Hi, I am connecting Grove Temp & Hum Sensor to XBee Carrier + Wifi Bee, I am using the library in the Wiki and use the example like this :
// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain
#include "DHT.h"
#define DHTPIN 2 // what pin we're connected to
// Uncomment whatever type you're using!
#define DHTTYPE DHT11 // DHT 11
//#define DHTTYPE DHT22 // DHT 22 (AM2302)
//#define DHTTYPE DHT21 // DHT 21 (AM2301)
// Connect pin 1 (on the left) of the sensor to +5V
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor
DHT dht(DHTPIN, DHTTYPE);
void setup() {
Serial.begin(9600);
Serial.println("DHTxx test!");
dht.begin();
}
void loop() {
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
float h = dht.readHumidity();
float t = dht.readTemperature();
// check if returns are valid, if they are NaN (not a number) then something went wrong!
if (isnan(t) || isnan(h)) {
Serial.println("Failed to read from DHT");
} else {
Serial.print("Humidity: ");
Serial.print(h);
Serial.print(" %\t");
Serial.print("Temperature: ");
Serial.print(t);
Serial.println(" *C");
}
}
but the result is :
DHTxx test!
Read failFailed to read from DHT
Humidity: 0.00 % Temperature: 0.00 *C
Humidity: 0.00 % Temperature: 0.00 *C
Humidity: 0.00 % Temperature: 0.00 *C
==============
and then I tried to use another code :
/* YourDuino.com Example Software Sketch
DHT11 Humidity and Temperature Sensor test
Credits: Rob Tillaart
http://arduino-direct.com/sunshop/index.php?l=product_detail&p=162
terry@yourduino.com */
/*-----( Import needed libraries )-----*/
#include <dht11.h>
/*-----( Declare objects )-----*/
dht11 DHT11;
/*-----( Declare Constants, Pin Numbers )-----*/
#define DHT11PIN 2
void setup() /*----( SETUP: RUNS ONCE )----*/
{
Serial.begin(9600);
Serial.println("DHT11 TEST PROGRAM ");
Serial.print("LIBRARY VERSION: ");
Serial.println(DHT11LIB_VERSION);
Serial.println();
}/*--(end setup )---*/
void loop() /*----( LOOP: RUNS CONSTANTLY )----*/
{
Serial.println("\n");
int chk = DHT11.read(DHT11PIN);
Serial.print("Read sensor: ");
switch (chk)
{
case 0: Serial.println("OK"); break;
case -1: Serial.println("Checksum error"); break;
case -2: Serial.println("Time out error"); break;
default: Serial.println("Unknown error"); break;
}
Serial.print("Humidity (%): ");
Serial.println((float)DHT11.humidity, 2);
Serial.print("Temperature (oC): ");
Serial.println((float)DHT11.temperature, 2);
Serial.print("Temperature (oF): ");
Serial.println(Fahrenheit(DHT11.temperature), 2);
Serial.print("Temperature (K): ");
Serial.println(Kelvin(DHT11.temperature), 2);
Serial.print("Dew Point (oC): ");
Serial.println(dewPoint(DHT11.temperature, DHT11.humidity));
Serial.print("Dew PointFast (oC): ");
Serial.println(dewPointFast(DHT11.temperature, DHT11.humidity));
delay(2000);
}/* --(end main loop )-- */
/*-----( Declare User-written Functions )-----*/
//
//Celsius to Fahrenheit conversion
double Fahrenheit(double celsius)
{
return 1.8 * celsius + 32;
}
//Celsius to Kelvin conversion
double Kelvin(double celsius)
{
return celsius + 273.15;
}
// dewPoint function NOAA
// reference: http://wahiduddin.net/calc/density_algorithms.htm
double dewPoint(double celsius, double humidity)
{
double A0= 373.15/(273.15 + celsius);
double SUM = -7.90298 * (A0-1);
SUM += 5.02808 * log10(A0);
SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;
SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;
SUM += log10(1013.246);
double VP = pow(10, SUM-3) * humidity;
double T = log(VP/0.61078); // temp var
return (241.88 * T) / (17.558-T);
}
// delta max = 0.6544 wrt dewPoint()
// 5x faster than dewPoint()
// reference: http://en.wikipedia.org/wiki/Dew_point
double dewPointFast(double celsius, double humidity)
{
double a = 17.271;
double b = 237.7;
double temp = (a * celsius) / (b + celsius) + log(humidity/100);
double Td = (b * temp) / (a - temp);
return Td;
}
/* ( THE END ) */
and the result is :
DHT11 TEST PROGRAM
LIBRARY VERSION: 0.3.2
Read sensor: Time out error
Humidity (%): 0.00
Temperature (oC): 0.00
Temperature (oF): 32.00
Temperature (K): 273.15
Dew Point (oC): nan
Dew PointFast (oC): nan
=====
I tried another code again from here :
#define dht11_pin 14 //Analog port 0 on Arduino Uno
//#define dht11_pin 54 //Analog port 0 on Arduino Mega2560
byte read_dht11_dat()
{
byte i = 0;
byte result=0;
for(i=0; i< 8; i++)
{
while (!digitalRead(dht11_pin));
delayMicroseconds(30);
if (digitalRead(dht11_pin) != 0 )
bitSet(result, 7-i);
while (digitalRead(dht11_pin));
}
return result;
}
void setup()
{
pinMode(dht11_pin, OUTPUT);
digitalWrite(dht11_pin, HIGH);
Serial.begin(9600);
Serial.println("Ready");
}
void loop()
{
byte dht11_dat[5];
byte dht11_in;
byte i;// start condition
digitalWrite(dht11_pin, LOW);
delay(18);
digitalWrite(dht11_pin, HIGH);
delayMicroseconds(1);
pinMode(dht11_pin, INPUT);
delayMicroseconds(40);
if (digitalRead(dht11_pin))
{
Serial.println("dht11 start condition 1 not met"); // wait for DHT response signal: LOW
delay(1000);
return;
}
delayMicroseconds(80);
if (!digitalRead(dht11_pin))
{
Serial.println("dht11 start condition 2 not met"); //wair for second response signal:HIGH
return;
}
delayMicroseconds(80);// now ready for data reception
for (i=0; i<5; i++)
{ dht11_dat[i] = read_dht11_dat();} //recieved 40 bits data. Details are described in datasheet
pinMode(dht11_pin, OUTPUT);
digitalWrite(dht11_pin, HIGH);
byte dht11_check_sum = dht11_dat[0]+dht11_dat[2];// check check_sum
if(dht11_dat[4]!= dht11_check_sum)
{
Serial.println("DHT11 checksum error");
}
Serial.print("Current humdity = ");
Serial.print(dht11_dat[0], DEC);
Serial.print("% ");
Serial.print("temperature = ");
Serial.print(dht11_dat[2], DEC);
Serial.println("C ");
delay(2000); //fresh time
}
the result :
Ready
dht11 start condition 1 not met
dht11 start condition 1 not met
dht11 start condition 1 not met
dht11 start condition 1 not met
dht11 start condition 1 not met
dht11 start condition 1 not met
I was wondering that the cause is the I/O pin, in both code above they use pin 2 but when I googling around I found that the code is for DHT11 like this :
pin 1 = VCC
pin 2 = Signal/Data
pin 3 = NC/Not Connected
pin 4 = Ground
not a Grove like I am using :
that's why the codes above use pin 2, so I tried to change it to pin 5 as discribed in Xbee Carrier Wiki, although I am not sure that pin 5 means D5 and pin 6 means D6 Grove Connector:
When using an RFBee, the following pinouts apply for using the arduino IDE
Pin 5 is the Grove connector for I/O - Yellow wire
Pin 6 is the Grove connector for I/O - White wire
and when I carefully look at the cable, everything is at the right place :
Cable Colour == Xbee Carrier == Grove Temp Hum
Yellow == D5 == SIG
White == D6 == NC
Red == VCC == VCC
Black == Ground == Ground
but the result is the same, timeout or communication failed
I also asked on "Question & Answer" section in Xbee Carrier product guide and Jacket Chueng answered :
Hi.You also need to add some code to the program,such as: pinMode(16, OUTPUT); digitalWrite(16, LOW).And more information you can refer to our wiki:Pin 16 may need to be driven low to provide enough power to the I/O Grove [via mosfet].
Answered by Jacket Chueng | 2013-04-07
anyone can give me some more detail what should I do? I am a newbie on Arduino and microcontroller, I just want to make a simple project and develop it later after this has been success.
Thank you.
#sorry for my bad english
