Arduino Uno & AD5254 digital pots to simulate automotive sender / sensors


My first Arduino project and I’m working with an engineer online. I’ve been studying various analog gauge Arduino projects all day but I’m still a bit unclear. My goal was to replace the sensors / senders which are used for analog gauges with a digital potentiometer. The problem I’m having, is that the digital potentiometer will only go down to 70 ohms at it’s lowest setting. The sensors I need to replicate have a range of 10 - 300 ohms. The analog gauges get 12V, ground, and the wire containing the resistance simulating the sensor. I’m really close to getting this working as I’d like except for the issue of the bottom range. I read there were many people who used a PWM output to drive the gauge some how. Is there any way to utilize the digipots I have?

AD5253_5254.pdf (526 KB)

These devices look like they have 4 output channels. If you wire them up in parallel, you can get 4 70 ohms resistors in parallel which is 17.5 ohms. Is that low enough? And if these are the 1k versions, the max would be 250 ohms.

If they are the 10k version, the max would be 2500 ohms.

Crafty thinking - I would be using many more outputs than anticipated, but it could be an option. Thanks for the suggestion

Most digital pots, including the AD5254, will let their magic smoke escape as they are only capable of 5 volts maximum on any pin. In addition, they are not rated for the typical current.

What is your sensors resistance range?

You might have to go the Heath Robinson, Rube Goldberg, method of construction.
A servo turning a potentiometer.

As most servos are 0 to 180Deg, most pots are 0 to 270Deg, you may need to get a larger value pot than needed.
For example 10R to 300R, you may need a 500R or 1000R pot and set the servo to sweep just the required range.
This would work if the sensors you are replacing are used a Variable Resistors, rather than Potentiometers.

If you are using a digital pot you have to also consider the current that will be flowing through it at such a low value.

Tom.... :slight_smile: