Difference between revisions of "Component: Temp / Humidity (DHT22) (Environmental)"

Latest revision as of 10:25, 20 October 2023

Author	Matrix TSL
Version	1.2
Category	Environmental

Temp / Humidity (DHT22) component

The DHT22 temperature and humidity sensor is a popular sensor allowing the ambient temperature and relative humidity to be monitored digitally. Humidity Range = 0% - 100% +/- 2% Temperature Range = -40 - 80 Degrees C +/- 0.5 Degrees C

Component Source Code

Please click here to download the component source project: FC_Comp_Source_DHT22.fcfx

Please click here to view the component source code (Beta): FC_Comp_Source_DHT22.fcfx

Detailed description

No detailed description exists yet for this component

Examples

Example Program showing how to sample the DHT22 sensor and show the temperature and humidity on an LCD. DHT22 Example

Macro reference

GetHumidityFloat

	GetHumidityFloat
Gets the humidity returned by calling SampleSensor as a floating point number. If humidity is 15.8 % then this function would return 15.8.
- FLOAT	Return

GetHumidityReal

	GetHumidityReal
Gets the real number portion of the humidity returned by calling SampleSensor. If humidity is 15.8 % then this function would return 8.
- INT	Return

GetHumidityString

	GetHumidityString
Gets the humidity returned by calling SampleSensor as a string. If humidity is 15.8 % then this function would return "15.8".
- STRING	Return

GetHumidityWhole

	GetHumidityWhole
Gets the whole number portion of the humidity returned by calling SampleSensor. If humidity is 15.8 % then this function would return 15.
- INT	Return

GetTempFloat

	GetTempFloat
Gets the temperature returned by calling SampleSensor as a floating point number. If temperature is 15.8 degrees C then this function would return 15.8.
- FLOAT	Return

GetTempReal

	GetTempReal
Gets the real number portion of the temperature returned by calling SampleSensor. If temperature is 15.8 degrees C then this function would return 8.
- INT	Return

GetTempString

	GetTempString
Gets the temperature returned by calling SampleSensor as a string. If temperature is 15.8 degrees C then this function would return "15.8".
- STRING	Return

GetTempWhole

	GetTempWhole
Gets the whole number portion of the temperature returned by calling SampleSensor. If temperature is 15.8 degrees C then this function would return 15.
- INT	Return

SampleSensor

	SampleSensor
Communicates with the DHT22 sensor and receives the temperature and humidity readings. Returns 0 for success, 1 for no communication detected and 2 for checksum error.
- BYTE	Return

Property reference

	Properties
	SIG Pin
Microcontroller I/O Pin connected to the DHT11 sensor data pin.
	Use Checksum
The checksum value is used to ensure the data being received is correct. Yes = Only receive data if checksum is correct No = Ignore checksum
	Advanced Settings
	Clock Adjustment
On 8-bit PIC devices the timings can be a little tight as slower clock speeds and so we implement an adjustment factor to allow the sensor to function. Auto mode will attempt to automatically calculate a correct adjustment factor. Manual mode will allow you to set your own adjustment factor.

@@ Line 74: / Line 74: @@
 Example Program showing how to sample the DHT22 sensor and show the temperature and humidity on an LCD.
 {{Fcfile|DHT22_Example.fcfx|DHT22 Example}}
@@ Line 79: / Line 89: @@
 ==Macro reference==
+===GetHumidityFloat===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
 | width="10%" align="center" style="background-color:#D8C9D8;" align="center" | [[File:Fc9-comp-macro.png]]
-| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetTempWhole'''
+| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetHumidityFloat'''
 |-
-| colspan="2" | Gets the whole number portion of the temperature returned by calling SampleSensor. If temperature is 15.8 degrees C then this function would return 15.&nbsp;
+| colspan="2" | Gets the humidity returned by calling SampleSensor as a floating point number. If humidity is 15.8 % then this function would return 15.8.&nbsp;
 |-
 |-
-| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-s16-icon.png]] - INT
+| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-f32-icon.png]] - FLOAT
 | width="90%" style="border-top: 2px solid #000;" | ''Return''
 |}
+===GetHumidityReal===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
 | width="10%" align="center" style="background-color:#D8C9D8;" align="center" | [[File:Fc9-comp-macro.png]]
-| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetHumidityFloat'''
+| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetHumidityReal'''
 |-
-| colspan="2" | Gets the humidity returned by calling SampleSensor as a floating point number. If humidity is 15.8 % then this function would return 15.8.&nbsp;
+| colspan="2" | Gets the real number portion of the humidity returned by calling SampleSensor. If humidity is 15.8 % then this function would return 8.&nbsp;
 |-
 |-
-| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-f32-icon.png]] - FLOAT
+| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-s16-icon.png]] - INT
 | width="90%" style="border-top: 2px solid #000;" | ''Return''
 |}
+===GetHumidityString===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
 | width="10%" align="center" style="background-color:#D8C9D8;" align="center" | [[File:Fc9-comp-macro.png]]
-| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetTempString'''
+| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetHumidityString'''
 |-
-| colspan="2" | Gets the temperature returned by calling SampleSensor as a string. If temperature is 15.8 degrees C then this function would return "15.8".&nbsp;
+| colspan="2" | Gets the humidity returned by calling SampleSensor as a string. If humidity is 15.8 % then this function would return "15.8".&nbsp;
 |-
 |-
@@ Line 118: / Line 131: @@
+===GetHumidityWhole===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
 | width="10%" align="center" style="background-color:#D8C9D8;" align="center" | [[File:Fc9-comp-macro.png]]
-| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetHumidityString'''
+| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetHumidityWhole'''
 |-
-| colspan="2" | Gets the humidity returned by calling SampleSensor as a string. If humidity is 15.8 % then this function would return "15.8".&nbsp;
+| colspan="2" | Gets the whole number portion of the humidity returned by calling SampleSensor. If humidity is 15.8 % then this function would return 15.&nbsp;
 |-
 |-
-| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-string-icon.png]] - STRING
+| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-s16-icon.png]] - INT
 | width="90%" style="border-top: 2px solid #000;" | ''Return''
 |}
+===GetTempFloat===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
 | width="10%" align="center" style="background-color:#D8C9D8;" align="center" | [[File:Fc9-comp-macro.png]]
-| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetHumidityWhole'''
+| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetTempFloat'''
 |-
-| colspan="2" | Gets the whole number portion of the humidity returned by calling SampleSensor. If humidity is 15.8 % then this function would return 15.&nbsp;
+| colspan="2" | Gets the temperature returned by calling SampleSensor as a floating point number. If temperature is 15.8 degrees C then this function would return 15.8.&nbsp;
 |-
 |-
-| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-s16-icon.png]] - INT
+| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-f32-icon.png]] - FLOAT
 | width="90%" style="border-top: 2px solid #000;" | ''Return''
 |}
+===GetTempReal===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
@@ Line 157: / Line 173: @@
+===GetTempString===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
 | width="10%" align="center" style="background-color:#D8C9D8;" align="center" | [[File:Fc9-comp-macro.png]]
-| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetHumidityReal'''
+| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetTempString'''
 |-
-| colspan="2" | Gets the real number portion of the humidity returned by calling SampleSensor. If humidity is 15.8 % then this function would return 8.&nbsp;
+| colspan="2" | Gets the temperature returned by calling SampleSensor as a string. If temperature is 15.8 degrees C then this function would return "15.8".&nbsp;
 |-
 |-
-| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-s16-icon.png]] - INT
+| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-string-icon.png]] - STRING
 | width="90%" style="border-top: 2px solid #000;" | ''Return''
 |}
+===GetTempWhole===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
 | width="10%" align="center" style="background-color:#D8C9D8;" align="center" | [[File:Fc9-comp-macro.png]]
-| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''SampleSensor'''
+| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetTempWhole'''
 |-
-| colspan="2" | Communicates with the DHT22 sensor and receives the temperature and humidity readings. Returns 0 for success, 1 for no communication detected and 2 for checksum error.&nbsp;
+| colspan="2" | Gets the whole number portion of the temperature returned by calling SampleSensor. If temperature is 15.8 degrees C then this function would return 15.&nbsp;
 |-
 |-
-| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-u8-icon.png]] - BYTE
+| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-s16-icon.png]] - INT
 | width="90%" style="border-top: 2px solid #000;" | ''Return''
 |}
+===SampleSensor===
 {| class="wikitable" style="width:60%; background-color:#FFFFFF;"
 |-
 | width="10%" align="center" style="background-color:#D8C9D8;" align="center" | [[File:Fc9-comp-macro.png]]
-| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''GetTempFloat'''
+| width="90%" style="background-color:#D8C9D8; color:#4B008D;" | '''SampleSensor'''
 |-
-| colspan="2" | Gets the temperature returned by calling SampleSensor as a floating point number. If temperature is 15.8 degrees C then this function would return 15.8.&nbsp;
+| colspan="2" | Communicates with the DHT22 sensor and receives the temperature and humidity readings. Returns 0 for success, 1 for no communication detected and 2 for checksum error.&nbsp;
 |-
 |-
-| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-f32-icon.png]] - FLOAT
+| width="10%" align="center" style="border-top: 2px solid #000;" | [[File:Fc9-u8-icon.png]] - BYTE
 | width="90%" style="border-top: 2px solid #000;" | ''Return''
 |}