ESP8266 Community Forum

- Fri Oct 14, 2016 4:19 am #56501 Hi,
the analog pin would read ~1/3rd (per voltage divider R2/R3, resulting from the fact that range of analog pin is only 0..1V) of the voltage that results from the voltage divider R6/Rx (R7 or R8 or R9) whichever pushed (sideffects from R1, R1+R2 beeing parallel to Rx) and internal resistance of analog pin neglected).

so expect to read something like (3300*Rx/(1+Rx))*100/320 mV

- Fri Oct 14, 2016 11:01 am #56518

Simple circuit attached, allows 3 buttons, value are specific. Hope this helps.
Remember to add 10k resistor from spare GPIO to CH_PD to keep active while functions are performed.

AD Buttons CH_PD.PNG

Regards Dans

So I'm going to ask a stupid question, because I'm finally getting back to looking at this and breadboarding this up... but wouldn't the analog pin read basically "nothing" because there is a 220k resister sitting in front of it?

Hi @shoelessone I think a basic electronics course would serve you well. You will then realize how I designed the circuit I gave you. It is a complete solution to your problem.

Hope this helps

Dans

- Fri Oct 14, 2016 11:36 am #56520

Hi @shoelessone I think a basic electronics course would serve you well. You will then realize how I designed the circuit I gave you. It is a complete solution to your problem.

Hope this helps

Dans

I tend to agree - or at least I need to spend a bit more time stepping through the circuit. I actually breadboarded the entire thing last night, plus some additional components, and the readings I'm getting from the ADC pin are not as I'd have expected (i.e. not working). That was really the impetus for my question here, but at the end of the day you're right, I have a very entry-level understanding of some of these concepts (i.e. a "voltage divider").

Thanks again for your help, I very much appreciate it!

- Fri Oct 14, 2016 11:59 am #56521

Hi @shoelessone I think a basic electronics course would serve you well. You will then realize how I designed the circuit I gave you. It is a complete solution to your problem.

Hope this helps

Dans

I tend to agree - or at least I need to spend a bit more time stepping through the circuit. I actually breadboarded the entire thing last night, plus some additional components, and the readings I'm getting from the ADC pin are not as I'd have expected (i.e. not working). That was really the impetus for my question here, but at the end of the day you're right, I have a very entry-level understanding of some of these concepts (i.e. a "voltage divider").

Thanks again for your help, I very much appreciate it!

Check out this site for learning electronics, I make sure all my students have this link, It is an awesome repository of knowledge.

http://www.electronics-tutorials.ws/

Hope this helps you.

PS: Do not expect large readings on the A>D input, make sure you meter is on VDC low setting if not an auto-range meter.