amc2022:grouph:dht22_humidity_temperature_sensor
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amc2022:grouph:dht22_humidity_temperature_sensor [2022/08/25 23:00] – gustavo001 | amc2022:grouph:dht22_humidity_temperature_sensor [2022/08/30 18:16] – gustavo001 | ||
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- | [[Data]]http:// | ||
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- | B = Material resistive value between two predetermined temperatures | + | B = Material resistive value between two predetermined temperatures\\ |
- | T1 = Base point temperature, | + | T1 = Base point temperature, |
- | T2 = Second temperature point, for example 100o C, and in Kelvin 100o C + 273.15 = 373.15K | + | T2 = Second temperature point, for example 100o C, and in Kelvin 100o C + 273.15 = 373.15K\\ |
- | R1 = Thermistors resistance at temperature T1 in Ohms | + | R1 = Thermistors resistance at temperature T1 in Ohms\\ |
- | R1 = Thermistors resistance at temperature T2 in Ohms | + | R1 = Thermistors resistance at temperature T2 in Ohms\\ |
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{{ : | {{ : | ||
- | Source : https:// | + | |**//Figure #//** Graph showing the Relationship between resistance and temperature. |
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|**//Figure #//** DHT22 Schematics. Source: https:// | |**//Figure #//** DHT22 Schematics. Source: https:// | ||
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+ | ====Signal ==== | ||
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+ | To read the data obtained by the module a protocol has to be observed. This protocol will function as an activation key that initiative the module, to send the information back to MCU and finalize the process. | ||
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+ | - The micro controller sends a start signal for 500 microseconds | ||
+ | - The micro controller sends a HIGH logic 1 Signal | ||
+ | - DHT22 responds by pulling the bus low for 80 microseconds | ||
+ | - DHT22 pulls the bus HIGH for 80 microseconds. | ||
+ | - DHT22 pulls the bus LOW again. | ||
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+ | Once the right sequence of the signal has been completed then DHT22 will start sending the information regarding both Temperature and Humidity. | ||
+ | Transmission of information is done through two set-ups called Logics. | ||
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+ | - 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:// | ||
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+ | {{ : | ||
+ | |**//Figure #//** DHT22 Logic Signal formation. Source: https:// | ||
====Data ==== | ====Data ==== | ||
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**_1_**000 0000 0110 0101, this means that the temperature is negative, therefore T = -10.1 °C((https:// | **_1_**000 0000 0110 0101, this means that the temperature is negative, therefore T = -10.1 °C((https:// | ||
+ | In Figure # down below, we can see the whole siganling process between ESP32 and DHT22. | ||
+ | {{ : | ||
+ | |**//Figure #//** DHT22 bus transmission. Source: https:// | ||
+ | ====Code==== | ||
- | | + | ====Results==== |
amc2022/grouph/dht22_humidity_temperature_sensor.txt · Last modified: 2022/09/09 17:22 by gustavo001