Arduino NANO controlling two digital potentiometers independently

You need to post the schematic of the buck/boost circuit.

Can't advise you without because it matters exactly how the pots are used.

One Arduino can easily control two pot chips but only if certain conditions re. common earth or reference voltage are met (and there are ways round these problems too .....)

MK

Dear MK

Thank you for taking the time to guide me.

Unfortunately the buck/boost is a proprietary device - no cct is available.

GREAT - confirming once micro controller can do the job.

The buck/boost cct is inexpensive so I can play around.  My Arduino UNO and NANO kit will be arriving soon.

Whilst waiting. I'll order the two dig pots and start with some basic Arduino projects.

During my tertiary education, "modern" programming was in its infancy.....Olivetti Basic, Fortran and did a bit of assembler for Z80 chip.

Did not love it and continued with analogue electr eng.

How the wheel has turned..... Now, at the ripe age of 57.... I have to get to understand Arduion code.....lol

Thanks

Alan

You're thinking of using an MCP41010 - beware - this part needs a 5V power supply and to share ground reference with the Arduino.

None of its other pins must be connected to a voltage exceeding supply + 1V or it will  be damaged.

None of the other pins must be connected to a voltage above 5V or iot won't work correctly.

If, as I suspect, your buck boost is a bit like this one in this article:

https://wiki.beyondlogic.org/index.php?title=WD2002SJ_LTC3780_Synchronous_Buck_Boost_Converter_Ebay_Automatic_lifting_pr…

where the voltage and current control features are described, then the voltage control pot is connected to Vout and you could not use an MCP41010.

(the actual value of the pot is not very important, since the other resistors can be scaled to suit.)

You can't just drop a digital pot in place of a real pot in any circuit and expect it to work.

Unless you have the schematic you are setting yourself up to fail (in a smokey way !).

If all else fail then trace the circuit board out yourself and draw the schematic - it will ensure that you really know what you are working with.

Or post some pictures and someone on E14 may be able to identify it.

MK

Hi Michael

Ooohh.... thanks for the heads up with the 5V issue.

"My" buck/boost is very similar to the one in the URL you gave.  Here is the exact one I want to modify:  https://www.droking.com/dc-buck/60w-power-supply-module-dc-5-30v-to-0.5-30v-automatically-boost-buck-voltage-regulator-d…

I would prefer not to have a smokey experience...... but curiosity killed the cat.
The cct is a double sided pcb and without soldering all components, I will most certainly not be able to translate the cct diagram.

I understand your comment about simply not just plugging in a dig pot.............. but it would have solve dmy problem perfectly

Necessity is the mother of invention......

Thank you very much.  Do have a look at the buck/boost

Alan

That module looks sufficiently different to be uncertain of which regulator chip it uses and how the pots may be connected.

You could try measuring the voltages at the ends of each pot (not the wiper) with respect to zero (gnd) over the range of operation.

If within the range 0-5V - OK, if not then you just can't avoid some trickery and you will get on much better if you know a bit more about the circuit.

I expect that you realise that this module (sub $5 ) will be pretty awful in terms of quality of parts - expect it to be disgustingly noisy (electrically).

MK

Hi Michael

I'll measure the voltage across the pot end points and give feedback later.  Keep you posted.

Yip, appreciate that $5 does not buy a Keithley....

Reasonable start point for a hobbyist i think.

Thx

Alan

Michael,

Datasheet states “Single supply operation (2.7V-5.5V)” and I have used it at 3.3 V but I readily defer to your knowledge if I missed something

Disregard me.  You are referring to over voltage.

Frank

Hello Frank,

The Arduino can work the pot OK, but the pot might not work in the PSU circuit.

The problems start when you use a 5V supply and connect one of the pot ends to a higher voltage (just like you normally would if connecting it to make an adjustable voltage feedback set up).

Any of the pins more than 1V above the supply pin and expect the chip to fail. Any of the pins more than a small amount (perhaps 100mV) above the supply pin and the pot won't work properly.

There are always work arounds but they get very tricky if both ends of the pot "track" are at high voltages.

When we know the voltages on the mechanical pots we can work out how to make it work.

MK

Hello Frank,

The Arduino can work the pot OK, but the pot might not work in the PSU circuit.

The problems start when you use a 5V supply and connect one of the pot ends to a higher voltage (just like you normally would if connecting it to make an adjustable voltage feedback set up).

Any of the pins more than 1V above the supply pin and expect the chip to fail. Any of the pins more than a small amount (perhaps 100mV) above the supply pin and the pot won't work properly.

There are always work arounds but they get very tricky if both ends of the pot "track" are at high voltages.

When we know the voltages on the mechanical pots we can work out how to make it work.

MK

Thanks for additional information and being gentle :-).  I failed to read carefully the first pass through.