Servo 9, 9:Servo 10, 10:Servo 11, 11:Servo 12, 12:Servo 13, 13:Servo 14, 14:Servo 15, 15:Servo 16, 16:Servo 17, 17:Servo 18, 18:Servo 19, 19:Servo 20, 20:Servo 21, 21:Servo 22, 22:Servo 23, 23:Servo 24, 24:Servo 25, 25:Servo 26, 26:Servo 27, 27:Servo 28, 28:Servo 29, 29:Servo 30, 30:Servo 31, 31:Servo 32
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("_GPIO_MASK",  26, SRV_Channels, gpio_mask, 0),  

    // indexes 27-43 used by SERVO_32_ENABLEd group of params
 
    // @Param: _RC_FS_MSK
    // @DisplayName: Servo RC Failsafe Mask
    // @Description: Bitmask of scaled passthru output function which will be set to their trim value during rc failsafe instead of holding their last position before failsafe.
    // @Bitmask: 0:RCIN1Scaled, 1:RCIN2Scaled, 2:RCIN3Scaled, 3:RCIN4Scaled, 4:RCIN5Scaled, 5:RCIN6Scaled, 6:RCIN7Scaled, 7:RCIN8Scaled, 8:RCIN9Scaled, 9:RCIN10Scaled, 10:RCIN11Scaled, 11:SRCIN12Scaled, 12:RCIN13Scaled, 13:RCIN14Scaled, 14:RCIN15Scaled, 15:RCIN16Scaled
    // @User: Advanced
    AP_GROUPINFO("_RC_FS_MSK", 44, SRV_Channels, rc_fs_mask, 0),
 
#if (NUM_SERVO_CHANNELS >= 17)
    // @Param: _32_ENABLE
    // @DisplayName: Enable outputs 17 to 31
    // @Description: This allows for up to 32 outputs, enabling parameters for outputs above 16
    // @User: Advanced
    // @Values: 0:Disabled,1:Enabled
    AP_GROUPINFO_FLAGS("_32_ENABLE", 43, SRV_Channels, enable_32_channels, 0, AP_PARAM_FLAG_ENABLE),
#endif

#if (NUM_SERVO_CHANNELS >= 17)
    // @Group: 17_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[16], "17_",  27, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 18)
    // @Group: 18_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[17], "18_", 28, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 19)
    // @Group: 19_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[18], "19_",  29, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 20)
    // @Group: 20_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[19], "20_",  30, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 21)
    // @Group: 21_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[20], "21_",  31, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 22)
    // @Group: 22_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[21], "22_",  32, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 23)
    // @Group: 23_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[22], "23_",  33, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 24)
    // @Group: 24_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[23], "24_",  34, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 25)
    // @Group: 25_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[24], "25_",  35, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 26)
    // @Group: 26_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[25], "26_",  36, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 27)
    // @Group: 27_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[26], "27_",  37, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 28)
    // @Group: 28_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[27], "28_",  38, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 29)
    // @Group: 29_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[28], "29_",  39, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 30)
    // @Group: 30_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[29], "30_",  40, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 31)
    // @Group: 31_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[30], "31_",  41, SRV_Channels, SRV_Channel),
#endif

#if (NUM_SERVO_CHANNELS >= 32)
    // @Group: 32_
    // @Path: SRV_Channel.cpp
    AP_SUBGROUPINFO(obj_channels[31], "32_",  42, SRV_Channels, SRV_Channel),
#endif

    AP_GROUPEND
};

/*
  constructor
 */
SRV_Channels::SRV_Channels(void)
{
    _singleton = this;
    channels = obj_channels;

    // set defaults from the parameter table
    AP_Param::setup_object_defaults(this, var_info);

    // setup ch_num on channels
    for (uint8_t i=0; i<NUM_SERVO_CHANNELS; i++) {
        channels[i].ch_num = i;
#if NUM_SERVO_CHANNELS > 16
        if (i >= 16) {
            // default to GPIO, this disables the pin and stops logging
            channels[i].function.set_default(SRV_Channel::k_GPIO);
        }
#endif
    }

#if AP_FETTEC_ONEWIRE_ENABLED
    fetteconwire_ptr = &fetteconwire;
#endif

#if AP_VOLZ_ENABLED
    volz_ptr = &volz;
#endif

#if AP_SBUSOUTPUT_ENABLED
    sbus_ptr = &sbus;
#endif

#if AP_ROBOTISSERVO_ENABLED
    robotis_ptr = &robotis;
#endif // AP_ROBOTISSERVO_ENABLED

#if HAL_SUPPORT_RCOUT_SERIAL
    blheli_ptr = &blheli;
#endif
}

// SRV_Channels initialization
void SRV_Channels::init(uint32_t motor_mask, AP_HAL::RCOutput::output_mode mode)
{
    // initialize BLHeli late so that all of the masks it might setup don't get trodden on by motor initialization
#if HAL_SUPPORT_RCOUT_SERIAL
    blheli_ptr->init(motor_mask, mode);
#endif
#ifndef HAL_BUILD_AP_PERIPH
    hal.rcout->set_dshot_rate(_singleton->dshot_rate, AP::scheduler().get_loop_rate_hz());
#endif
}

/*
  save adjusted trims
 */
void SRV_Channels::save_trim(void)
{
    for (uint8_t i=0; i<NUM_SERVO_CHANNELS; i++) {
        if (trimmed_mask & (1U<<i)) {
            channels[i].servo_trim.set_and_save(channels[i].servo_trim.get());
        }
    }
    trimmed_mask = 0;
}

void SRV_Channels::setup_failsafe_trim_all_non_motors(void)
{
    for (uint8_t i = 0; i < NUM_SERVO_CHANNELS; i++) {
        if (!SRV_Channel::is_motor(channels[i].get_function())) {
            hal.rcout->set_failsafe_pwm(1U<<channels[i].ch_num, channels[i].servo_trim);
        }
    }
}

/*
  run calc_pwm for all channels
 */
void SRV_Channels::calc_pwm(void)
{
    // slew rate limit functions
    for (slew_list *slew = _slew; slew; slew = slew->next) {
        if (is_positive(slew->max_change)) {
            // treat negative or zero slew rate as disabled
            functions[slew->func].output_scaled = constrain_float(functions[slew->func].output_scaled, slew->last_scaled_output - slew->max_change, slew->last_scaled_output + slew->max_change);
        }
        slew->last_scaled_output = functions[slew->func].output_scaled;
    }

    WITH_SEMAPHORE(_singleton->override_counter_sem);

    for (uint8_t i=0; i<NUM_SERVO_CHANNELS; i++) {
        // check if channel has been locked out for this loop
        // if it has, decrement the loop count for that channel
        if (override_counter[i] == 0) {
            channels[i].set_override(false);
        } else {
            channels[i].set_override(true);
            override_counter[i]--;
        }
        if (channels[i].valid_function()) {
            channels[i].calc_pwm(functions[channels[i].function.get()].output_scaled);
        }
    }
}

// set output value for a specific function channel as a pwm value
void SRV_Channels::set_output_pwm_chan(uint8_t chan, uint16_t value)
{
    if (chan < NUM_SERVO_CHANNELS) {
        channels[chan].set_output_pwm(value);
    }
}

// set output value for a specific function channel as a pwm value with loop based timeout
// timeout_ms of zero will clear override of the channel
// minimum override is 1 MAIN_LOOP
void SRV_Channels::set_output_pwm_chan_timeout(uint8_t chan, uint16_t value, uint16_t timeout_ms)
{
    WITH_SEMAPHORE(_singleton->override_counter_sem);

    if (chan < NUM_SERVO_CHANNELS) {
        const uint32_t loop_period_us = AP::scheduler().get_loop_period_us();
        // round up so any non-zero requested value will result in at least one loop
        const uint32_t loop_count = ((timeout_ms * 1000U) + (loop_period_us - 1U)) / loop_period_us;
        override_counter[chan] = constrain_int32(loop_count, 0, UINT16_MAX);
        channels[chan].set_override(true);
        const bool had_pwm = SRV_Channel::have_pwm_mask & (1U<<chan);
        channels[chan].set_output_pwm(value,true);
        if (!had_pwm) {
            // clear the have PWM mask so the channel will default back to the scaled value when timeout expires
            // this is also cleared by set_output_scaled but that requires it to be re-called as some point
            // after the timeout is applied
            // note that we can't default back to a pre-override PWM value as it is not stored
            // checking had_pwm means the PWM will not change after the timeout, this was the existing behaviour
            SRV_Channel::have_pwm_mask &= ~(1U<<chan);
        }
    }
}

/*
  wrapper around hal.rcout->cork()
 */
void SRV_Channels::cork()
{
    hal.rcout->cork();
}

/*
  wrapper around hal.rcout->push()
 */
void SRV_Channels::push()
{
    hal.rcout->push();

#if AP_VOLZ_ENABLED
    // give volz library a chance to update
    volz_ptr->update();
#endif

#if AP_SBUSOUTPUT_ENABLED
    // give sbus library a chance to update
    sbus_ptr->update();
#endif

#if AP_ROBOTISSERVO_ENABLED
    // give robotis library a chance to update
    robotis_ptr->update();
#endif

#if HAL_SUPPORT_RCOUT_SERIAL
    // give blheli telemetry a chance to update
    blheli_ptr->update_telemetry();
#endif

#if AP_FETTEC_ONEWIRE_ENABLED
    fetteconwire_ptr->update();
#endif

#if AP_KDECAN_ENABLED
    if (AP::kdecan() != nullptr) {
        AP::kdecan()->update();
    }
#endif

#if HAL_ENABLE_DRONECAN_DRIVERS
    // push outputs to CAN
    uint8_t can_num_drivers = AP::can().get_num_drivers();
    for (uint8_t i = 0; i < can_num_drivers; i++) {
        switch (AP::can().get_driver_type(i)) {
            case AP_CAN::Protocol::DroneCAN: {
                AP_DroneCAN *ap_dronecan = AP_DroneCAN::get_dronecan(i);
                if (ap_dronecan == nullptr) {
                    continue;
                }
                ap_dronecan->SRV_push_servos();
                break;
            }
#if HAL_PICCOLO_CAN_ENABLE
            case AP_CAN::Protocol::PiccoloCAN: {
                AP_PiccoloCAN *ap_pcan = AP_PiccoloCAN::get_pcan(i);
                if (ap_pcan == nullptr) {
                    continue;
                }
                ap_pcan->update();
                break;
            }
#endif
            case AP_CAN::Protocol::None:
            default:
                break;
        }
    }
#endif // HAL_NUM_CAN_IFACES
}

void SRV_Channels::zero_rc_outputs()
{
    /* Send an invalid signal to the motors to prevent spinning due to
     * neutral (1500) pwm pulse being cut short.  For that matter,
     * send an invalid signal to all channels to prevent
     * undesired/unexpected behavior
     */
    cork();
    for (uint8_t i=0; i<NUM_SERVO_CHANNELS; i++) {
        hal.rcout->write(i, 0);
    }
    push();
}

/*
  return true if a channel should be available as a GPIO
 */
bool SRV_Channels::is_GPIO(uint8_t channel)
{
    if (channel_function(channel) == SRV_Channel::k_GPIO) {
        return true;
    }
    if (_singleton != nullptr && (_singleton->gpio_mask & (1U<<channel)) != 0) {
        // user has set this channel in SERVO_GPIO_MASK
        return true;
    }
    return false;
}

// Set E - stop
void SRV_Channels::set_emergency_stop(bool state) {
#if HAL_LOGGING_ENABLED
    if (state != emergency_stop) {
        AP_Logger *logger = AP_Logger::get_singleton();
        if (logger && logger->logging_enabled()) {
            logger->Write_Event(state ? LogEvent::MOTORS_EMERGENCY_STOPPED : LogEvent::MOTORS_EMERGENCY_STOP_CLEARED);
        }
    }
#endif
    emergency_stop = state;
}