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Topic: Steering Wheel control interface for Subaru Forester (Read 422 times) previous topic - next topic


I'm trying to create an steering wheel control interface for my 2012 Subaru forester that would recieve the outputs recieved from the steering wheel controls (SWC) and then send a different resistance value to the OEM radio.The OEM radio is from a different model that expects to see different resistance values then what my SWC outputs. I contacted a couple of manufactuers of steering wheel interfaces and none seemed to support what I wanted to do so this is why I'm trying to build an Arduino SWC interface.

I've made numerous searches online for Arduino sketches and projects for similar steering wheel control interfaces and this has proven very helpful, althogh none seemed to be exactly like what I think I need for my application when it comes to outputting a resistance ladder. 

The sketch I'm using seems to read the reistance from the SWC with no issue, I just need some guidance/expample of what is the best solution for outputting a variable resistance to the radio.  I pursued 3 options

1.)  A reistance ladder that would be controlled using the arduino digital pins set to low depending on the SWC input recieved.
2.)  A digipot that outputs a variable resistance
3.) A resistance ladder that would be controlled using transistors controlled by digital pins set to high to  swich the transistors.

I tried the first option of the digital pins set to low although I found that the once the digital pins were activated to low they would say in low.  I'm using a Nano, i'm not sure if there is any options such as a pull up/ pull down feature to return the pins back to high?

I looked at the digipot option although the only digipot i have access to was a 10k with 129 steps. 
The resistance values I need to output are 0, 330, 1000, 3110, 100k (no button pressed) Ohms.  I don't believe that the 129 step digipot would cover these values so I did not pursue this further.

I'm currently looking at the resistance ladder option controlled by the NPN transistors (NTE123A) although i'm finding that once the transistor has been switched (saturated) they seem to stay in the saturated position and don't  return to the non saturated phase.  I have played around with setting the digital pins to high to activate the transitors then creating a delay then setting the same pin to Low which seems to return to the non saturated phase although i'm not sure if this is the best solution.

Any advice or sketch examples of a similar solution specifically for what option to pursue would be greatly appreciated.

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