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SHT11 Sensor: Incorrect Readings, Calibration?
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

SHT11 Sensor: Incorrect Readings, Calibration?

by fmc on Wed Feb 06, 2013 3:48 am

Hi - I am using the SHT11 Temp/Humidity sensor with an Arduino Uno. I followed multiple people's kind insturction guides on how to get things going but am getting wacky readings along the lines of -40 C, -40F and -5% humidity...Any ideas?

I connected this way and used the below .pde sketch (ReadSHT1xValues.pde)

Pin 1 SHT11 ---> pin 10 on Arduino / "dataPin"
Pin 3 SHT11 --->Pin 11 on Arduino / "clockPin"
Pin 4 SHT11 --> Ground on Arduino
Pin 8 SHT11 ---> 5v Arduino (also tried 3.3V)

I know I can offset this error in my code but....this beats the point of paying for the sensor so any ideas would be so appreciated!

Thanks so much,

FM


Code: Select all | TOGGLE FULL SIZE

/**
* ReadSHT1xValues
*
* Read temperature and humidity values from an SHT1x-series (SHT10,
* SHT11, SHT15) sensor.
*
* Copyright 2009 Jonathan Oxer <jon@oxer.com.au>
* www.practicalarduino.com
*/

#include <SHT1x.h>

// Specify data and clock connections and instantiate SHT1x object
#define dataPin  10
#define clockPin 11
SHT1x sht1x(dataPin, clockPin);

void setup()
{
   Serial.begin(38400); // Open serial connection to report values to host
   Serial.println("Starting up");
}

void loop()
{
  float temp_c;
  float temp_f;
  float humidity;

  // Read values from the sensor
  temp_c = sht1x.readTemperatureC();
  temp_f = sht1x.readTemperatureF();
  humidity = sht1x.readHumidity();

  // Print the values to the serial port
  Serial.print("Temperature: ");
  Serial.print(temp_c, DEC);
  Serial.print("C / ");
  Serial.print(temp_f, DEC);
  Serial.print("F. Humidity: ");
  Serial.print(humidity);
  Serial.println("%");

  delay(2000);
}


fmc
 
Posts: 2
Joined: Wed Feb 06, 2013 3:29 am

Re: SHT11 Sensor: Incorrect Readings, Calibration?

by adafruit_support_bill on Wed Feb 06, 2013 7:28 am

Can you post a photo showing all your connections? Those readings are way too far off.

adafruit_support_bill
 
Posts: 45727
Joined: Sat Feb 07, 2009 10:11 am

Re: SHT11 Sensor: Incorrect Readings, Calibration?

by fmc on Wed Feb 06, 2013 12:35 pm

thank you so much for any help: seriously.
i followed another woman's photo/code. worked for her but not me. here is what i did:
Attachments
ardSHsm.jpg
ardSHsm.jpg (954.4 KiB) Viewed 770 times
fmc
 
Posts: 2
Joined: Wed Feb 06, 2013 3:29 am

Re: SHT11 Sensor: Incorrect Readings, Calibration?

by adafruit_support_bill on Wed Feb 06, 2013 1:41 pm

You might try a 4.7K resistor on the clock as in the data sheet: http://www.parallax.com/Portals/0/Downl ... onDocs.pdf

adafruit_support_bill
 
Posts: 45727
Joined: Sat Feb 07, 2009 10:11 am

Re: SHT11 Sensor: Incorrect Readings, Calibration?

by mynegation on Sat Feb 09, 2013 1:14 am

I had similar readings when I attached CLOCK and DATA to the wrong pins on Arduino (basically 9 and 10 instead of 10 and 11 that were specified in the code). Once I rewired to correct pins, everything started working as expected. Your wiring seems to be consistent with the code, but I would check the quality of wiring first.
mynegation
 
Posts: 1
Joined: Fri Jan 18, 2013 1:58 am

Please be positive and constructive with your questions and comments.