Meg2560 Inputs and outputs

Other Hardware Sensors
1

Hey guys I want to build a larger input output module to relay via mqtt to home assistant.

i was looking at doing this with a pi but it turns out the mega has a lot more inputs and outputs. Please be gentle as I am just going down this road but here are my questions:

  1. If I use an ethernet shield do I reduce the number of inputs / outputs?

  2. Can I use analog inputs (eg reed switches) as an input end point?

Thanks in advance!

Neil

2

An Ethernet shield merely deprives you of using the five pins it uses for other purposes. This is not normally a problem with a Mega.

Your other question is unintelligible. I would not expect a reed switch to be an analogue device. Just in case you are not aware of it, the Mega's analogue pins may also be used as digital.

3

A reed switch that is a physical switch isn't considered analog? I would imagine an analog input would measure a momentary button press? Is that correct?

Thanks for the clarification on the ethernet shield. It sounds like it wouldn't reduce the number of inputs at all.

Thanks!

Neil

4

Digital pins read on and off, a switch

Analog pins read variable values, 0 through 1023, from 0 to +5 VDC

Analog pins are also digital pins

5

heffneil:
A reed switch that is a physical switch isn't considered analog? I would imagine an analog input would measure a momentary button press? Is that correct?

Analog inputs are used to measure a variable voltage, like from a potentiometer or many sensors.

Digital inputs are used for things that are either HIGH/LOW or ON/OFF i.e. have only two positions of interest. Reed switches, buttons and most other switches fall into this input type.

Steve

6

Wow I had that completely backward! See I learned something - Thanks!

7

Well, there you go - and you probably ended up with more pins than you thought.

8

Yeah I wasn't thinking "digital is 1 or 0) I was thinking it was more precise with voltage levels and whatnot.

Thats why I was backwards like a float was digit and analog would be on or off. I was thinking about it completely wrong.

I am assuming analog could be set to use a pull up resistor for a digital style input?

Thanks!

Neil

9

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