I am busy working on a project where I need to control a device via a computer, the interface is not at all complicated, I need to basically control 2 potentiometers, to tweak the function of the device. Potentiometers are used in many products, for such things as volume or frequency, controls or any other analogue input. A potentiometer or variable resistor, can change its resistance according to the position of the turning knob.
My goal is to figure out the optimal settings for the pot’s, or rather the optimal resistance the circuit requires. This can be a very tedious job, trying to turn a pot until the optimum is reached, the problem is that there are 2 pot’s that influence the output of the circuit and any combination of one with the other can have an influence.
So I opted to do this optimization automatically, by hooking it up to a computer via the serial port, seams straight forward so far, but how do you control an analogue device via a computer, well I used a Pic microcontroller to interface to the PC and then I found the Microchip MCP4— series digital pots, these are very nice, you hook them up to a circuit and then by sending commands via SPI the output resistance on some of the pins change. I opted for the MCP42050 because it has dual outputs, the 2 in 42050, and it fitted my range of 0 to 50K the 50 in 42050.
I am busy doing a PCB layout and a circuit schematic, will post my results soon…
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