B4A Library DJI Drones

DJI Drones are very popular and advanced drones. DJI provides an Android app that is used during flights to control the drone.
The Android device connects to the remote controller with a USB cable (USB debug mode should be enabled).

DJI are also providing a feature-rich SDK that allows us, developers, to create alternative applications to control the drone. It is quite amazing to be able to easily program a drone to do all kinds of sophisticated tasks.

The following video is an example created with B4A and the DJI library. On the left side you can see the drone camera feed and various parameters. On the right side there is a standard Google Map. Touching on a point in the map starts a hotspot mission. The drone will rotate automatically around the spot.


How to use

1. Register with DJI: https://developer.dji.com/ and create an app in the User Center page. You will see an App Key that you need to add to the manifest editor.
The bundle identifier must match your app package name.
2. Add this code to the manifest editor:

AddReplacement($DJI_KEY$, XXXXXXXXX)
CreateResourceFromFile(Macro, DJI.DJI)

Replace XXXXXXXXXX with your App key.
3. Add to the main activity code:

#BridgeLogger: true
#MultiDex: true
#AdditionalJar: dji-sdk-provided-4.15, ReferenceOnly

4. You might need to install a few components with B4A Sdk Manager.
5 Initialize the SDK when the application starts. The RegisteredResult event will be raised. If successful then call sdk.StartConnectionToProduct to start a connection.
6. The ProductConnected event will be raised. If AircraftData is not Null then you are good to go and can initialize the DJIAircraft object and the other features (see how it is done in the example).
7 Most of the operations are asynchronous. They are built to work with the Wait For keyword.
8. Expect disconnections and other errors.
9. New: See the Activity_Resume code in the example. It is needed to handle reconnections.

See the attached example.

Tips & Notes

- Make sure that you are able to connect to the drone with the DJI app. Not all Android devices have proper support for USB connected devices.
- You will see a dialog that asks you whether you always want to start the DJI app when the USB is connected. Click on "This time only". Otherwise you will need to uninstall the DJI app as it will get an exclusive permission to use the USB device.
- Use B4A-Bridge to connect the IDE to the Android device.
- Supported drones: https://developer.dji.com/mobile-sd.../product_introduction.html#supported-products
- Use the simulator to test your app. It works well.
https://developer.dji.com/mobile-sd...on-development-workflow/workflow-testing.html

- Don't fly the drone indoors.
- Check the GPS status. All the nice automatic features will fail without the GPS. Should be 4 or 5.
- Make sure that the home location is set before flight.
- Always be prepared to manually control the drone.

Download the native libraries and copy them to the additional libraries folder:
www.b4x.com/android/files/dji_additional.zip
Note that only 64 bit binary is included inside dji-sdk-4.15.aar. You can download the full aar with both 32 bit and 64 bit binaries here:

https://repo1.maven.org/maven2/com/dji/dji-sdk/4.15/dji-sdk-4.15.aar

During development it will be faster to use the smaller aar file.

Download the attached library and copy it as well.

Updates

- 4.70: Based on SDK 4.15. Check the updated example and don't miss the Activity_Resume code.
- 4.60: It is based on DJI SDK v4.14-trial1.
It requires B4A v10.2+
The minimum Android version is 5.0.

Start with the attached example. Note that the hotspot mission calls ExitApplication. You must configure a reasonable coordinate before you test it (and remove the ExitApplication).

 

[susu]

It's amazing! Thanks Erel.

 

[freedom2000]

Really Great !

 

[wonder]

@Erel, it's probably worth mentioning that using a (dual-analog) physical gamepad would fit like a glove in this kind of projects.

https://www.b4x.com/android/forum/threads/generic-gamepad-support-source-code.53518/

 

[Erel]

Another example is attached. This one adds a MJPEG server to the app. It allows other clients to connect and see the camera feed.
The url is displayed in the app screen.


The compiled APK is available here: www.b4x.com/android/files/DroneMJPEG.apk
Consider it a beta app and always be prepared to manually control the drone.

 

[Widget]

That's a very impressive video. If I had one of these drones. I'd never get any programming done.

Is there any way in Android to improve the readability of the text that is superimposed on top of the background video? In the first demo you have black text on top of the video which looks OK if the background is bright. But if the background is dark the black text is hard to read. When operating a drone you really need to be able to read the text clearly.

The first solution is to put a white border around the black text, or a back border around white text. This will help the text to stand out on any type of background it is superimposed on. See http://stackoverflow.com/questions/8960105/how-to-add-border-to-a-text-in-textview-android
Is this possible in B4A?

If that isn't possible, then a quick "solution" would be to create a new Label class (or add the properties to the existing Label) that has a 2 new properties:
ShadowColor and ShadowOffset. The result would be more readable text on an image or video. See sample image.

 

[Erel]

The shadow can be added with this code:

Sub SetTextShadow(lbl As Label)
   Dim jo As JavaObject = lbl
   Dim radius = 2dip, dx = 0dip, dy = 0dip As Float
   jo.RunMethod("setShadowLayer", Array(radius, dx, dy, Colors.Yellow))
End Sub

 

[Widget]

This is an improvement. (See image)

But there are 2 problems.

1. Doesn't "setShadowLayer" require hardware acceleration to be turned on? And it is turned on for targetSDK >= 14 but not for Android 6?
2. The shadow it produces uses a blur, which is fine on large text but is barely noticeable on smaller text. Is there a way to eliminate the blur so it works better on smaller text?

TIA

Sub Activity_Create(FirstTime As Boolean)
    'Do not forget to load the layout file created with the visual designer. For example:
    'Activity.LoadLayout("Layout1")
    Activity.Color = Colors.Black
  Label1.Initialize("")
    Label1.Text      = "Testing"
    Label1.TextSize  = 100
    Label1.TextColor = Colors.Blue
    Activity.AddView(Label1, 20Dip, 20Dip, 500dip, 500dip)
   
    Private jo As JavaObject = Label1
'    Private Radius = 4dip, dx=0dip, dy=0dip As Float
    Private Radius = 10dip, dx=0dip, dy=0dip As Float
    jo.RunMethod("setShadowLayer", Array(Radius, dx,dy, Colors.Yellow))
End Sub

 

[omarruben]

** my mistake *** i had a old b4a version
i did get the keys from DJI and google maps...
al works fine now AWESOME

Hi, i have downloaded the demo files , i ahve error on 1.bal not found and unknow typoe googlge map, can you please check i am so exited about this library, thank you

 

[Erel]

But there are 2 problems.

1. Doesn't "setShadowLayer" require hardware acceleration to be turned on? And it is turned on for targetSDK >= 14 but not for Android 6?
2. The shadow it produces uses a blur, which is fine on large text but is barely noticeable on smaller text. Is there a way to eliminate the blur so it works better on smaller text?

Please start a new thread for this.

i did get the keys from DJI and google maps...
al works fine now AWESOME

Which drone are you using?

 

[gvoulg]

Great Library Erel.
I have a Phantom 3 advanced and I will try to test it.
What about waypointmission? Are you planning to wrap the rest of the functions in DJI's SDK?
George

 

[Erel]

I was waiting for demand

It should be very simple to add support for other types of missions. I can also show you how it can be done with JavaObject.

Start with this example and once you get it working (the USB exclusive permission can be a bit annoying) we can extend it.

 

[DonManfred]

If there is anyone who want to spend a Phantom 3 to me i would be glad to extend the lib

PD: okok, i need to win the lottery i guess ;-)

 

[gvoulg]

first impressions... Fantastic!!!!!!
I manage to get it to work on the dji emulator. (drone connected to the pc)
Bad weather so its difficult to test on field but all process is very promising.
Most difficult thing was to install DJI's USB driver to set the emulator to work (has to do with signature of driver)
Thank you Erel!!
Waiting for more
George

 

[TomDuncan]

I have a phantom 3 standard which does not use the USB connection from the transmitter to the tablet.
Will this still work? I will test today and check.
What a great addition this will make, my love of filming, drones and b4x, yummy.

 

[Erel]

I have a phantom 3 standard which does not use the USB connection from the transmitter to the tablet.
Will this still work? I will test today and check.

I think that it will work.

 

[TomDuncan]

Just did a test using your compiled apk.
It just sits with a blank screen on left and right (google)
What might be happening is the lack of usb connection with the Phantom 3 standard
All I do is connect the Android device using the dji wifi PHANTOM3_2fd145

Any thoughts.

Also while I was generating my own using B4A it would go through and look as though it sent the apk via Bridge but nothing would happen.
Maybe this has something to do with file size or Tom finger errors.

Tom

 

[Erel]

Also while I was generating my own using B4A it would go through and look as though it sent the apk via Bridge but nothing would happen.

It can take a minute for the app to be installed due to the library size.

Connect the Android device with a USB cable to the PC and enable USB debug mode. It will allow you to see the logs.

 

[PABLO2013]

regards I have a standard phantom 3, but the connection is via wifi (produced by the control).
I think the phantom advanced and pro if they are connected by usb cable as these controls if you have the port, in my case as you could do ....
on the other hand I did some tests, for now ask me to be the first time is due Register the application ... but being using the wifi with the control can not ... some help .... previous examples about which phantom version were made, thanks

 

[Erel]

What happens when you run the example from the first post?