I2C port expanders PCF8575C vs. MCP23017

I need a few extra I/O pins so I did some "research" online.

Sparkfun offers PCF8575C breakout board: https://www.sparkfun.com/products/8130

Adafruit sells MCP23008 and 23017 breakout boards: http://www.adafruit.com/products/593 http://www.adafruit.com/products/732

I am comparing their specs (links on their sales pages). It seems MCP230xx has wider operating voltage range and has several interrupt options and higher max I2C bus speed (none really matters to my project). PCF8575C is a 5V chip and has open drain interrupt.

Price-wise it is the opposite. PCF is twice the price of MCP:



I must have omitted something here. So if you have used either or both, which do you recommend me use? I am sensing rotary encoders and buttons. I will end up using 8-bit expander.

OK, after more reading online and on the spec sheet, I found out that PCF is quasi bidirectional and has a very crude I2C protocol, no registers. It does have some high current drive capabilities for LEDs though. Maybe I'll use the MCP.

The 23017 etc are very common and I’m sure there are libraries to drive them, not sure that is the case with the 8575.


Graynomad: The 23017 etc are very common and I'm sure there are libraries to drive them, not sure that is the case with the 8575.


There is a library for the 8575 at Sparkfun. Jim

Yep, Adafruit has libraries to drive the microchip ics and sparkfun has a library for the TI ic. They both seem to be easy to drive but the MCP has more features.