Almost instant startup of Realdash cluster when starting car

Hello all,

I am at a certain point now to design the hardware for the LCD instrument cluster. This is the part I think I need the most help with from people who already have experience with this.

My idea:
Cluster turns on when unlocking the car/turn on the ignition and should show a custom image with date, time and odometer (side question: can I get the real odometer value from OBD2? If i have a text gauge with odometer, it shows a verry inaccurate value). Anyway, this should be a very fast proces, because it would be very unusefull to wait +20 seconds to get the cluster loaded.
When turning of the car, cluster stays on, until car gets locked or when there is no “inginition” signal for a certain time, say 20 seconds.

My original cluster behaves the same way. When car gets unlocked, the little LCD display on my cluster turnes on. It stays on when I turn on the car (acc or start) or shuts down if I do not turn on the car within 20 seconds or when I lock the car before that 20 seconds.

The main “computer” runs on Android to run Realdash and is connected to the LCD and to the OBD2 port with USB adapter. I think I have to design/use something that puts the Android computer into a sleepmode when turning of the car, so it won’t drain the battery (at least 48h of sleeptime) and wake it up very fast when entering/starting the car. Also it should shutdown completely when it has not wake up after 48h, so it won’t fully drain the battery if I do not use the car for more then 48h.

I hope you can help me on this one.

Thank you very much in advance.

I’m setting up a system with a 12.3 "screen, the android runs on a Khadas Vim 3 board, in standby consumes 15mA at 12V and wakes up from standby in about 3 seconds.

Thanks for the quick reply. This seems very interesting. How did you set it up to go in standby mode when shuting down the car and waking it up when entering/starting the car and what about your 12inch screen, how do you control that power? You say it wakes up in 3 seconds, what about the connected hardware, like the CAN/OBD adapters? You say Realdash is up and running AND receiving data 3 seconds after wake up? That is very nice and interesting.

Hope you can help me on this one, with configurations etc.

Great, I am also need that. I have single board PC (Chinese rooted android board) for 10.25" LCD without shutdown switch!

Can you please share with us how do you manage to make Khadas board get into sleep mode?

Can any one help us with TASKER application?


I found a useful video on youtube.



Macrodroid is a wonderfull tasker :smiley:
i use it to control my tablet in the car

Yes, great thing! Have you learned how to create macros for external control? For example from arduino?


unfortunately not, so far i only have macrodroid on android, but my next project is a raspberry with android, but it should be the same with macrodroid.

i control the following things with macrodroid on my tablet:

  • screen dimming at sunset and brightening at sunrise
  • switch on & off wifi, sound & screen when starting or switching off the engine
  • start tomtom amigo with wlan connection
  • start realdash with bluetooth connection

i like it… :smiley:

turn on and off Wi-Fi, sound and screen when starting or turning off the engine

how is it implemented?

i use the ignition current (charging current) of the tablet by creating a macro that triggers the charging current to be ON or OFF

trigger :

  • charging current on
    actions :
  • unlock screen
  • screen on
  • keep device awake
  • switch on wifi
  • deactivate mute
  • wait 5 seconds
  • start realdash

you can maybe do something with it?

Ralf :smiley:

Clear. Thank you!

I also use the VIM3 with android.

Here is a code for a Arduino Mini or what ever you like. You would need 2 Relays. One that comes from the ignition (this will be the button on the Arduino) and one that controls the VIM3 button. The VIM3 has 2 round pads on the underside near the 3 buttons. You need to solder one wire to each pad. Those wires go to the second relay.

So when you start the car the first relay closes, then the Arduino will close the second open relay that goes to the VIM3 for 0.3 seconds. The VIM3 wakes up! You turn the car off, the first relay opens, and the Arduino will close the second relay again for 0.3 seconds and the VIM3 goes to sleep.
Total cost about $10

#include <Arduino.h>

const byte ignPin = 5; // Connect to IGN over a Relay Ground
const byte vim3Pin = 16; // Connect to VIM3 Sleep/Wake Button Relay
unsigned long startTime;
unsigned long period = 300;
boolean flashing = false;
byte count = 0;
byte previousButtonState;

void setup()
  pinMode(vim3Pin, OUTPUT);
  pinMode(ignPin, INPUT_PULLUP);
  digitalWrite(vim3Pin, HIGH); 

void loop()
  if (!flashing)
    byte currentButtonState = digitalRead(ignPin);
    if (currentButtonState != previousButtonState && currentButtonState == HIGH) 
      flashing = true;
      count = 0;
      startTime = millis();
    previousButtonState = currentButtonState;
    unsigned long currentTime = millis();
    if (currentTime - startTime >= period)
      digitalWrite(vim3Pin, !digitalRead(vim3Pin));
      startTime = currentTime;
      if (count == 2)
        flashing = false;
        digitalWrite(vim3Pin, HIGH); 

The 12.3 "screen is connected directly to the ignition key, to khadas with a constant 12V supply, I use a trigger on Realdash to disconnect the Realdash from the ECU and by Macrodroid close the bluetooth wifi connections and turn off the screen, then Khadas manages to enter sleep mode.

do you or anyone on this board have a schematic on how to build this ? theres not a lot of information on how to build/set this up. this is pretty much exactly what i want to do with my setup.

Hope this helps, never used that program to draw a schematic.

The pin A0 and A1 are just examples.

This helps a ton!! Thank you so much!!

If you want to build a real dashboard, then you don’t have to use the OBD. obd is a diagnostic bus that works on demand. this is a bad way to get data. the correct way is to read the сan-bus.
in addition, if you want to replace the factory dashboard, then you must send the same data to the can-bus that the factory dashboard sends. in some cars this is the hardest part. and some cars without this data will give an error. also in some countries for manipulating the dashboard, namely the odometer, you can get a large fine. therefore, before doing the tidy instead of the factory one, you will have to spend a lot of time studying it.

but in general it looks something like this.

Hi, can I give you an idea that works for me!

Make your Android turn on when you open the car door!

So when you want to start the car, Android would already have some data loaded, I use Arduino to control the screen on and off automatically, also to automatically charge the battery of the Android tablet and send data from lights, gasoline, etc. .
OBD for RPM, speed, temperature, TPS …

Sorry, I use a translator, my language is Spanish.
Realdash is fantastic … :smiley:

By the way, this is exactly how it is implemented in my car! I disarm the car and the Android is loading. After arming, after 2 minutes, power is no longer supplied to Android!


I tried to use MacroDroid for open RealDash, but it says it needs rooted device.
I tried to root Samsung Galaxy Tab A7 Lite , but i failed.
Is there any easier way or other app for running Realdash for example then when there is charge in usb?