Differences

This shows you the differences between two versions of the page.

--- amc2022:grouph:dht22_humidity_temperature_sensor [2022/08/30 18:04] – gustavo001
+++ amc2022:grouph:dht22_humidity_temperature_sensor [2022/09/09 17:22] (current) – gustavo001
@@ Line 3: / Line 3: @@
-[[Data]]http://example.com|External Link
@@ Line 31: / Line 29: @@
 {{ :amc2022:grouph:ntc_themistor2.png?nolink&400 |}}
-Source : https://www.thomasnet.com/articles/automation-electronics/what-is-a-thermistor-and-how-does-it-work/
+|**//Figure #//** Graph showing the Relationship between resistance and temperature. Source : https://www.thomasnet.com/articles/automation-electronics/what-is-a-thermistor-and-how-does-it-work/|
 ===Humidity===
+Humidity determines the amount of moisture or water content in the air. Humidity can affect the health of an individual because the density of the air combined with the temperature can make breathing more difficult, also lung infection rates can be higher where relative humidity is higher, and people with respiratory afflictions such as COPD and asthma are more vulnerable to flare-ups and complications ((Arundel, A V et al. “Indirect health effects of relative humidity in indoor environments.” Environmental health perspectives vol. 65 (1986): 351-61. doi:10.1289/ehp.8665351)) therefore maintaining good levels of humidity indoors is beneficial for the overall health of the people living there.
+Humidity can be understood through the following terms: Absolute humidity, Relative humidity and Dew point.
+**Absolute humidity** defines the amount of moisture in air independent of temperature. Higher absolute humidity establishes that there is more water vapor in the air per unit volume, while in lower absolute humidity the air is holding less water vapor per unit volume.
+**Relative humidity** is a percentage representing the ratio between the absolute humidity content relative to the maximum moisture content possible at a predetermined temperature and atmospheric pressure.
+**Dew point** declares the temperature at which air has to be cooled in order to achieve 100% relative humidity.((https://www.thomasnet.com/articles/instruments-controls/all-about-humidity-sensors/))
+Amongst the various types of humidity sensors, the DHT22 module relies on the principle of **Capacitive humidity**, in it the design is built around measuring relative humidity.
+This design involves the use of an electrical conductivity sensor in the form of a layering of two electrodes separated by a moisture holding substrate material, as shown in Fig #. the dielectric material is specifically hygroscopic. With the absorption of moisture from the air, the dialectric constant increases, increasing the capacitance of the sensor. Since the change in the dialectric constant is directly proportional to the value of the relative humidity, a measurement of the change in capacitance will yield the relative humidity level. **Resistive humidity** will employ the same design with two electrodes separated by the gygroscopic conductive layer. The resistivity of the conductive material will vary inversely with the amount of moisture that is absorbed, higher absorption of water vapor will result in higher conductivity or lower resistivity. ((https://www.thomasnet.com/articles/instruments-controls/all-about-humidity-sensors/))
+The module converts the data into digital output for the micro controller which with the predetermined values established by the library DHT.h decodes the data and gives out the Relative humidity.
 {{ :amc2022:grouph:dht22_humidity_sensor.png?nolink&400 |}}
@@ Line 87: / Line 96: @@
   - Logic 1 is a 48 to 55 microsecond LOW  pulse followed by a 68 to 75 microsecond HIGH pulse.
   - Logic 0 is a 48 to 55 microsecond LOW pulse followed by a 22 to 30 microsecond HIGH pulse. ((https://www.teachmemicro.com/how-dht22-sensor-works/))
+{{ :amc2022:grouph:logic_1_0_dht22.png?nolink&200 |}}
+|**//Figure #//** DHT22 Logic Signal formation. Source: https://www.teachmemicro.com/how-dht22-sensor-works///|
 ====Data ====
@@ Line 129: / Line 142: @@
 **_1_**000 0000 0110 0101, this means that the temperature is negative, therefore T = -10.1 °C((https://www.researchgate.net/publication/312403569_How_to_Use_the_DHT22_Sensor_for_Measuring_Temperature_and_Humidity_with_the_Arduino_Board)).
+In Figure # down below, we can see the whole siganling process between ESP32 and DHT22.
+{{ :amc2022:grouph:data_transmission_dht22.png?nolink&900 |}}
+|**//Figure #//** DHT22 bus transmission. Source: https://www.teachmemicro.com/how-dht22-sensor-works///|
-====Code====
-====Results====