Thanks.
Yeah, I saw that soon after I posted my question.
So, for anyone who might stumble across this: The key is a fixed-length (16 byte) field.

I am using NVS for it’s Flash wear-leveling abilities. I am only storing a small number of Uint_32 values. Is there any advantage to using short keys vs long ones? If I call my keys “A”,”B”,”C”, vs. “This is a very long, and probably needlessly verbose key”, is the amount of storage that each key pa...

The LED can be powered from 3.3v, through a dropping resistor (value is not critical, I’d start with 200Ω). The photodetector needs 5v, so its output needs to be connected to a resistor to act as a voltage divider. Since the pullup resistor is 10KΩ, putting a 10KΩ resistor to ground will limit the “...

I’m not familiar at all with ESPHOME, but I looked on the web at the NTC, ADC and Resistance functions, and it’s a bit vague. Obviously, the attenuator in the ADC directly affects the temperature readings, but I don’t see how the NTC function takes the attenuator setting into account. You need to us...

Do you have a capacitor and pullup resistor on the /EN pin?

What kind of readings are you getting?
Use an ice cube and a hair dryer to expose the thermistor to a range of temperatures, and take readings, noting the actual temperature using a known-good thermometer.

That’s not a 150KΩ resistor - it’s 120Ω (or maybe 10KΩ - hard to tell).

ADC’s are very sensitive to grounding issues. Ground bounce caused by high-current digital peripherals will manifest as spurious signals at the ADC. Grounds should be single-point, or ground plane, and not thin, meandering traces. See: http://www.ti.com/lit/an/sbaa052a/sbaa052a.pdf?HQS=sbaa052-aaj&t...

Why do you have the rectifier in series with the capacitor on the output of the regulator?

How are your grounds?