analogRead(A0)

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Re: analogRead(A0)

By trackerj
- Sun Jan 31, 2016 7:25 am #40062 Might be a good idea to read thos post about ESP8266 Internal ADC and Voltage divider usage

Also this one about ACS712 shows you ways to properly scale your sensor Output Voltage to meet your ADC input requirements
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Re: analogRead(A0)

By pomelo
- Sun Jan 31, 2016 7:47 am #40065
WereCatf wrote:
pomelo wrote:They claim it outputs 0v to 5v,
ESP8266 has AD0 for 1v.
What value should i expect on AD0 if SHARP MAXES OUT(5v)?


Anything above 1.0V would obviously result in a reading of 1024, you need a voltage divider to bring the sensor's voltage-output into 0V-1.0V - range.




Why do i have values at 0 - 115 in analogread(A0) even when the Dust sensor is MAXed ?
i was never able to see 1024 in analogRead(A0) even when i maxed out the sensor by puffing a cigarette smoke into it..
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Re: analogRead(A0)

By WereCatf
- Sun Jan 31, 2016 8:14 am #40066
pomelo wrote:Why do i have values at 0 - 115 in analogread(A0) even when the Dust sensor is MAXed ?
i was never able to see 1024 in analogRead(A0) even when i maxed out the sensor by puffing a cigarette smoke into it..


No idea, I don't have such sensors.
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Re: analogRead(A0)

By trackerj
- Sun Jan 31, 2016 8:27 am #40067
pomelo wrote:
WereCatf wrote:
pomelo wrote:They claim it outputs 0v to 5v,
ESP8266 has AD0 for 1v.
What value should i expect on AD0 if SHARP MAXES OUT(5v)?


Anything above 1.0V would obviously result in a reading of 1024, you need a voltage divider to bring the sensor's voltage-output into 0V-1.0V - range.




Why do i have values at 0 - 115 in analogread(A0) even when the Dust sensor is MAXed ?
i was never able to see 1024 in analogRead(A0) even when i maxed out the sensor by puffing a cigarette smoke into it..



Are you sure is properly wired and you have the proper power supply for it? Check connections first.


LATER UPDATE:

Found my notes abut this sensor:

- worked OK only with 5V, didn't try that time to use it with 3.3V because the designed system was 5V one.
- min Vout is about 0.7V
- max Vout about 3.7V -> max dust level =0.53mg/m3
- be sure you properly identified the pinout, in my case, don't know how it's yours,with socket on the left side (1 - > 6)
- be sure that you used the 150 ohm resistor for Vled (from what you say looks more like the LED is dead already)
- you need also a 220uF cap as in datasheet
- be sure that your Pulse-driven wave form is giving you tha right ratio for sampling/sleep time

As you said you have many, don't think all can be defective. Used more than 500 of them, never found one DOA.

I hope it helps. Good luck!
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