Unable to read data on arduino serial monitor

MAVLink
21

I’m actually getting some data in my serial connection, when I check if Serial2.available , however,
mavlink_parse_char if statement is returning zero.

I’m attaching my code here

#include <mavlink.h>
//#include <SoftwareSerial.h>

//#define RXpin 0
//#define TXpin 1
//SoftwareSerial SerialMAV(RXpin, TXpin); // sets up serial communication on pins 3 and 2

void setup() {
Serial2.begin(57600); //RXTX from Pixhawk (Port 19,18 Arduino Mega)
Serial.begin(115200); //Main serial port for console output

request_datastream();

}

void loop() {

MavLink_receive();

}

//function called by arduino to read any MAVlink messages sent by serial communication from flight controller to arduino
void MavLink_receive()
{
mavlink_message_t msg;
mavlink_status_t status;

while(Serial2.available())
{Serial.println(“Serial port available”);
uint8_t c= Serial2.read();

//Get new message
if(mavlink_parse_char(MAVLINK_COMM_0, c, &msg, &status))
{

//Handle new message from autopilot
  switch(msg.msgid)
  {

    case MAVLINK_MSG_ID_GPS_RAW_INT:
  {
    mavlink_gps_raw_int_t packet;
    mavlink_msg_gps_raw_int_decode(&msg, &packet);
    
    Serial.print("\nGPS Fix: ");Serial.println(packet.fix_type);
    Serial.print("GPS Latitude: ");Serial.println(packet.lat);
    Serial.print("GPS Longitude: ");Serial.println(packet.lon);
    Serial.print("GPS Speed: ");Serial.println(packet.vel);
    Serial.print("Sats Visible: ");Serial.println(packet.satellites_visible);
   
  }
  break;

  }
}

}
}

void request_datastream() {
//Request Data from Pixhawk
uint8_t _system_id = 255; // id of computer which is sending the command (ground control software has id of 255)
uint8_t _component_id = 2; // seems like it can be any # except the number of what Pixhawk sys_id is
uint8_t _target_system = 1; // Id # of Pixhawk (should be 1)
uint8_t _target_component = 0; // Target component, 0 = all (seems to work with 0 or 1
uint8_t _req_stream_id = MAV_DATA_STREAM_ALL;
uint16_t _req_message_rate = 0x01; //number of times per second to request the data in hex
uint8_t _start_stop = 1; //1 = start, 0 = stop

// STREAMS that can be requested
/*

  • Definitions are in common.h: enum MAV_DATA_STREAM and more importantly at:
    Messages (common) · MAVLink Developer Guide
  • MAV_DATA_STREAM_ALL=0, // Enable all data streams
  • MAV_DATA_STREAM_RAW_SENSORS=1, /* Enable IMU_RAW, GPS_RAW, GPS_STATUS packets.
  • MAV_DATA_STREAM_EXTENDED_STATUS=2, /* Enable GPS_STATUS, CONTROL_STATUS, AUX_STATUS
  • MAV_DATA_STREAM_RC_CHANNELS=3, /* Enable RC_CHANNELS_SCALED, RC_CHANNELS_RAW, SERVO_OUTPUT_RAW
  • MAV_DATA_STREAM_RAW_CONTROLLER=4, /* Enable ATTITUDE_CONTROLLER_OUTPUT, POSITION_CONTROLLER_OUTPUT, NAV_CONTROLLER_OUTPUT.
  • MAV_DATA_STREAM_POSITION=6, /* Enable LOCAL_POSITION, GLOBAL_POSITION/GLOBAL_POSITION_INT messages.
  • MAV_DATA_STREAM_EXTRA1=10, /* Dependent on the autopilot
  • MAV_DATA_STREAM_EXTRA2=11, /* Dependent on the autopilot
  • MAV_DATA_STREAM_EXTRA3=12, /* Dependent on the autopilot
  • MAV_DATA_STREAM_ENUM_END=13,
  • Data in PixHawk available in:
    • Battery, amperage and voltage (SYS_STATUS) in MAV_DATA_STREAM_EXTENDED_STATUS
    • Gyro info (IMU_SCALED) in MAV_DATA_STREAM_EXTRA1
      */

// Initialize the required buffers
mavlink_message_t msg;
uint8_t buf[MAVLINK_MAX_PACKET_LEN];

// Pack the message
mavlink_msg_request_data_stream_pack(_system_id, _component_id, &msg, _target_system, _target_component, _req_stream_id, _req_message_rate, _start_stop);
uint16_t len = mavlink_msg_to_send_buffer(buf, &msg); // Send the message (.write sends as bytes)

Serial2.write(buf, len); //Write data to serial port
}

22

If you’re using MissionPlanner you’re likely using ArduPilot. This forum is for PX4 users. Please ask in discuss.ardupilot.org instead.

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