Send RPM Data from the Arduino to QGroundcontrol using Pixhawk 6x

MAVLink
1

Hi Guys,

I’m trying so send RPM data measured by an Arduino Mega to the Groundcontrolstation via the Mavlink protocol.
Unfortunately I have problems with compiling the code in the Arduino IDE.
The errors I get are:
Compilation error: ‘Mavlink’ was not declared in this scope
error: ‘mavlink_msg_efi_status_pack’ was not declared in this scope
mavlink_msg_efi_status_pack(1, 200, &msg, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
note: suggested alternative: ‘mavlink_msg_gps_status_pack’
mavlink_msg_efi_status_pack(1, 200, &msg, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
^~~~~~~~~~~~~~~~~~~~~~~~~~~

this is my code:

#include <mavlink.h>

// RPM Sensor
const int signalPin = 2; // Der Pin, an dem das Signal angeschlossen ist
volatile unsigned long startMicros = 0;
volatile bool firstEdgeDetected = false;

void setup() {
  Serial.begin(57600); // Initialisierung der seriellen Kommunikation
  pinMode(signalPin, INPUT); // Setzen Sie den Pin als Eingang
  attachInterrupt(digitalPinToInterrupt(signalPin), handleInterrupt, RISING); // Interrupt für steigende Flanken aktivieren
  Mavlink.begin(Serial); // Initialisieren Sie die Mavlink-Kommunikation
}

void loop() {
  // Hier können Sie andere Aufgaben ausführen, wenn nötig
  delay(2000); // Warten Sie 2 Sekunden zwischen den Mavlink-Nachrichten
  sendRPMFrequency(); // Senden Sie die RPM-Frequenz per Mavlink
}

void handleInterrupt() {
  if (!firstEdgeDetected) {
    startMicros = micros(); // Zeitpunkt der ersten steigenden Flanke speichern
    firstEdgeDetected = true;
  } else {
    unsigned long endMicros = micros(); // Zeitpunkt der zweiten steigenden Flanke speichern
    firstEdgeDetected = false;

    unsigned long timeBetweenEdges = endMicros - startMicros; // Zeit zwischen den Flanken in Mikrosekunden
    float frequency = 1000000.0 / timeBetweenEdges; // Frequenzberechnung (in Hertz)
    Serial.print("Frequenz: ");
    Serial.print(frequency);
    Serial.println(" Hz");
  }
}

void sendRPMFrequency() {
  // Erstellen Sie eine EFI_STATUS Mavlink-Nachricht
  mavlink_message_t msg;
  mavlink_msg_efi_status_pack(1, 200, &msg, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

  // Senden Sie die Mavlink-Nachricht
  uint8_t buf[MAVLINK_MAX_PACKET_LEN];
  uint16_t len = mavlink_msg_to_send_buffer(buf, &msg);
  Serial.write(buf, len);
}

Could you help me please?

2

Check your mavlink include and whether the EFI_STATUS message is actually in there.

1 Like
3

Sorry but I did not get your point, the mavlink.h library is included and in the right folder
what else can I do?

4

I think I have found the problem:

  1. my library mavlink.h wasn’t installed right
  2. my library doesn’t include the efi message library in the common folder

But how to solve this issue?

5

Where do you get the mavlink library from?

Maybe you need to regenerate the header files as explained in Generate MAVLink Libraries · MAVLink Developer Guide and then replace the existing header files with the new ones.

1 Like
7

Update: I downloaded a more updated library version mavlink/c_library_v2: Official reference C / C++ library for the v2 protocol (github.com)

There is the wanted file mavlink_msg_efi_status.h which was missing in the previous library that I used