DHT11 Humidity &
Temperature Sensor
D-Robotics UK (www.droboticsonline.com)
DHT11 Temperature & Humidity Sensor features a
temperature & humidity sensor complex with a
calibrated digital signal output.
D-Robotics
7/30/2010
DHT 11 Humidity & Temperature
Sensor
1. Introduction
This DFRobot DHT11 Temperature & Humidity Sensor features a temperature & humidity sensor
complex with a calibrated digital signal output. By using the exclusive digital-signal-acquisition
technique and temperature & humidity sensing technology, it ensures high reliability and
excellent long-term stability. This sensor includes a resistive-type humidity measurement
component and an NTC temperature measurement component, and connects to a high-
performance 8-bit microcontroller, offering excellent quality, fast response, anti-interference
ability and cost-effectiveness.
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Each DHT11 element is strictly calibrated in the laboratory that is extremely accurate on
humidity calibration. The calibration coefficients are stored as programmes in the OTP memory,
which are used by the sensor’s internal signal detecting process. The single-wire serial interface
makes system integration quick and easy. Its small size, low power consumption and up-to-20
meter signal transmission making it the best choice for various applications, including those
most demanding ones. The component is 4-pin single row pin package. It is convenient to
connect and special packages can be provided according to users’ request.
2. Technical Specifications:
Overview:
Item
DHT11
Measurement Humidity
Range
Accuracy
20-90%RH
±5％RH
0-50
℃
Temperature
Accuracy
±2℃
Resolution
1
Package
4 Pin Single
Row
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Detailed Specifications:
Parameters
Humidity
Resolution
Repeatability
Accuracy
Conditions
Minimum
1%RH
Typical
1%RH
8 Bit
±1%RH
±4%RH
Maximum
1%RH
25℃
0-50℃
Interchangeability
Fully Interchangeable
Measurement
30%RH
0℃
Range
20%RH
25℃
20%RH
50℃
Response Time
1/e(63%)25℃， 6 S
(Seconds)
1m/s Air
Hysteresis
Long-Term
Typical
Stability
Temperature
Resolution
1℃
8 Bit
Repeatability
Accuracy
±1℃
Measurement
0℃
Range
Response Time
1/e(63%)
6S
(Seconds)
±5%RH
90%RH
90%RH
80%RH
15 S
10 S
±1%RH
±1%RH/year
1℃
8 Bit
±1℃
1℃
8 Bit
±2℃
50℃
30 S
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3. Typical Application (Figure 1)
Figure 1 Typical Application
Note: 3Pin – Null; MCU = Micro-computer Unite or single chip Computer
When the connecting cable is shorter than 20 metres, a 5K pull-up resistor is recommended;
when the connecting cable is longer than 20 metres, choose a appropriate pull-up resistor as
needed.
4. Power and Pin
DHT11’s power supply is 3-5.5V DC. When power is supplied to the sensor, do not send any
instruction to the sensor in within one second in order to pass the unstable status. One
capacitor valued 100nF can be added between VDD and GND for power filtering.
5. Communication Process: Serial Interface (Single-Wire Two-Way)
Single-bus data format is used for communication and synchronization between MCU and
DHT11 sensor. One communication process is about 4ms.
Data consists of decimal and integral parts. A complete data transmission is
40bit,
and the
sensor sends
higher data bit
first.
Data format:
8bit integral RH data + 8bit decimal RH data + 8bit integral T data + 8bit decimal T
data + 8bit check sum. If the data transmission is right, the check-sum should be the last 8bit of
"8bit integral RH data + 8bit decimal RH data + 8bit integral T data + 8bit decimal T data".
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