I am using a simple voltage divider that is shown on this tutorial at Adafruit
At the bottom under the Self-Heating heading it states...
To avoid this heating, you can try connecting the 'top' of the resistor divider to a GPIO pin and set that pin HIGH when you want to read (thus creating the divider) and then LOW when you are in low power mode (no current will flow from 0V to ground)
What is actually classed as the top of the divider?
Does it mean instead of running the resistor from 3.3v rail it should come from another pin (digital/analog) which can be set high/low .
The “top” comes from the way it would be drawn in a proper schematic. Ground at the bottom, power from the top, signal flow from left to right in, say, an amplifier circuit &c.
Yes. You'd use an output-pin (an I/O pin configured as output). Most of the time it would be low then you write a high just-before you take a temperature reading, before it has a chance to heat-up.
In the real world I'd be surprised if it makes that much difference.
