Tutorial One: Hello INDI

This tutorial demonstrates how to create the most basic INDI device driver. It’s a minimal implementation that only provides the essential functionality required by the INDI protocol.

What You’ll Learn

• How to create a basic INDI device driver
• The minimal required functions for an INDI driver
• How to handle connect and disconnect operations

Source Code

simpledevice.h

/*
INDI Developers Manual
   Tutorial #1

   "Hello INDI"

   We construct a most basic (and useless) device driver to illustate INDI.

   Refer to README which contains instruction on how to build this driver and use it
   with an INDI-compatible client.

*/

/** \file simpledevice.h
    \brief Construct a basic INDI device with only one property to connect and disconnect.
    \author Jasem Mutlaq

    \example simpledevice.h
    A very minimal device! It also allows you to connect/disconnect and performs no other functions.
*/

#pragma once

#include "defaultdevice.h"

class SimpleDevice : public INDI::DefaultDevice
{
    public:
        SimpleDevice() = default;

    protected:
        bool Connect() override;
        bool Disconnect() override;
        const char *getDefaultName() override;
};

simpledevice.cpp

/*
INDI Developers Manual
   Tutorial #1

   "Hello INDI"

   We construct a most basic (and useless) device driver to illustrate INDI.

   Refer to README which contains instruction on how to build this driver and use it
   with an INDI-compatible client.

*/

/** \file simpledevice.cpp
    \brief Construct a basic INDI device with only one property to connect and disconnect.
    \author Jasem Mutlaq

    \example simpledevice.cpp
    A very minimal device! It also allows you to connect/disconnect and performs no other functions.
*/

#include "simpledevice.h"

#include <memory>

std::unique_ptr<SimpleDevice> simpleDevice(new SimpleDevice());

/**************************************************************************************
** Client is asking us to establish connection to the device
***************************************************************************************/
bool SimpleDevice::Connect()
{
    LOG_INFO("Simple device connected successfully!");
    return true;
}

/**************************************************************************************
** Client is asking us to terminate connection to the device
***************************************************************************************/
bool SimpleDevice::Disconnect()
{
    LOG_INFO("Simple device disconnected successfully!");
    return true;
}

/**************************************************************************************
** INDI is asking us for our default device name
***************************************************************************************/
const char *SimpleDevice::getDefaultName()
{
    return "Simple Device";
}

Code Explanation

This driver is the simplest possible INDI device. Let’s break down what’s happening:

1. Class Definition: The SimpleDevice class inherits from INDI::DefaultDevice, which provides the basic functionality required by all INDI devices.

2. Required Overrides:

   • Connect(): Called when a client requests to connect to the device. In a real driver, this would establish a connection to the physical hardware.
   • Disconnect(): Called when a client requests to disconnect from the device. In a real driver, this would close the connection to the physical hardware.
   • getDefaultName(): Returns the default name of the device, which is used by clients to identify it.

3. Device Instance: The line std::unique_ptr<SimpleDevice> simpleDevice(new SimpleDevice()); creates a global instance of the device. This is required for the INDI server to find and use the driver.

Running the Tutorial

To run this tutorial:

1. Build the tutorial using CMake:

   cd /path/to/indi/build
   make
   

2. Run the INDI server with the tutorial driver:

   indiserver -v ./tutorial_one
   

3. Connect to the server using an INDI client (like KStars/EKOS or INDI Control Panel).

4. You should see the “Simple Device” in the client, and you can connect to it.

Next Steps

This tutorial demonstrates the absolute minimum required for an INDI driver. In Tutorial Two, we’ll build on this foundation to create a simple telescope simulator with more functionality.