I am looking for **the simplest way** to produce reference voltage **ON=1.0V** and **OFF=0.0V** from the Raspberry Pi. I have learned that GPIO outputs are not very precise, and according to [Exploring the 3.3V Power Rail](https://raspberrypise.tumblr.com/post/144555785379/exploring-the-33v-power-rail), 5V power rail is also not very stable. However the document suggests that 3.3V power rail is fairly stable, so I constructed this simple circuit:

[![enter image description here](https://i.stack.imgur.com/rY7WX.png)](https://i.stack.imgur.com/rY7WX.png)

Of course I would put voltage divider at the end to get the required 1V.

The required conditions are

* at most 1% voltage drift,
* output current can be small (to be supplied to another operator amplifier).

Does this circuit make sense? Is 3.3V power rail stable enough for this purpose? Can you propose another, not too complicated circuit, which would be even better?