Pages: 1 [2] 3 4 ... 8   Go Down
Author Topic: Class for DHT11, DHT21 and DHT22 (temperature & humidity)  (Read 57833 times)
0 Members and 1 Guest are viewing this topic.
Global Moderator
Netherlands
Offline Offline
Shannon Member
*****
Karma: 222
Posts: 13867
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


Probably your sample frequency is too high, IIRC the datasheet advices 2000 millis between samples.
Can that be the problem?
Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

0
Offline Offline
Newbie
*
Karma: 0
Posts: 35
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

A quick update:
I started playing around a bit more and fixed the problem.   It seems that i needed to drop the comma after the sensor request (dht.temperature) instead of (dht.temperature, 1).  I'm not sure why that matters.   I'm getting serial prints using the previuos codes.
Logged

0
Offline Offline
Newbie
*
Karma: 0
Posts: 35
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Sorry, missed a comment in between.

I'm pretty sure I'm sampling every thirty seconds.  However, I just realized that my code is getting the data several times in each iteration.  I'd think that this would simply get the old values, but perhaps not.  I've done some code revisions.  I also changed the temperature format to the US standard Fahrenheit, to allow my girlfriend to use the system.

Right now the system is working.  I'm still getting checksum errors at about half the rate.

Code:
Circuit:
* Ethernet shield attached to pins 10, 11, 12, 13
*  Sensors:  DHT22 dataline connected to pin 7.  Suggested 4.7k Pull-up used
              Analog Pin 0 is a photocell to detect light levels
              Analog Pin 1 is a motion sensor

* Based on code:
* Created 22 April 2011
* By Jeffrey Sun
* http://code.google.com/p/pachubelibrary/
* and
* robtillart
* http://arduino.cc/forum/index.php/topic,58531.0.html
* http://arduino.cc/playground/Main/DHTLib

*/
#include <dht.h>
#include "ERxPachube.h"
#include <Ethernet.h>
#include <SPI.h>

dht DHT;
#define DHT22_PIN 7
byte mac[] = { 0x90, 0xA2, 0xDA, 0x00, 0x21, 0xE3 };
byte ip[] = { 192, 168, 1, 20   };                  // no DHCP so we set our own IP address

float TempC = (DHT.temperature, 1);
float Humidity =(DHT.humidity, 1);
float TempF;
float OldTemp = TempF;
float OldHumidity = Humidity;

#define PACHUBE_API_KEY "Your API Key HERE" // fill in your API key PACHUBE_API_KEY
#define PACHUBE_FEED_ID 34665 // fill in your feed id

ERxPachubeDataOut dataout(PACHUBE_API_KEY, PACHUBE_FEED_ID);

void PrintDataStream(const ERxPachube& pachube);

void setup() {

Serial.begin(9600);
Ethernet.begin(mac, ip);

dataout.addData(0);
dataout.addData(1);
dataout.addData(2);
        dataout.addData(3);
}

void loop() {

Serial.println("+++++++++++++++++++++++++++++++++++++++++++++++++");
float fSensorData = 15.23;
        int chk = DHT.read22(DHT22_PIN);
        switch (chk)
        {
          case 0:  Serial.print("OK,\t"); TempC = (DHT.temperature); Humidity = (DHT.humidity); break;
          case -1: Serial.print("Checksum error,\t"); break;
          case -2: Serial.print("Time out error,\t"); break;
          default: Serial.print("Unknown error,\t"); break;
          }
        // DISPLAY DATA
        //Temp = (DHT.temperature, 1);
        //Humidity = (DHT.humidity, 1);
        //int(Temp);
        //int(Humidity);
        //Serial.print(Temp);
        //Serial.print(",\t");
        //Serial.println(Humidity);
        TempF = float((TempC * float(1.8))+32);
        //Serial.print(DHT.humidity, 1);
        //Serial.print(",\t");
        //Serial.println(TempC);
        //Serial.println(TempF);
       
dataout.updateData(0, analogRead(0));
dataout.updateData(1, analogRead(1));
//dataout.updateData(2, (DHT.temperature,1));
        //dataout.updateData(3, (DHT.humidity,1));
        dataout.updateData(2, TempF);
        dataout.updateData(3, Humidity);
int status = dataout.updatePachube();

Serial.print("sync status code <OK == 200> => ");
Serial.println(status);

PrintDataStream(dataout);
        OldTemp = TempF;
        OldHumidity = Humidity;
delay(30000);
}

void PrintDataStream(const ERxPachube& pachube)
{
unsigned int count = pachube.countDatastreams();
Serial.print("data count=> ");
Serial.println(count);

Serial.println("<id>,<value>");
for(unsigned int i = 0; i < count; i++)
{
Serial.print(pachube.getIdByIndex(i));
Serial.print(",");
Serial.print(pachube.getValueByIndex(i));
Serial.println();
}
}
Logged

Global Moderator
Netherlands
Offline Offline
Shannon Member
*****
Karma: 222
Posts: 13867
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


The statement "float TempC = (DHT.temperature, 1); "  makes little sense,
You copied it from :   Serial.println(DHT.temperature, 1);    where it means    print the float DHT.temperature with one decimal  You cannot copy that into an assigment,


Here a patched (& stripped) version of your code, not tried as I don't have the pachube lib and sensor nearby to rebuild your sketch.
Let me know how it works...
Code:
#include <dht.h>
#include "ERxPachube.h"
#include <Ethernet.h>
#include <SPI.h>

dht DHT;
#define DHT22_PIN 7
byte mac[] = {
  0x90, 0xA2, 0xDA, 0x00, 0x21, 0xE3 };
byte ip[] = {
  192, 168, 1, 20   };                  // no DHCP so we set our own IP address

float TempC = 0;
float Humidity = 0;
float TempF = 0;
float OldTemp = 0;
float OldHumidity = 0;

#define PACHUBE_API_KEY "Your API Key HERE" // fill in your API key PACHUBE_API_KEY
#define PACHUBE_FEED_ID 34665 // fill in your feed id

ERxPachubeDataOut dataout(PACHUBE_API_KEY, PACHUBE_FEED_ID);

void PrintDataStream(const ERxPachube& pachube);

void setup()
{
  Serial.begin(9600);
  Ethernet.begin(mac, ip);

  dataout.addData(0);
  dataout.addData(1);
  dataout.addData(2);
  dataout.addData(3);
}

void loop() {

  Serial.println("+++++++++++++++++++++++++++++++++++++++++++++++++");
  float fSensorData = 15.23;
  int chk = DHT.read22(DHT22_PIN);
  switch (chk)
  {
  case 0: 
    Serial.print("OK,\t");
    TempC = DHT.temperature;
    Humidity = DHT.humidity;
    break;
  case -1:
    Serial.print("Checksum error,\t");
    break;
  case -2:
    Serial.print("Time out error,\t");
    break;
  default:
    Serial.print("Unknown error,\t");
    break;
  }
 
  TempF = float((TempC * float(1.8))+32);

  dataout.updateData(0, analogRead(0));
  dataout.updateData(1, analogRead(1));
  dataout.updateData(2, TempF);
  dataout.updateData(3, Humidity);
 
  int status = dataout.updatePachube();

  Serial.print("sync status code <OK == 200> => ");
  Serial.println(status);

  PrintDataStream(dataout);
  OldTemp = TempF;
  OldHumidity = Humidity;
  delay(30000);
}

void PrintDataStream(const ERxPachube& pachube)
{
  unsigned int count = pachube.countDatastreams();
  Serial.print("data count=> ");
  Serial.println(count);

  Serial.println("<id>,<value>");
  for(unsigned int i = 0; i < count; i++)
  {
    Serial.print(pachube.getIdByIndex(i));
    Serial.print(",");
    Serial.print(pachube.getValueByIndex(i));
    Serial.println();
  }
}

Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

0
Offline Offline
Newbie
*
Karma: 0
Posts: 35
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

robtillaart,
Thank you very much!
I'm in the process of trying to reduce the number of erroneous readings with the DHT22 sensor.  It seems that a 1 in 10 error rate is something to actually shoot for.  Some of my test runs are scoring an error rate of closer to 4 in 10 or higher.

Has anyone had any success reducing the error rate with this sensor?  I've placed the filter capacitor across the power and ground pins, but that didn't seem to have much of an effect.
Logged

0
Offline Offline
Newbie
*
Karma: 0
Posts: 35
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

More of an update:
I added in batch of code that records how often the system is getting Checksum errors.  I then left the system running while I went to sleep.  Lo and Behold, the error rate is consistently 45%, and I'm frequently getting abberant readings of ~55f (~12c).  The room is clearly not that cold.

I know you're not supposed to check the sensor more often than every 2 seconds.  I rewrote robtillaart's code a little bit (Which is like having a 4th grader trying to follow Da Vinci, his code is much more succinct):
Code:
#include <dht.h>
#include "ERxPachube.h"
#include <Ethernet.h>
#include <SPI.h>

dht DHT;
#define DHT22_PIN 7
byte mac[] = {
  0x90, 0xA2, 0xDA, 0x00, 0x21, 0xE3 };
byte ip[] = {
  192, 168, 1, 20   };                  // no DHCP so we set our own IP address

float TempC = 0;
float Humidity = 0;
float TempF = 0;
float OldTemp = 0;
float OldHumidity = 0;
float error = 0;
float run = 0;
float errorPerc = 0;

#define PACHUBE_API_KEY "Your API Here" // fill in your API key PACHUBE_API_KEY
#define PACHUBE_FEED_ID 34665 // fill in your feed id

ERxPachubeDataOut dataout(PACHUBE_API_KEY, PACHUBE_FEED_ID);

void PrintDataStream(const ERxPachube& pachube);

void setup()
{
  Serial.begin(9600);
  Ethernet.begin(mac, ip);

  dataout.addData(0);
  dataout.addData(1);
  dataout.addData(2);
  dataout.addData(3);
}

void loop() {

  Serial.println("+++++++++++++++++++++++++++++++++++++++++++++++++");
  float fSensorData = 15.23;
  int chk = DHT.read22(DHT22_PIN);
  delay(10000);
  switch (chk)
  {
  case 0: 
    Serial.print("OK,\t");
    TempC = DHT.temperature;
    //Humidity = DHT.humidity;
    break;
  case -1:
    Serial.print("Checksum error,\t");
    error = error +1;
    break;
  case -2:
    Serial.print("Time out error,\t");
    break;
  default:
    Serial.print("Unknown error,\t");
    break;
  }
 
  TempF = float((TempC * float(1.8))+32);
  if (TempF > 150)
  {
    TempF = OldTemp;
  }
  delay(20000);
  int chk2 = DHT.read22(DHT22_PIN);
  delay(10000);
  switch (chk2)
  {
  case 0: 
    Serial.print("OK,\t");
    //TempC = DHT.temperature;
    Humidity = DHT.humidity;
    break;
  case -1:
    Serial.print("Checksum error,\t");
    error = error + 1;
    break;
  case -2:
    Serial.print("Time out error,\t");
    break;
  default:
    Serial.print("Unknown error,\t");
    break;
  }
  if (Humidity > 101)
  {
    Humidity = OldHumidity;
  }
 

  dataout.updateData(0, analogRead(0));
  dataout.updateData(1, analogRead(1));
  dataout.updateData(2, TempF);
  dataout.updateData(3, Humidity);
 
  int status = dataout.updatePachube();

  Serial.print("sync status code <OK == 200> => ");
  Serial.println(status);

  PrintDataStream(dataout);
  if (TempF < 150)
  {
    OldTemp = TempF;
  }
  if (Humidity < 101)
  {
    OldHumidity = Humidity;
  }
 
  run = run+2;
  errorPerc = error / run;
  Serial.print(errorPerc);
  Serial.println("% errors");
  delay(20000);
}

void PrintDataStream(const ERxPachube& pachube)
{
  unsigned int count = pachube.countDatastreams();
  Serial.print("data count=> ");
  Serial.println(count);

  Serial.println("<id>,<value>");
  for(unsigned int i = 0; i < count; i++)
  {
    Serial.print(pachube.getIdByIndex(i));
    Serial.print(",");
    Serial.print(pachube.getValueByIndex(i));
    Serial.println();
  }
}

I'm trying to send information my environmental conditions to Pachube every minute.  That's the goal.
I'm wondering about the requests to the sensor.  The
int chk = DHT.read22(DHT22_PIN);
and subsequent "case" check, is that a request from the sensor?
When I'm asking the sensor for the current humidity and temperature, are those two different requests?  Should I space these out as much as possible?  (This is what I did in the code above).
Or does the
int chk = DHT.read22(DHT22_PIN);
request call all the sensor information, and load it into the Arduino memory, waiting for the DHT.temperature and DHT.humidity calls?

Does anyone else have a similar error rate?  That's what I'm really trying to drive down.
Logged

Global Moderator
Netherlands
Offline Offline
Shannon Member
*****
Karma: 222
Posts: 13867
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


int chk = DHT.read22(DHT22_PIN);

The read22() call tries to read data from the sensor and fills the variables DHT.temperature and DHT.humidity. The return value tells if something went wrong during that "exercise". Some people work with the "good weather" scenario and leave out all the checks, that's a design choice.

Quote
When I'm asking the sensor for the current humidity and temperature, are those two different requests?
NO, if you do a read22() both temperature and humidity are read. They can be obtained by reading the members DHT.temperature and DHT.humidity

Quote
Or does the
int chk = DHT.read22(DHT22_PIN);
request call all the sensor information, and load it into the Arduino memory, waiting for the DHT.temperature and DHT.humidity calls?
Yes, if you dive into the code of the library (don't be afraid smiley-wink , you see that temp and humidity are both filled in the read22() call.

MY errorrate with this sensor was definitely lower, no figures at hand.
Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

0
Offline Offline
Newbie
*
Karma: 0
Posts: 35
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I've posted on the retailer's website.  I'll let you folks know what develops.
Thanks again!
Logged

Offline Offline
Newbie
*
Karma: 0
Posts: 1
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


Here's my first pass: http://arduino-info.wikispaces.com/TemperatureHumidity  PLEASE critique / comment!!


Hi Terry, i´m new with Arduino and my first project is building a temperature-regulator. just i see your project and take parts from your code, but i can not see negative values on my display. have you got an idea, which part i must change? Sorry, i´m newbie and my english is not the best, but i hope, you or everyone can help...

thank you

olli

Code:

/*
Basierend auf einen Artikel auf dieser Seite:
http://arduino-info.wikispaces.com/PROJECT-Temp-Humidity-Display

den aktuellen Stand findest Du hier:
http://alturl.com/rpods
*/
 
/*-----( Import needed libraries )-----*/
#include <dht11.h>
#include <Wire.h>
#include <LiquidCrystal.h>
/*-----( Declare objects )-----*/
LiquidCrystal lcd(8, 9, 4, 5, 6, 7); //##### DFRobot LCD Keypadshield V1.0
 // legt die pins auf dem shield fest

/* begin des tastatur-bereichs */
int lcd_key = 0; // legt nutzung der tasten fest und dann die tasten selber
int adc_key_in = 0;
#define btnRIGHT 0
#define btnUP 1
#define btnDOWN 2
#define btnLEFT 3
#define btnSELECT 4
#define btnNONE 5
/* ab hier: einlesen der werte der tasten (wiederstands gebilde mit
unterschiedlichen spannungswerten zu jeder taste...*/

int read_LCD_buttons()
 {
 adc_key_in = analogRead(0); // read the value from the sensor
 // my buttons when read are centered at these valies: 0, 144, 329, 504, 741
 // we add approx 50 to those values and check to see if we are close
 if (adc_key_in > 1000) return btnNONE; // We make this the 1st option for speed reasons
since it will be the most likely result
 if (adc_key_in < 50) return btnRIGHT;
 if (adc_key_in < 195) return btnUP;
 if (adc_key_in < 380) return btnDOWN;
 if (adc_key_in < 555) return btnLEFT;
 if (adc_key_in < 790) return btnSELECT;
 return btnNONE; // when all others fail, return this...
 }
/* das wars mit dem tastatur-bereich */

dht11 DHT11;
/*-----( Declare Constants, Pin Numbers )-----*/
#define DHT11PIN 2

float alarmwert (20);
 
void setup() /*----( SETUP: RUNS ONCE )----*/
{
 Serial.begin(9600);
 lcd.begin(16,2); //##### Display Size for DFRobot LCD Keypadshield V1.0
 lcd.home ();
 lcd.println ("Olliduino "); //##### schreibe willkommensnachricht und springe eine zeile weiter
 lcd.setCursor (0,1);
 lcd.print ("2011 by olli "); //##### schreibe willkommensnachricht
 lcd.home ();
 delay(3000);
 lcd.clear ();
 
}/*--(end setup )---*/
 

void loop() /*----( LOOP: RUNS CONSTANTLY )----*/
{

 // digitalWrite(13, HIGH);

 
 int chk = DHT11.read(DHT11PIN);
 
 Serial.println("---------------------------"); //der Lesbarkeit erstmal eine Zeile
 switch (chk) // teste, ob ueberhaupt daten fliessen
 {
 case 0: Serial.println("DHT11 ist OK");
 Serial.print ("gelieferter Wert: ");
 Serial.println ((float)DHT11.temperature,1);
 break;
 case -1: Serial.println("Checksum error"); break;
 case -2: Serial.println("Time out error"); break;
 default: Serial.println("Unknown error"); break;
 }
Serial.print((float)alarmwert, 1);
 Serial.println("C Darunter-Gibt-es-ALARM-Temperatur");
 Serial.print((float)DHT11.temperature,1);
 Serial.println("C IST-Temperatur");
if ( DHT11.temperature < alarmwert )
 {
 digitalWrite(13, HIGH);
 Serial.println("### !!! Alarm erreicht !!! ###");
 lcd.setCursor (15,0); //##### schreibe ab zeichen 14 in zeile 1 (zeile 1 ist gleich 0)
 lcd.print("!");
 lcd.setCursor (0,1);
 }
else
 {
 digitalWrite(13, LOW);
 Serial.println("Alarm nicht erreicht, alles OK");
 lcd.setCursor (15,0); //##### schreibe ab zeichen 14 in zeile 1 (zeile 1 ist gleich 0)
 lcd.print("*");
 lcd.setCursor (0,1);
 }

 
 //lcd.noAutoscroll();
 lcd.setCursor (0,1);
 lcd.print(alarmwert,0);
 lcd.print("Cs ");
 lcd.print((float)DHT11.temperature,1);
 lcd.print("Ci ");
 lcd.print((float)DHT11.humidity,1);
 lcd.print("%");

 digitalWrite(13, LOW);
 
 delay(1000);
 
 
 
 
 // jetzt lesen wir noch die tasten ein und machen was draus
 
 lcd_key = read_LCD_buttons(); // read the buttons
switch (lcd_key) // depending on which button was pushed, we perform an action
 {
 case btnRIGHT:
 {
 lcd.setCursor (0,0);
 lcd.print("> ");
 break;
 }
 case btnLEFT:
 {
 lcd.setCursor (0,0);
 lcd.print("<");
 break;
 }
 case btnUP:
 {
 alarmwert = alarmwert + 1;
 lcd.setCursor (0,0);
 lcd.print("^");
 break;
 }
 case btnDOWN:
 {
 alarmwert = alarmwert - 1;
 lcd.setCursor (0,0);
 lcd.print("v");
 break;
 }
 case btnSELECT:
 {
 lcd.setCursor (0,0);
 lcd.print("*");
 break;
 }
 case btnNONE:
 {
 lcd.setCursor (0,0);
 lcd.print(" ");
 break;
 }
 }
 
 
 
 
 
 
 
 
 
 
}
/* --(end main loop )-- */

Logged

Global Moderator
Netherlands
Offline Offline
Shannon Member
*****
Karma: 222
Posts: 13867
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


updated the code to support Arduino 1.0 - as allways comments still welcome
Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

0
Offline Offline
Newbie
*
Karma: 0
Posts: 2
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi Rob,
Thank you so much for writing such an easy to use library!
I wanted to ask you a question if I may -
I'm using the DHT-11,
I tried supplying it with different voltages (3V, 3.3V, 5V - using the
Arduino Uno's 3V,5V and the Arduino Fio's 3.3V power supply)
and for each voltage there are different readings for the temperature and humidity (a
very big difference between 3V and 5V).
what is the correct voltage that it should be supplied with?
(or  is there a way to work around this?)
according to the datasheet it can be supplied with 3V - 5.5V.

thanks!
Logged

Global Moderator
Netherlands
Offline Offline
Shannon Member
*****
Karma: 222
Posts: 13867
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
I wanted to ask you a question if I may -

you may,

Quote
I tried supplying it with different voltages (3V, 3.3V, 5V - using the
Arduino Uno's 3V,5V and the Arduino Fio's 3.3V power supply)
and for each voltage there are different readings for the temperature and humidity (a
very big difference between 3V and 5V).
what is the correct voltage that it should be supplied with?Ac

As you say according to the datasheet, any voltage between 3 and 5.5V should work. I only can confirm that the readings makes good sense at 5Volt.

Quote
(or  is there a way to work around this?)
External powersupply for the sensor? does also make sense if the sensor is a bit further away, long wires.


If you use 3.5 volt and you take longer delays between the readings, does the accuracy of the reading increase?
Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

Offline Offline
Newbie
*
Karma: 0
Posts: 2
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I just wanted to say THANK YOU for all of the work! I just received a Freetronics Eleven and the DHT22 sensor. I tried the Library suggested, but just kept getting error during the compile process. And then I found your tutorial!!! Although it took me a bit to figure out how to create the Library from your work, once I did, everything started working. Now I am trying to figure out how to combine the Dew Point and C to F conversion from the DHT11 sketch with the DHT22 sketch so I can have the most information from just the one sketch.

Thanks again,
Logged

Potsdam
Offline Offline
Newbie
*
Karma: 0
Posts: 1
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi all,
At first I want to thank you for the library. Very nice and succint.

However, I noticed that in about 50% of all cases I'm getting a checksum error. This happens both, using 3.3V or 5V power supply. 
Does anyone now whether this is a hardware problem (low cost sensor?) or a timing problem while retrieving the data from the sensor?
I read that someone else also had this problem. Any solution? Typical situation :

DHT22,    Checksum error,   48.7,   1665.4
DHT22,    Checksum error,   48.7,   1665.4
DHT22,    Checksum error,   48.1,   846.2
DHT22,    Checksum error,   48.1,   846.2
DHT22,    OK,   48.5,   27.0
DHT22,    Checksum error,   48.4,   846.2
DHT22,    OK,   48.5,   27.0
DHT22,    Checksum error,   48.4,   846.2
DHT22,    OK,   48.5,   27.0
DHT22,    OK,   48.3,   27.0

Thanks for any help!
Logged

Global Moderator
Netherlands
Offline Offline
Shannon Member
*****
Karma: 222
Posts: 13867
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
Any solution?
You might need a pull up resistor (eg 4K) between +5V and the dataline.

How long is the line between the arduino and the sensor?

Rob
Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

Pages: 1 [2] 3 4 ... 8   Go Up
Jump to: