Novice Needs Assistance emulating POT with Arduino

Using Arduino Project Guidance
#1

I've searched the internet and forums here for some help, and while I found some useful information, I still need some assistance.

I have an XBOX 360 Wireless Racing Wheel. I am trying to control the accelerator and brake pedals using an arduino.

The pedal assembly connects to the steering wheel using a 4 wire RJ-11 connector. Inside the pedal assembly there are 2 small pots, one for the brake pedal and one for the accelerator pedal. I believe the wires are power, ground, pot1 and pot2.

I know you will need some further information but I was wondering the best way to go about something like this. I was messing with PWM to a low pass filter using some resisters and caps but was unsure how to pass this voltage to the steering wheel since the arduino and the steering wheel are separate circuits.

Any help would be appreciated.

#2

Look at this:-

#3

Thanks for the reply Mike, I've looked into those, it was one of the first things I found but I got lost when it came to choosing one.

http://www.digikey.com/product-search/en/integrated-circuits-ics/data-acquisition-digital-potentiometers/2556350?k=ad5204.

Any Suggestions?

#4

You need to measure the resistance of the pots you are trying to replace. Remove the wires and measure with a resistance meter the value between the two outer pins.
It is that value you need.

#5

Just measured one of the pots. It appears to range from about 480 thru 10k. I don't think I need the 6 pot version, 4 should do just fine. I see a bunch of 10k versions, but I still don't have enough knowledge to pick the right one.

Thanks,
Mike

#6

I ordered http://www.digikey.com/product-detail/en/MCP4251-103E%2FP/MCP4251-103E%2FP-ND/1635683

I tried to order the AD5204BN10 but it's no longer an option. Will I have issues using this chip with Arduino. It says it uses SPI.

Thanks,
Mike

#7

Rather than emulating the POT, a more practical approach is to generate the control signal directly.

For this you will need a digital-to-analog (DAC) converter. In its simplest form a DAC can be built with a series resistor and a capacitor (RC element). The output from the DAC will then take the place of the mechanical wiper (the POT center pin). To set desired voltage output, you can use a digital Arduino pin to either charge (output high) or discharge (output low) the capacitor based on feedback to an analog input (ADC). Analog feedback allows you set and track the desired voltage output with high precision and works well with a simple RC element.

#8

That's what I initially started doing before I was turned on to the digital pots. is a DAC similar to a low pass filter?

It's still a little over my head.

#9

Yes, the RC element used as a DAC in this setup can also be used as a low-pass filter. It's a bit tricky to get this to work with PWM, but quite easy with the on/off (charge/discharge) approach and using ADC feedback.

#10

If there is no booster/buffer in the pedals, then you can't generate the sensor signal; you need to generate a resistance for it to work right.

Here's a I2C digital potentiometer with 10 kOhm range: http://www.digikey.com/product-detail/en/MCP4261-103E%2FP/MCP4261-103E%2FP-ND/1635797
It actually has two pots, so you can do both gas and brake with the same device.
And it will work with both 3.3V and 5V Arduinos.

#11

Will I have issues using this chip with Arduino. It says it uses SPI.

No issues SPI will be fine.
Look for the SPI tutorials in the learning section.

#12