Using Analog Pin as Digital Output while still get Analog input on other pins

Projects General Guidance
1

I need one more digital output pin than is available on the Uno, so I'm looking at using one of the analog pins in digital mode. This is simple enough, but I read the caution below:

The Atmega datasheet also cautions against switching analog pins in close temporal proximity to making A/D readings (analogRead) on other analog pins. This can cause electrical noise and introduce jitter in the analog system. It may be desirable, after manipulating analog pins (in digital mode), to add a short delay before using analogRead() to read other analog pins.

I still need to get analog input readings on two other pins, so my question is, what constitutes "close temporal proximity" and how much of a delay after switching the Analog pin on or off do I need to leave? I'd like to minimize the delay, but still need to get reliable readings on the input pins.

Thanks.

2

Unfortunately, it probably varies from design to design. I would think if you left one unused pin between the different signals, you'd be relatively safe. As for a delay, it probably depends on the duration of the noisy period. I would think a few milliseconds would suffice, but I've no idea what your design entails.

3

I think you'll likely find that taking two analog readings and then using the 2nd reading will be fine.

4

That makes a lot of sense. Thanks.