Grove - Temperature&Humidity Sensor

This temperature & humidity sensor provides a pre-calibrated digital output. A unique capacitive sensor element measures relative humidity and the temperature is measured by a negative temperature coefficient (NTC) thermistor. It has excellent reliability and long term stability. Please note that this sensor will not work for temperatures below 0 degree.

Model:SEN11301P

Features

Relative Humidity and temperature measurement
Full range temperature compensation Calibrated
Digital signal
Long term stability
Long transmission distance(>20m)
Low power consumption

Applications Ideas

Consumption product
Weather station
Humidity regulator
Air conditioner

Schematic

Specifications

Key Specification

Items	Min
PCB Size	2.0cm*4.0cm
Interface	2.0mm pitch pin header
IO Structure	SIG,VCC,GND,NC
ROHS	YES

Electronic Characterstics

Items	Conditions	Min	Norm	Max	Unit
VCC	-	3.3	-	5	Volts
Measuring Current Supply	-	1.3	-	2.1	mA
Average Current Supply	-	0.5	-	1.1	mA
Measuring Range	Humidity	20%	-	90%	RH
Measuring Range	Temperature	0	-	50	°C
Accuracy	Humidity	-	-	±5%	RH
Accuracy	Temperature			±2	°C
Sensitivity	Humidity		-	1%	RH
Sensitivity	Temperature			1	°C
Repeatability	Humidity			±1%	RH
Repeatability	Temperature			±1	°C
Long-term Stability				±1%	RH/year
Signal Collecting Period			2		S

Usage

When MCU sends a trigger signal, sensor will change from low power consumption mode to active mode. After the trigger signal sensor will send a response signal back to MCU, then 40 bit collected data is sent out and a new signal collecting is trigged.(Note that the 40 bit collected data which is sent from sensor to MCU is already collected before the trigger signal comes.) One trigger signal receives one time 40 bit response data from sensor. Single-bus data is used for communication between MCU and sensor.
The communication process is shown as below:

It costs 5mS for single time communication.The high-order bit of data sends out first. Signal Data is 40 bit, comprised of 16 bit humidity data, 16 bit temperature data and 8 bit checksum.The data format is:

8bits integer part of humidity+8bits decimal part of humidity
+8bits integer part of temperature+8bits decimal part of temperature
+8bits checksum.

Programming

Connect the Temperature and Humidity sensor to analog port A0.Then you can use the following programme to gain the temperature and humidity of the environment.(The code is for seeeduino only,if you use seeeduino mega you should change the code a little. See below, if you use seeeduino mega, you should change PINC to PINF, change DDRC to DDRF and change PORTC to PORTF)

#define DHT11_PIN 0      // ADC0
 
byte read_dht11_dat()
{
  byte i = 0;
  byte result=0;
  for(i=0; i< 8; i++){
 
 
    while(!(PINC & _BV(DHT11_PIN)));  // wait for 50us
    delayMicroseconds(30);
 
    if(PINC & _BV(DHT11_PIN)) 
      result |=(1<<(7-i));
    while((PINC & _BV(DHT11_PIN)));  // wait '1' finish
 
 
  }
  return result;
}
 
 
void setup()
{
  DDRC |= _BV(DHT11_PIN);
  PORTC |= _BV(DHT11_PIN);
 
  Serial.begin(9600);
 
  Serial.println("Ready");
}
 
void loop()
{
  byte dht11_dat[5];
  byte dht11_in;
  byte i;
  // start condition
  // 1. pull-down i/o pin from 18ms
  PORTC &= ~_BV(DHT11_PIN);
  delay(18);
  PORTC |= _BV(DHT11_PIN);
  delayMicroseconds(40);
 
  DDRC &= ~_BV(DHT11_PIN);
  delayMicroseconds(40);
 
  dht11_in = PINC & _BV(DHT11_PIN);
 
  if(dht11_in){
    Serial.println("dht11 start condition 1 not met");
    return;
  }
  delayMicroseconds(80);
 
  dht11_in = PINC & _BV(DHT11_PIN);
 
  if(!dht11_in){
    Serial.println("dht11 start condition 2 not met");
    return;
  }
  delayMicroseconds(80);
  // now ready for data reception
  for (i=0; i<5; i++)
    dht11_dat[i] = read_dht11_dat();
 
  DDRC |= _BV(DHT11_PIN);
  PORTC |= _BV(DHT11_PIN);
 
  byte dht11_check_sum = dht11_dat[0]+dht11_dat[1]+dht11_dat[2]+dht11_dat[3];
  // 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(dht11_dat[1], DEC);
  Serial.print("%  ");
  Serial.print("temperature = ");
  Serial.print(dht11_dat[2], DEC);
  Serial.print(".");
  Serial.print(dht11_dat[3], DEC);
  Serial.println("C  ");
 
  delay(2000);
}

Version Tracker

Revision	Descriptions	Release
Grove - Temp&Humi Sensor v1.0	Initial public release for Grove module	Jan 14, 2011

Resources

Temperature Humidity.zip

How to buy

Click here to buy: http://www.seeedstudio.com/depot/grove-temphumi-sensor-p-745.html?cPath=144_147.

Licensing

This documentation is licensed under the Creative Commons Attribution-ShareAlike License 3.0 Source code and libraries are licensed under GPL/LGPL, see source code files for details.

External Links

Links to external webpages which provide more application ideas, documents/datasheet or software libraries