#264 DigitalPots/MCP42010

Control the MCP42010 dual 10kΩ digital potentiometer with an Arduino and hardware SPI.

Notes

I’m trying out some digital potentiometers for an application. This is a test of the MCP42010 - the dual 10kΩ version of the MCP41XXX/MCP42XXX.

This is a pretty nice chip:

• independant control of the two wipers via standard SPI
• can be daisy-chained
• 8-bit resolution for the wiper setting
• polarity of the A/B pot connections does not matter
• reset pin (sets wiper to middle position)
• hardware/software shutdown control

Typical Applications:

• Programmable gain circuits
• Programmable differential input amplifier

SPI

It is possible to operate the device in SPI_MODE0 and SPI_MODE3

• SPI_MODE0: Clock Polarity=0, Clock Phase=0
• SPI_MODE3: Clock Polarity=1, Clock Phase=1

It supports a basic command + data byte structure, per the timing diagram from the datasheet:

Unfortunately it appears the MCP42010 cannot handle two commands in a single SPI transaction, hence if A and B wiper settings are different they need to be sent separately. If A and B wiper settings are the same, they can be sent in one command.

Test Program

The MCP42010.ino sketch is a simple test that drives the two wiper outputs with complementary triangle waves. This is what it looks like on a scope:

Construction

I have the MCP42010 in a 14-Lead SOIC package, so I loaded it on an adapter for breadboard tests..

Credits and References

• MCP42010 datasheet - parts.io
• Arduino SPI library
• SPI - wikipedia
• ..as mentioned on my blog