Categories
Android

Setting Android Settings

On the Android platform all the system wide settings that are accessible via the Settings app are also accessible to your app. You just need to add the uses permission WRITE_SETTINGS. Here is a simple Delphi XE5 example for changing the screen timeout.

First you need the following in your uses clause:

Androidapi.JNI.Provider, // JSettings_SystemClass
FMX.Helpers.Android; // SharedActivityContext

Here is the code to read and set the Screen Off Timeout:

function GetScreenOffTimeout: Integer;
begin
  Result := TJSettings_System.JavaClass.getInt(
    SharedActivityContext.getContentResolver,
    TJSettings_System.JavaClass.SCREEN_OFF_TIMEOUT,
    15000);  // 15 seconds is default is not found
end;

function SetScreenOffTimeout(ATimeOut: Integer): Boolean;
begin
  Result := TJSettings_System.JavaClass.putInt(
    SharedActivityContext.getContentResolver,
    TJSettings_System.JavaClass.SCREEN_OFF_TIMEOUT,
    ATimeOut);
end;

In the GetScreenOffTimeout we pass a default value to use if none is found. I passed in 15000, which is 15 seconds, or the smallest value for my phone. The largest value on my phone is 600000, which is 10 minutes. It appears you can set it to any value, even one that the settings app doesn’t explicitly list as an option.

There are lots of other settings available for your adjustment.

Categories
webinar

Oh Yeah, the Ouya!

The Ouya is an Android powered game console / set-top box that you can pick up for $99. Not only is it a cheap game console, but it is also an affordable Android platform designed to drive big screen TVs. Easily turn a TV into a wall mounted dashboard or living picture frame.

Once the ADB driver is installed, You can develop for and deploy to it with Delphi XE5 just like any other Android device.

This video is from our Making the Connection: Programming Devices and Gadgets with RAD Studio webinar. Check out the on-demand replay and download the full source code too.

The Ouya has an SDK that goes beyond what I showed above. I’ll be revisiting it with more updates in the future.

Categories
Android Brain Computer Interface devices gadgets iOS Mobile

Connecting to the Parrot AR.Drone 2.0 from Delphi XE5

My first thought when I see cool technology is to figure out how to connect to it with Delphi. So the day I got the Parrot AR.Drone 2.0 quadricopter I started working on Delphi interface. By the time evening rolled around the batteries were dead (after a couple recharges), but I had a basic interface working. The official developer guide seemed to be a little out of date, or I was reading it wrong, but once I got my facts staight, connecting was really easy. http://www.youtube.com/watch?v=aaGe2aERwgI The Parrot AR.Drone has it’s own access point. Once you’ve connected to it, then it is simply a matter of sending UDP packets for the basic controls. To accomplish that I simply used the Indy UDP Client: TIdUDPClient. Each command is sent with an increasing sequence number, so I initialize my interface as follows:

  udp := TIdUDPClient.Create(nil);
  udp.Host := '192.168.1.1';
  udp.Port := 5556;
  seq := 1;

The AR.Drone is always at 192.168.1.1 since it is the access point, and the port for communication is 5556 (one of a few ports, but the one we need for now.) It is worth pointing out that if you’ve previously flown your AR.Drone with the FreeFlight mobile app then you may need to reset your drone to unpair it. Otherwise it is paired to only that device. The commands are formatted with an AT* prefix, and a series of arguments. For example, to take off, the command is AT*REF=1,290718208 where AT*REF is the command, 1 is the sequence number (always the first argument) and 290718208 is a bitmask that means take off. I created a SendCommand routine that looks like:

procedure TARDrone.SendCommand(cmd, arg: string);
var
  full: string;
begin
  if not udp.Active then Connect;

  full := Format('%s=%d,%s' + Chr(13), [Cmd, Seq, arg]);
  Seq := Seq + 1;
  udp.Send(full);
end;

Notice the command is terminated with a carriage return (#13). The documentation says line-feed (#10), it is wrong. Supposedly you can send multiple commands in the same message, if they are separated by the carriage return. I haven’t tested that. Then I can send the some common commands like this:

  SendCommand('AT*REF','290718208'); // Takeoff
  SendCommand('AT*REF','290717696'); // Land
  SendCommand('AT*CONFIG', '"control:altitude_max","10000"'); // unlimited altitude
  SendCommand('AT*CONFIG', '"control:altitude_max","5000"'); // restrituded altitude - unsure what units 500-5000.
  SendCommand('AT*PCMD','1,0,0,0,0'); // Hover (stop movement)

PCMD is the move command. It takes 5 arguments (after the sequence number.) The first is the controller type, which we are leaving 1 for now. The next 4 are phi, theta, gaz, yaw and they are floating point numbers in an integer representation. This is where it gets interesting. The documentation says:

The number –0.8 is stored in memory as a 32-bit word whose value is BF4CCCCD(base 16), according to the IEEE-754 format. This 32-bit word can be considered as holding the 32-bit integer value –1085485875(base 10).

The first way I thought of to access the same memory as two different types is a variant record. So I came up with the following helper routine:

function IEEEFloat(const aFloat: Single): Integer;
type
  TIEEEFloat = record
    case Boolean of
      True: (Float: Single);
      False: (Int: Integer);
  end;
var
  Convert: TIEEEFloat;
begin
  Convert.Float := aFloat;
  Result := Convert.Int;
end;

Using that I built a move routine that takes 4 singles (32-bit floats) and sends them as integers:

procedure TARDrone.Move(const phi, theta, gaz, yaw: Single);
begin
  SendCommand('AT*PCMD',Format('1,%d,%d,%d,%d',
    [IEEEFloat(phi), IEEEFloat(theta), IEEEFloat(gaz), IEEEFloat(yaw)]));
end;

Now if I want the drone to go up I can call:

  Move(0,0,5.6,0); // positive gaz is upward acceleration

Now it is just a matter of figuring out how to the rest of the movements map to the physical worked and building a user interface on Android, iOS, Windows or Mac. Maybe all 4! Once I build up the API a little bit more I’ll share some full working apps and libraries. Let me know if you are interested in collaborating on such.