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- 9 

广州奥松电子有限公司 电话：

020-36042809 / 36380552 

www.aosong.com

 

=>Temperature=-26.6 degrees Celsius 

◎Peripheral reading steps 

Communication  between  the  host  and  the  sensor  reads  data  by  completing  the  following 

three steps. 

Step one: 

DHT12  After  power  up  (start  wait  2  Seconds  to  cross  the  unstable  condition  of  the 

sensor)Tested environment temperature and humidity data, and record data, sensor automatic 
hibernation.DHT12 The data because of the pull-up resistor has remained high, at this time DHT12 
的 SDA PIN is input, detect external signals. 

Step two: 

Hosting  by  SDA  Data  bus  output  low  level  and  low  level  for  at  least  200ms  Released  by 

bus,DHT12 Detects a bus free, issue 80µs Low level immediately 80µs High level signal, as shown 
below: 

 

图 17 Signal 

diagram

Step three: 

DHT12 After the response is sent immediately by the continuous serial data bus output 40 

Data host under the bus level receive 40 Bit data. 

Bit data"0"Format:50µs Low level plus 26-28µs High level; data"1"Format:50µs 

Low level plus 70µs High level; data"0", Bit data"1"Signal format shown in the 

following figure: 

 

图 18 Bit data"1"和"0"Format signal

 

Содержание DHT12

Страница 1: ...Digital temperature Product Product 超 Stan For more information ...

Страница 2: ...ommunication sequence the user can directly I2C Communication on the bus no additional wiring simple to use Two way switch users are free to choose easy to use should be a broad range of areas Products for the 4 Lead convenient connection provides special packages according to user needs Second the scope of application Heating ventilation and air conditioning Dehumidifier test and inspection equip...

Страница 3: ...elative humidity 5 2 Temperature 表 1 DHT12 Relative humidity tables 表 2 DHT12 Relative performance table Paramete rs Condit ions mi n ty p m ax W ork uni t Paramete rs Condit ions mi n ty p m ax Wo rk uni t Resolution 0 1 R H Resolution 0 1 Measuring range 20 95 R H 16 bit Precision 1 60 RH 5 R H Precision 25 0 5 1 此精度为出厂时检验时 传感器在 25 和 5V 条件下测试的精度指标 且只适合非冷凝环境 参数 条件 min typ max 单位 ...

Страница 4: ...changeable Hysteresis 0 5 R H Response time 1 e 63 20 S Drift 23 Typical value 0 5 RH yr Drift 0 1 y r 供电电压 2 7 5 5 5 V 功耗 4 休眠 30 µA 测量 800 µA 平均 150 µA 低电平输出电压 IOL5 0 300 mV 高电平输出电压 Rp 25 kΩ 90 100 VDD 低电平输入电压 下降 0 30 VDD 高电平输入电压 上升 70 100 VDD Rpu6 VDD 5V VIN VSS 1 4 7 10 kΩ 输出电流 开 8 mA 三 态 关 10 20 µA 采样周期 2 S 1 在 25 和 1m s 气流的条件下 达到一阶响应 63 所需要的时间 2 在挥发性有机混合物中数值可能会高一些 见说明书应用储存信息 3 此数值为 VDD 5 0V ...

Страница 5: ... the power supply voltage is 12V 表 3 DHT12 DC characteristics Seven interface definition 7 1 DHT12 Pin assignments 表 4 DHT12 Pin assignments 图 4 DHT12Wiring diagram 7 2 Power supply pins VDD GND DHT12 The supply voltage range 2 7V 5 5V 7 3 Serial clock input SCL SCL Pins are used for selection of the means of communication and I2C Communication clock line Dang SCL After power remained low indicati...

Страница 6: ...n mode when power on SCL Remained low for a single bus communication mode when power on SCL To maintain a high level I2C Communication mode Single main line single bus communication is fully compatible with the company s other products I2 C Communication in accordance with I2 C Standard protocol address can be directly linked to I2 C On the bus bus allowed only one product no additional wiring ope...

Страница 7: ... value 0x03 R Temperature scale 0x04 R Checksum Data refer to the single bus data processing sample I2C Interface attributes Must be in strict accordance with the following distribution specification otherwise the sensor does not work Communication protocol 图 13 I2C Communication protocolReading time ...

Страница 8: ...a single bus around 4 7KΩPull up resistor so that when the bus is idle by default high State Because they are the master slave relationship only when the host calls the sensor the sensor responds so host access must be strictly followed during single bus timing timing disorder if will not be able to correctly read data of temperature and humidity Single bus transfer data definitions SDA PIN for cl...

Страница 9: ...00011010 00000110 01100000 Humidity integral digits Humidity scale Temperature integer bit Temperature scale Check digit 00111000 00001000 00011010 00000110 01100000 Check digit receive data properly Humidity 00111000 Binary 56 Decimal 00001000 Binary 8 Decimal Humidity 56 8 RH Temperature 00011010 Binary 26 Decimal 00000110 Binary 6 Decimal Temperature 26 6 degrees Celsius Example two received 40...

Страница 10: ... has remained high at this time DHT12 的 SDA PIN is input detect external signals Step two Hosting by SDA Data bus output low level and low level for at least 200ms Released by bus DHT12 Detects a bus free issue 80µs Low level immediately 80µs High level signal as shown below 图 17 Signal diagramStep three DHT12 After the response is sent immediately by the continuous serial data bus output 40 Data ...

Страница 11: ...rcuit recommended cable length is shorter than the 20 Meter use 5 1K Pull up resistor is greater than 20 Meters lower the pullup resistor value according to actual situation 2 Each numerical readout of temperature and humidity is the result of the last measurement to get real time data need to read twice in a row but not recommended to read several times in succession each read sensor spacing is g...

Страница 12: ... Avoid long in the component condensation and dry environment as well as the environment A Salt spray B Acidic or oxidizing gases such as sulphur dioxide hydrochloric acid C Volatile organic solvents recommend gas storage environment Temperature 10 40 Humidity 60 RH The following 2 Effects of exposure to chemical substances in Induction of resistance humidity sensor layer affected by interference ...

Страница 13: ...e shell To reduce heat conduction sensors and other parts of the printed circuit board copper platingLayer should be as minimal as possible and to leave a gap between the two 4 Light effects Prolonged exposure to sunlight or strong ultraviolet radiation will decrease performance 5 Recovery processing Placed in extreme working conditions or chemical vapor sensors with the following handlers can be ...

Страница 14: ...ath or serious bodily injury the company will not be liable for the resulting personal injuries and deaths of all compensation and exemption from the managers and employees of the company and the subsidiary agents distributors any claims that may arise including all costs damages attorney fees and so on 12 quality assurance The company direct purchasers of its products for a period of 12 A month A...

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