I think the old DAC was working

A project log for /dev/analog0

Primitive analog output device for a Raspberry Pi.

Steven ClarkSteven Clark 05/10/2016 at 17:240 Comments

So, I'm pretty sure it was just my non-functional test file and my DAC was working. The flaw was in my test setup. See I set up a bank of dip switches on a breadboard and ran from power to the input pins. If you're cleverer than me you may have figured it out. I needed the 0s of my resistor network to be at 0v and instead they were floating. No wonder the DAC failed that test. So if you want to build one of these a resistor ladder is probably fine, and you might even avoid having to add a voltage divider to your overly strong output like I did with my AD5330 breakout.