Arduino and Android to control my Hot Rod car electronics

Projects General Guidance
1

Hello All,

I'm new to Arduino but having really good results so far..

I'm using Arduino ADK to interface with my car electronics (ISIS). The Arduino is controlled by an Android Tablet or Smartphone. I'm using the ISIS Power intelligent multiplex system on the back end. http://www.isispower.com/ The ISIS MasterCell or controller is basically a PIC microcontroller. The Arduino digital output pins are connected to the ISIS controller (MasterCell) digital input pins.

It goes something like this..

Android Tablet --> wireless --> AP --> Arduino ADK w/Eth (digital out) --> MasterCell input --> CAN BUS --> PowerCell --> +12v to lights, pumps, fans, etc..

The ISIS controller requires a logic low on the input pins to turn on an output (+12v) of the PowerCell. I configured the Arduino output pins to be HIGH at startup (void setup) for the (Switch OFF) position. When I want to activate the function I digitalWhite(pin, LOW) to provide the LOW that ISIS needs to turn on the output. This is all working fine except for an unexpected feature on the Arduino. If I remove power to the Arduino board, it takes all the output pins low and turns on all the outputs of the ISIS. I guess I expected the Arduino output pins to go to a high impedance state when power was removed but that doesn't appear to be how it works.

The possible solution I'm considering is to add Hex inverters between the Arduino and the ISIS controller and change the Arduino output logic to be LOW for the off function and HIGH for the on function. Is this my best option? If so, any recommendation for the inverter chip? I'm considering the MC74F04N as I have those readily available.

Thanks in advance!!

Dave

2

Alot of views but no response. Did I not provide enough information?

3

I opened your post hoping to see arduino doing something neat in a car, I guess a lot of others did as well.

Why do you want to power down the arduino while the rest of the system is still operational ?

Duane B

rcarduino.blogspot.com

4

I don't want to power down the Arduino, I'm just testing scenarios to see what happens. If I were to blow a fuse for the Arduino or if the board went bad, I don't want it to turn on everything in the car including the engine, starter, fans, etc.. Could be bad..

I'm building a 67 Camaro Pro-Touring car. The car itself is still on the rotisserie. I can show the electronics working as I have it all setup on a work bench. I have the motorized headlight covers, window motors, door lock actuators, and various LED's to simulate other outputs. The Arduino part is going well, I haven't had any trouble getting a engine coolant temp sensor working to control the radiator fan and the sketch to control the inputs/outputs is straight forward. The Android part is working but not stable. I'm using Car Home Ultra for the home screen interface and NetIO to control Arduino inputs. It really looks great..

5

Hi,
How about trying some pull down resistors, these will pull the inputs low when there is no signal from the Arduino - try connecting a 10K resistor to ground on each of the lines between the Arduino and the other device - assuming that you want the other device to read lows on its inputs of the Arduino fails ?

Duane B

6

Dasmith needs a low as logic level to turn things ON.

So in this case you can try to switch on the internal pull up resistors on the digital pins you use.

void setup
{
digitalWrite(2, HIGH);    // enable the 20k internal pullup
...other code
}

If that does not work pull them high with a 10 K resistor.

Paco

7

Sorry, rereading I see that you want the ISIS inputs high - use 10 K pull ups connected to Vcc rather than connecting them as pull downs.

backbone - the OP is concerned what will happen when the Arduino is turned off, I don't think the internal ATMega pulls will have any effect then ?

Duane B

8

Ah, that should work although it will have to be from another 5v supply instead of the Arduino 5v..