ardupilot/libraries/AP_SerialManager/AP_SerialManager.cpp

/*
   Please contribute your ideas! See http://dev.ardupilot.org for details

   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/>.
 */
/*
  SerialManager allows defining the protocol and baud rates for the available
  serial ports and provides helper functions so objects (like a gimbal) can
  find which serial port they should use
 */

#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#include "AP_SerialManager.h"

extern const AP_HAL::HAL& hal;

#ifdef HAL_SERIAL5_PROTOCOL
#define SERIAL5_PROTOCOL HAL_SERIAL5_PROTOCOL
#define SERIAL5_BAUD HAL_SERIAL5_BAUD
#else
#define SERIAL5_PROTOCOL SerialProtocol_None
#define SERIAL5_BAUD AP_SERIALMANAGER_MAVLINK_BAUD/1000
#endif

#ifdef HAL_SERIAL2_PROTOCOL
#define SERIAL2_PROTOCOL_DEFAULT HAL_SERIAL2_PROTOCOL
#else
#define SERIAL2_PROTOCOL_DEFAULT SerialProtocol_MAVLink
#endif

#ifndef HAL_SERIAL6_PROTOCOL
#define SERIAL6_PROTOCOL SerialProtocol_None
#define SERIAL6_BAUD AP_SERIALMANAGER_MAVLINK_BAUD/1000
#endif

const AP_Param::GroupInfo AP_SerialManager::var_info[] = {
    // @Param: 0_BAUD
    // @DisplayName: Serial0 baud rate
    // @Description: The baud rate used on the USB console. Most stm32-based boards can support rates of up to 1500. If you setup a rate you cannot support and then can't connect to your board you should load a firmware from a different vehicle type. That will reset all your parameters to defaults.
    // @Values: 1:1200,2:2400,4:4800,9:9600,19:19200,38:38400,57:57600,111:111100,115:115200,256:256000,460:460800,500:500000,921:921600,1500:1500000
    // @User: Standard
    AP_GROUPINFO("0_BAUD",  0, AP_SerialManager, state[0].baud, AP_SERIALMANAGER_CONSOLE_BAUD/1000),

    // @Param: 0_PROTOCOL
    // @DisplayName: Console protocol selection
    // @Description: Control what protocol to use on the console. 
    // @Values: 1:MAVlink1, 2:MAVLink2
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("0_PROTOCOL",  11, AP_SerialManager, state[0].protocol, SerialProtocol_MAVLink2),
    
    // @Param: 1_PROTOCOL
    // @DisplayName: Telem1 protocol selection
    // @Description: Control what protocol to use on the Telem1 port. Note that the Frsky options require external converter hardware. See the wiki for details.
    // @Values: -1:None, 1:MAVLink1, 2:MAVLink2, 3:Frsky D, 4:Frsky SPort, 5:GPS, 7:Alexmos Gimbal Serial, 8:SToRM32 Gimbal Serial, 9:Rangefinder, 10:FrSky SPort Passthrough (OpenTX), 11:Lidar360, 13:Beacon, 14:Volz servo out, 15:SBus servo out, 16:ESC Telemetry, 17:Devo Telemetry, 18:OpticalFlow, 19:RobotisServo, 20:NMEA Output, 21:WindVane
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("1_PROTOCOL",  1, AP_SerialManager, state[1].protocol, SerialProtocol_MAVLink),

    // @Param: 1_BAUD
    // @DisplayName: Telem1 Baud Rate
    // @Description: The baud rate used on the Telem1 port. Most stm32-based boards can support rates of up to 1500. If you setup a rate you cannot support and then can't connect to your board you should load a firmware from a different vehicle type. That will reset all your parameters to defaults.
    // @Values: 1:1200,2:2400,4:4800,9:9600,19:19200,38:38400,57:57600,111:111100,115:115200,256:256000,500:500000,921:921600,1500:1500000
    // @User: Standard
    AP_GROUPINFO("1_BAUD", 2, AP_SerialManager, state[1].baud, AP_SERIALMANAGER_MAVLINK_BAUD/1000),

    // @Param: 2_PROTOCOL
    // @DisplayName: Telemetry 2 protocol selection
    // @Description: Control what protocol to use on the Telem2 port. Note that the Frsky options require external converter hardware. See the wiki for details.
    // @Values: -1:None, 1:MAVLink1, 2:MAVLink2, 3:Frsky D, 4:Frsky SPort, 5:GPS, 7:Alexmos Gimbal Serial, 8:SToRM32 Gimbal Serial, 9:Rangefinder, 10:FrSky SPort Passthrough (OpenTX), 11:Lidar360, 13:Beacon, 14:Volz servo out, 15:SBus servo out, 16:ESC Telemetry, 17:Devo Telemetry, 18:OpticalFlow, 19:RobotisServo, 20:NMEA Output, 21:WindVane
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("2_PROTOCOL",  3, AP_SerialManager, state[2].protocol, SERIAL2_PROTOCOL_DEFAULT),

    // @Param: 2_BAUD
    // @DisplayName: Telemetry 2 Baud Rate
    // @Description: The baud rate of the Telem2 port. Most stm32-based boards can support rates of up to 1500. If you setup a rate you cannot support and then can't connect to your board you should load a firmware from a different vehicle type. That will reset all your parameters to defaults.
    // @Values: 1:1200,2:2400,4:4800,9:9600,19:19200,38:38400,57:57600,111:111100,115:115200,256:256000,500:500000,921:921600,1500:1500000
    // @User: Standard
    AP_GROUPINFO("2_BAUD", 4, AP_SerialManager, state[2].baud, AP_SERIALMANAGER_MAVLINK_BAUD/1000),

    // @Param: 3_PROTOCOL
    // @DisplayName: Serial 3 (GPS) protocol selection
    // @Description: Control what protocol Serial 3 (GPS) should be used for. Note that the Frsky options require external converter hardware. See the wiki for details.
    // @Values: -1:None, 1:MAVLink1, 2:MAVLink2, 3:Frsky D, 4:Frsky SPort, 5:GPS, 7:Alexmos Gimbal Serial, 8:SToRM32 Gimbal Serial, 9:Rangefinder, 10:FrSky SPort Passthrough (OpenTX), 11:Lidar360, 13:Beacon, 14:Volz servo out, 15:SBus servo out, 16:ESC Telemetry, 17:Devo Telemetry, 18:OpticalFlow, 19:RobotisServo, 20:NMEA Output, 21:WindVane
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("3_PROTOCOL",  5, AP_SerialManager, state[3].protocol, SerialProtocol_GPS),

    // @Param: 3_BAUD
    // @DisplayName: Serial 3 (GPS) Baud Rate
    // @Description: The baud rate used for the Serial 3 (GPS). Most stm32-based boards can support rates of up to 1500. If you setup a rate you cannot support and then can't connect to your board you should load a firmware from a different vehicle type. That will reset all your parameters to defaults.
    // @Values: 1:1200,2:2400,4:4800,9:9600,19:19200,38:38400,57:57600,111:111100,115:115200,256:256000,500:500000,921:921600,1500:1500000
    // @User: Standard
    AP_GROUPINFO("3_BAUD", 6, AP_SerialManager, state[3].baud, AP_SERIALMANAGER_GPS_BAUD/1000),

    // @Param: 4_PROTOCOL
    // @DisplayName: Serial4 protocol selection
    // @Description: Control what protocol Serial4 port should be used for. Note that the Frsky options require external converter hardware. See the wiki for details.
    // @Values: -1:None, 1:MAVLink1, 2:MAVLink2, 3:Frsky D, 4:Frsky SPort, 5:GPS, 7:Alexmos Gimbal Serial, 8:SToRM32 Gimbal Serial, 9:Rangefinder, 10:FrSky SPort Passthrough (OpenTX), 11:Lidar360, 13:Beacon, 14:Volz servo out, 15:SBus servo out, 16:ESC Telemetry, 17:Devo Telemetry, 18:OpticalFlow, 19:RobotisServo, 20:NMEA Output, 21:WindVane
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("4_PROTOCOL",  7, AP_SerialManager, state[4].protocol, SerialProtocol_GPS),

    // @Param: 4_BAUD
    // @DisplayName: Serial 4 Baud Rate
    // @Description: The baud rate used for Serial4. Most stm32-based boards can support rates of up to 1500. If you setup a rate you cannot support and then can't connect to your board you should load a firmware from a different vehicle type. That will reset all your parameters to defaults.
    // @Values: 1:1200,2:2400,4:4800,9:9600,19:19200,38:38400,57:57600,111:111100,115:115200,256:256000,500:500000,921:921600,1500:1500000
    // @User: Standard
    AP_GROUPINFO("4_BAUD", 8, AP_SerialManager, state[4].baud, AP_SERIALMANAGER_GPS_BAUD/1000),

    // @Param: 5_PROTOCOL
    // @DisplayName: Serial5 protocol selection
    // @Description: Control what protocol Serial5 port should be used for. Note that the Frsky options require external converter hardware. See the wiki for details.
    // @Values: -1:None, 1:MAVLink1, 2:MAVLink2, 3:Frsky D, 4:Frsky SPort, 5:GPS, 7:Alexmos Gimbal Serial, 8:SToRM32 Gimbal Serial, 9:Rangefinder, 10:FrSky SPort Passthrough (OpenTX), 11:Lidar360, 13:Beacon, 14:Volz servo out, 15:SBus servo out, 16:ESC Telemetry, 17:Devo Telemetry, 18:OpticalFlow, 19:RobotisServo, 20:NMEA Output, 21:WindVane
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("5_PROTOCOL",  9, AP_SerialManager, state[5].protocol, SERIAL5_PROTOCOL),

    // @Param: 5_BAUD
    // @DisplayName: Serial 5 Baud Rate
    // @Description: The baud rate used for Serial5. Most stm32-based boards can support rates of up to 1500. If you setup a rate you cannot support and then can't connect to your board you should load a firmware from a different vehicle type. That will reset all your parameters to defaults.
    // @Values: 1:1200,2:2400,4:4800,9:9600,19:19200,38:38400,57:57600,111:111100,115:115200,256:256000,500:500000,921:921600,1500:1500000
    // @User: Standard
    AP_GROUPINFO("5_BAUD", 10, AP_SerialManager, state[5].baud, SERIAL5_BAUD),

    // index 11 used by 0_PROTOCOL
        
    // @Param: 6_PROTOCOL
    // @DisplayName: Serial6 protocol selection
    // @Description: Control what protocol Serial6 port should be used for. Note that the Frsky options require external converter hardware. See the wiki for details.
    // @Values: -1:None, 1:MAVLink1, 2:MAVLink2, 3:Frsky D, 4:Frsky SPort, 5:GPS, 7:Alexmos Gimbal Serial, 8:SToRM32 Gimbal Serial, 9:Rangefinder, 10:FrSky SPort Passthrough (OpenTX), 11:Lidar360, 13:Beacon, 14:Volz servo out, 15:SBus servo out, 16:ESC Telemetry, 17:Devo Telemetry, 18:OpticalFlow, 19:RobotisServo, 20:NMEA Output, 21:WindVane
    // @User: Standard
    // @RebootRequired: True
    AP_GROUPINFO("6_PROTOCOL",  12, AP_SerialManager, state[6].protocol, SERIAL6_PROTOCOL),

    // @Param: 6_BAUD
    // @DisplayName: Serial 6 Baud Rate
    // @Description: The baud rate used for Serial6. Most stm32-based boards can support rates of up to 1500. If you setup a rate you cannot support and then can't connect to your board you should load a firmware from a different vehicle type. That will reset all your parameters to defaults.
    // @Values: 1:1200,2:2400,4:4800,9:9600,19:19200,38:38400,57:57600,111:111100,115:115200,256:256000,500:500000,921:921600,1500:1500000
    // @User: Standard
    AP_GROUPINFO("6_BAUD", 13, AP_SerialManager, state[6].baud, SERIAL6_BAUD),

    // @Param: 1_OPTIONS
    // @DisplayName: Telem1 options
    // @Description: Control over UART options. The InvertRX option controls invert of the receive pin. The InvertTX option controls invert of the transmit pin. The HalfDuplex option controls half-duplex (onewire) mode, where both transmit and receive is done on the transmit wire. The Swap option allows the RX and TX pins to be swapped on STM32F7 based boards.
    // @Bitmask: 0:InvertRX, 1:InvertTX, 2:HalfDuplex, 4:Swap
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("1_OPTIONS",  14, AP_SerialManager, state[1].options, 0),

    // @Param: 2_OPTIONS
    // @DisplayName: Telem2 options
    // @Description: Control over UART options. The InvertRX option controls invert of the receive pin. The InvertTX option controls invert of the transmit pin. The HalfDuplex option controls half-duplex (onewire) mode, where both transmit and receive is done on the transmit wire.
    // @Bitmask: 0:InvertRX, 1:InvertTX, 2:HalfDuplex, 4:Swap
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("2_OPTIONS",  15, AP_SerialManager, state[2].options, 0),

    // @Param: 3_OPTIONS
    // @DisplayName: Serial3 options
    // @Description: Control over UART options. The InvertRX option controls invert of the receive pin. The InvertTX option controls invert of the transmit pin. The HalfDuplex option controls half-duplex (onewire) mode, where both transmit and receive is done on the transmit wire.
    // @Bitmask: 0:InvertRX, 1:InvertTX, 2:HalfDuplex, 4:Swap
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("3_OPTIONS",  16, AP_SerialManager, state[3].options, 0),

    // @Param: 4_OPTIONS
    // @DisplayName: Serial4 options
    // @Description: Control over UART options. The InvertRX option controls invert of the receive pin. The InvertTX option controls invert of the transmit pin. The HalfDuplex option controls half-duplex (onewire) mode, where both transmit and receive is done on the transmit wire.
    // @Bitmask: 0:InvertRX, 1:InvertTX, 2:HalfDuplex, 4:Swap
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("4_OPTIONS",  17, AP_SerialManager, state[4].options, 0),

    // @Param: 5_OPTIONS
    // @DisplayName: Serial5 options
    // @Description: Control over UART options. The InvertRX option controls invert of the receive pin. The InvertTX option controls invert of the transmit pin. The HalfDuplex option controls half-duplex (onewire) mode, where both transmit and receive is done on the transmit wire.
    // @Bitmask: 0:InvertRX, 1:InvertTX, 2:HalfDuplex, 4:Swap
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("5_OPTIONS",  18, AP_SerialManager, state[5].options, 0),

    // @Param: 6_OPTIONS
    // @DisplayName: Serial6 options
    // @Description: Control over UART options. The InvertRX option controls invert of the receive pin. The InvertTX option controls invert of the transmit pin. The HalfDuplex option controls half-duplex (onewire) mode, where both transmit and receive is done on the transmit wire.
    // @Bitmask: 0:InvertRX, 1:InvertTX, 2:HalfDuplex, 4:Swap
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("6_OPTIONS",  19, AP_SerialManager, state[6].options, 0),

    // @Param: _PASS1
    // @DisplayName: Serial passthru first port
    // @Description: This sets one side of pass-through between two serial ports. Once both sides are set then all data received on either port will be passed to the other port
    // @Values: -1:Disabled,0:Serial0,1:Serial1,2:Serial2,3:Serial3,4:Serial4,5:Serial5,6:Serial6
    // @User: Advanced
    AP_GROUPINFO("_PASS1",  20, AP_SerialManager, passthru_port1, 0),

    // @Param: _PASS2
    // @DisplayName: Serial passthru second port
    // @Description: This sets one side of pass-through between two serial ports. Once both sides are set then all data received on either port will be passed to the other port
    // @Values: -1:Disabled,0:Serial0,1:Serial1,2:Serial2,3:Serial3,4:Serial4,5:Serial5,6:Serial6
    // @User: Advanced
    AP_GROUPINFO("_PASS2",  21, AP_SerialManager, passthru_port2, -1),

    // @Param: _PASSTIMO
    // @DisplayName: Serial passthru timeout
    // @Description: This sets a timeout for serial pass-through in seconds. When the pass-through is enabled by setting the SERIAL_PASS1 and SERIAL_PASS2 parameters then it remains in effect until no data comes from the first port for SERIAL_PASSTIMO seconds. This allows the port to revent to its normal usage (such as MAVLink connection to a GCS) when it is no longer needed. A value of 0 means no timeout.
    // @Range: 0 120
    // @Units: s
    // @User: Advanced
    AP_GROUPINFO("_PASSTIMO",  22, AP_SerialManager, passthru_timeout, 15),
    
    AP_GROUPEND
};

// singleton instance
AP_SerialManager *AP_SerialManager::_singleton;

// Constructor
AP_SerialManager::AP_SerialManager()
{
    _singleton = this;
    // setup parameter defaults
    AP_Param::setup_object_defaults(this, var_info);
}

// init_console - initialise console at default baud rate
void AP_SerialManager::init_console()
{
    // initialise console immediately at default size and baud
    state[0].uart = hal.uartA;  // serial0, uartA, always console
    state[0].uart->begin(AP_SERIALMANAGER_CONSOLE_BAUD,
                         AP_SERIALMANAGER_CONSOLE_BUFSIZE_RX,
                         AP_SERIALMANAGER_CONSOLE_BUFSIZE_TX);
}

extern bool g_nsh_should_exit;

// init - // init - initialise serial ports
void AP_SerialManager::init()
{
    // always reset passthru port2 on boot
    passthru_port2.set_and_save_ifchanged(-1);

    // initialise pointers to serial ports
    state[1].uart = hal.uartC;  // serial1, uartC, normally telem1
    state[2].uart = hal.uartD;  // serial2, uartD, normally telem2
    state[3].uart = hal.uartB;  // serial3, uartB, normally 1st GPS
    state[4].uart = hal.uartE;  // serial4, uartE, normally 2nd GPS
    state[5].uart = hal.uartF;  // serial5
    state[6].uart = hal.uartG;  // serial6

    if (state[0].uart == nullptr) {
        init_console();
    }
    
    // initialise serial ports
    for (uint8_t i=1; i<SERIALMANAGER_NUM_PORTS; i++) {

        if (state[i].uart != nullptr) {

            // see if special options have been requested
            if (state[i].protocol != SerialProtocol_None && state[i].options) {
                set_options(i);
            }

            switch (state[i].protocol) {
                case SerialProtocol_None:
                    break;
                case SerialProtocol_Console:
                case SerialProtocol_MAVLink:
                case SerialProtocol_MAVLink2:
                    state[i].uart->begin(map_baudrate(state[i].baud), 
                                         AP_SERIALMANAGER_MAVLINK_BUFSIZE_RX,
                                         AP_SERIALMANAGER_MAVLINK_BUFSIZE_TX);
                    break;
                case SerialProtocol_FrSky_D:
                    // Note baudrate is hardcoded to 9600
                    state[i].baud = AP_SERIALMANAGER_FRSKY_D_BAUD/1000; // update baud param in case user looks at it
                    // begin is handled by AP_Frsky_telem library
                    break;
                case SerialProtocol_FrSky_SPort:
                case SerialProtocol_FrSky_SPort_Passthrough:
                    // Note baudrate is hardcoded to 57600
                    state[i].baud = AP_SERIALMANAGER_FRSKY_SPORT_BAUD/1000; // update baud param in case user looks at it
                    // begin is handled by AP_Frsky_telem library
                    break;
                case SerialProtocol_GPS:
                case SerialProtocol_GPS2:
                    state[i].uart->begin(map_baudrate(state[i].baud), 
                                         AP_SERIALMANAGER_GPS_BUFSIZE_RX,
                                         AP_SERIALMANAGER_GPS_BUFSIZE_TX);
                    break;
                case SerialProtocol_AlexMos:
                    // Note baudrate is hardcoded to 115200
                    state[i].baud = AP_SERIALMANAGER_ALEXMOS_BAUD / 1000;   // update baud param in case user looks at it
                    state[i].uart->begin(AP_SERIALMANAGER_ALEXMOS_BAUD,
                                         AP_SERIALMANAGER_ALEXMOS_BUFSIZE_RX,
                                         AP_SERIALMANAGER_ALEXMOS_BUFSIZE_TX);
                    break;
                case SerialProtocol_SToRM32:
                    // Note baudrate is hardcoded to 115200
                    state[i].baud = AP_SERIALMANAGER_SToRM32_BAUD / 1000;   // update baud param in case user looks at it
                    state[i].uart->begin(map_baudrate(state[i].baud),
                                         AP_SERIALMANAGER_SToRM32_BUFSIZE_RX,
                                         AP_SERIALMANAGER_SToRM32_BUFSIZE_TX);
                    break;
                case SerialProtocol_Aerotenna_uLanding:
                    state[i].protocol.set_and_save(SerialProtocol_Rangefinder);
                    break;
                case SerialProtocol_Volz:
                                    // Note baudrate is hardcoded to 115200
                                    state[i].baud = AP_SERIALMANAGER_VOLZ_BAUD;   // update baud param in case user looks at it
                                    state[i].uart->begin(map_baudrate(state[i].baud),
                                    		AP_SERIALMANAGER_VOLZ_BUFSIZE_RX,
											AP_SERIALMANAGER_VOLZ_BUFSIZE_TX);
                                    state[i].uart->set_unbuffered_writes(true);
                                    state[i].uart->set_flow_control(AP_HAL::UARTDriver::FLOW_CONTROL_DISABLE);
                                    break;
                case SerialProtocol_Sbus1:
                    state[i].baud = AP_SERIALMANAGER_SBUS1_BAUD / 1000;   // update baud param in case user looks at it
                    state[i].uart->begin(map_baudrate(state[i].baud),
                                         AP_SERIALMANAGER_SBUS1_BUFSIZE_RX,
                                         AP_SERIALMANAGER_SBUS1_BUFSIZE_TX);
                    state[i].uart->configure_parity(2);    // enable even parity
                    state[i].uart->set_stop_bits(2);
                    state[i].uart->set_unbuffered_writes(true);
                    state[i].uart->set_flow_control(AP_HAL::UARTDriver::FLOW_CONTROL_DISABLE);
                    break;

                case SerialProtocol_ESCTelemetry:
                    // ESC telemetry protocol from BLHeli32 ESCs. Note that baudrate is hardcoded to 115200
                    state[i].baud = 115200;
                    state[i].uart->begin(map_baudrate(state[i].baud), 30, 30);
                    state[i].uart->set_flow_control(AP_HAL::UARTDriver::FLOW_CONTROL_DISABLE);
                    break;

                case SerialProtocol_Robotis:
                    state[i].uart->begin(map_baudrate(state[i].baud),
                                         AP_SERIALMANAGER_ROBOTIS_BUFSIZE_RX,
                                         AP_SERIALMANAGER_ROBOTIS_BUFSIZE_TX);
                    state[i].uart->set_unbuffered_writes(true);
                    state[i].uart->set_flow_control(AP_HAL::UARTDriver::FLOW_CONTROL_DISABLE);
                    break;

                default:
                    state[i].uart->begin(map_baudrate(state[i].baud));
                    break;
            }
        }
    }
}


const AP_SerialManager::UARTState *AP_SerialManager::find_protocol_instance(enum SerialProtocol protocol, uint8_t instance) const
{
    uint8_t found_instance = 0;

    // search for matching protocol
    for(uint8_t i=0; i<SERIALMANAGER_NUM_PORTS; i++) {
        if (protocol_match(protocol, (enum SerialProtocol)state[i].protocol.get())) {
            if (found_instance == instance) {
                return &state[i];
            }
            found_instance++;
        }
    }

    // if we got this far we did not find the uart
    return nullptr;
}

// find_serial - searches available serial ports for the first instance that allows the given protocol
//  instance should be zero if searching for the first instance, 1 for the second, etc
//  returns uart on success, nullptr if a serial port cannot be found
AP_HAL::UARTDriver *AP_SerialManager::find_serial(enum SerialProtocol protocol, uint8_t instance) const
{
    const struct UARTState *_state = find_protocol_instance(protocol, instance);
    if (_state == nullptr) {
        return nullptr;
    }
    return _state->uart;
}

// find_baudrate - searches available serial ports for the first instance that allows the given protocol
//  instance should be zero if searching for the first instance, 1 for the second, etc
//  returns baudrate on success, 0 if a serial port cannot be found
uint32_t AP_SerialManager::find_baudrate(enum SerialProtocol protocol, uint8_t instance) const
{
    const struct UARTState *_state = find_protocol_instance(protocol, instance);
    if (_state == nullptr) {
        return 0;
    }
    return map_baudrate(_state->baud);
}

// get_mavlink_channel - provides the mavlink channel associated with a given protocol
//  instance should be zero if searching for the first instance, 1 for the second, etc
//  returns true if a channel is found, false if not
bool AP_SerialManager::get_mavlink_channel(enum SerialProtocol protocol, uint8_t instance, mavlink_channel_t &mav_chan) const
{
    // check for MAVLink
    if (protocol_match(protocol, SerialProtocol_MAVLink)) {
        if (instance < MAVLINK_COMM_NUM_BUFFERS) {
            mav_chan = (mavlink_channel_t)(MAVLINK_COMM_0 + instance);
            return true;
        }
    }
    // report failure
    return false;
}


// get_mavlink_protocol - provides the specific MAVLink protocol for a
// given channel, or SerialProtocol_None if not found
AP_SerialManager::SerialProtocol AP_SerialManager::get_mavlink_protocol(mavlink_channel_t mav_chan) const
{
    uint8_t instance = 0;
    uint8_t chan_idx = (uint8_t)(mav_chan - MAVLINK_COMM_0);
    for (uint8_t i=0; i<SERIALMANAGER_NUM_PORTS; i++) {
        if (state[i].protocol == SerialProtocol_MAVLink ||
            state[i].protocol == SerialProtocol_MAVLink2) {
            if (instance == chan_idx) {
                return (SerialProtocol)state[i].protocol.get();
            }
            instance++;
        }
    }
    return SerialProtocol_None;
}

// get_serial_by_id - gets serial by serial id
AP_HAL::UARTDriver *AP_SerialManager::get_serial_by_id(uint8_t id)
{
    if (id < SERIALMANAGER_NUM_PORTS) {
        return state[id].uart;
    }
    return nullptr;
}

// set_blocking_writes_all - sets block_writes on or off for all serial channels
void AP_SerialManager::set_blocking_writes_all(bool blocking)
{
    // set block_writes for all initialised serial ports
    for (uint8_t i=0; i<SERIALMANAGER_NUM_PORTS; i++) {
        if (state[i].uart != nullptr) {
            state[i].uart->set_blocking_writes(blocking);
        }
    }
}

/*
 *  map from a 16 bit EEPROM baud rate to a real baud rate.  For
 *  stm32-based boards we can do 1.5MBit, although 921600 is more
 *  reliable.
 */
uint32_t AP_SerialManager::map_baudrate(int32_t rate) const
{
    if (rate <= 0) {
        rate = 57;
    }
    switch (rate) {
    case 1:    return 1200;
    case 2:    return 2400;
    case 4:    return 4800;
    case 9:    return 9600;
    case 19:   return 19200;
    case 38:   return 38400;
    case 57:   return 57600;
    case 100:  return 100000;
    case 111:  return 111100;
    case 115:  return 115200;
    case 230:  return 230400;
    case 256:  return 256000;
    case 460:  return 460800;
    case 500:  return 500000;
    case 921:  return 921600;
    case 1500:  return 1500000;
    }

    if (rate > 2000) {
        // assume it is a direct baudrate. This allows for users to
        // set an exact baudrate as long as it is over 2000 baud
        return (uint32_t)rate;
    }

    // otherwise allow any other kbaud rate
    return rate*1000;
}

// protocol_match - returns true if the protocols match
bool AP_SerialManager::protocol_match(enum SerialProtocol protocol1, enum SerialProtocol protocol2) const
{
    // check for obvious match
    if (protocol1 == protocol2) {
        return true;
    }

    // mavlink match
    if (((protocol1 == SerialProtocol_MAVLink) || (protocol1 == SerialProtocol_MAVLink2)) &&
        ((protocol2 == SerialProtocol_MAVLink) || (protocol2 == SerialProtocol_MAVLink2))) {
        return true;
    }

    // gps match
    if (((protocol1 == SerialProtocol_GPS) || (protocol1 == SerialProtocol_GPS2)) &&
        ((protocol2 == SerialProtocol_GPS) || (protocol2 == SerialProtocol_GPS2))) {
        return true;
    }

    return false;
}

// setup any special options
void AP_SerialManager::set_options(uint8_t i)
{
    struct UARTState &opt = state[i];
    // pass through to HAL
    if (!opt.uart->set_options(opt.options)) {
        hal.console->printf("Unable to setup options for Serial%u\n", i);
    }
}

// get the passthru ports if enabled
bool AP_SerialManager::get_passthru(AP_HAL::UARTDriver *&port1, AP_HAL::UARTDriver *&port2, uint8_t &timeout_s) const
{
    if (passthru_port2 < 0 ||
        passthru_port2 >= SERIALMANAGER_NUM_PORTS ||
        passthru_port1 < 0 ||
        passthru_port1 >= SERIALMANAGER_NUM_PORTS) {
        return false;
    }
    port1 = state[passthru_port1].uart;
    port2 = state[passthru_port2].uart;
    timeout_s = MAX(passthru_timeout, 0);
    return true;
}

// disable passthru by settings SERIAL_PASS2 to -1
void AP_SerialManager::disable_passthru(void)
{
    passthru_port2.set_and_notify(-1);
}


namespace AP {

AP_SerialManager &serialmanager()
{
    return *AP_SerialManager::get_singleton();
}

}