DroidOnCar :: About the project

About the project

Our system consists of two parts – CAN-adapter and Android™ application.

Video review of our service (in Russian)

Attention!
Stock display must be left connected to the CAN bus, otherwise many stock car functions will not work, because the display acts as bridge between different CAN-buses. It can be hidden under the panel, for example.

Connection instructions

About the adapter

It is a universal CAN-adapter, which is connected to the car OBD-II diagnostic socket, and the tablet is connected to it via USB. The adapter is built on modern and reliable components, and has the following features:

Built-in Power adapter, which can be switched on/off by different events;
Built-in USB-HUB for connecting accessories to the tablet;
4 negative (commute GND) low current outputs for connecting additional devices to the adapter. Outputs working logic is described below;
UART port for external devices such as Arduino or Raspberry;
In future extension boards will be released, such as external sound card, Bluetooth module, input/output module.

Outputs working logic:

Output #1 - switches on when ignition key is turned to ACC, switches off after removing the key;
Output #2 - active when ignition key is in the IGN position;
Output #3 - useful for rear view camera connection. Switches on in 1 second after switching reverse gear on, switches off in 20 seconds after switching reverse gear off, or after reaching 15 km/h while moving forward, what happens earlier;
Output #4 - active when any door or trunk is open.

Attention!
Outputs are low current and withstand maximum current of 500 mA, hence additional devices can be connected to them only via a relay.

Technical characteristics:

Size (LxWxH):
126x71x35 mm
Connection cables length:
1.5 meters
Power voltage (adapter takes power from OBD-II socket):
6-20 volts
Maximum current consumed by the Adapter in working mode:
5 amperes
Accessory USB ports supplied voltage:
5 volts
Accessory USB ports maximum supplied current:
3 amperes, common for 3 ports
Built-in power adapter supplied voltage:
5 volts
Built-in power adapter maximum supplied current:
3 amperes
Additional outputs maximum supplied current:
500 milliamperes

Electrical schema: download here.

About the Android application

This is an Android service, that reads data from the Adapter connected to it via USB, processes it, and displays on the tablet.
Application main screen can be easily configured with only a few gestures – you can choose which BC indicators will be shown there, how much of them, which info will be displayed in the bottom block. Additionally the screen has 6 icons for launching your favourite apps.
We try to make screen appearance as close to the stock display as possible.

The service also implements BC feature – 4 independant copies: "Trip BC", that is automatically reset at the beginning of each trip (time after the service treats the trip as a new one and resets the BC is configured in Settings), and three User BCs, which are reset manually, independantly.
All stock BC indicators are currenly implemented + some additional:

Trip time (stops with engine off are excluded);
Current speed;
RPM;
Fuel level;
Car voltage.

The service also does the following:

Displays Climate-Control and Stock Music data as popups over any open application, when they are changed. This can be disabled in the Settings;
When stock lights are on, it automatically sets Android system brightness accordind to the brightness of the stock Instrument panel, and also automatically switches between day and night modes together with stock lights. This can be disabled and configured in the Settings;
Displays Climate-Control menu;
Displays stock and additional service messages;
Launches any chosen application when reverse gear is switched on;
Allows to control multimedia volume and your music player using buttons on the steering wheel. You can find details about this feature here: player control.

One more useful feature:
All events are being sent to the Android system as Broadcast Intents, so any Android-developer may subscribe to them in his/her application, and implement any logic based on them. Events list can be provided by request.