Component: Temp / Humidity (DHT22) (Environmental)

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

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

Downloadable macro reference

	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.
[[File:]] -	Return

	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.
[[File:]] -	Return

	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

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

	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.
[[File:]] -	Return

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

	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

	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.
[[File:]] -	Return

	Initialise
Initialise the sensor configuration as set by the component properties
- VOID	Return

	Initialise
Stes up the I2C bus and initialises the termperature sensor ready for use.
- VOID	Return

	SimSetGyro
Allows the XYZ slider values to be set via the simulation
[[File:]] -	X
[[File:]] -	Y
[[File:]] -	Z
- VOID	Return

	UpdateAccelerometerData
Reads from the accelerometer and updates the local XYZ variables. Returns 1 for new data and 0 for no new data
- BYTE	Return

	SimSetCompass
Allows the XYZ slider values to be set via the simulation
[[File:]] -	X
[[File:]] -	Y
[[File:]] -	Z
- VOID	Return

	Read_Bearing
Reads the current sensor compass bearing based on degrees CW from magnetic north. Returns 0-359 where 0 = North, 90 = East, 180 = South, 270 = West Requires the ArcTan floating point function to be available to work correctly. Supported on AVR, 16-bit
- BYTE	NumSamples
The number of readings to base the bearing on
- UINT	Return

	Initialise
Sets up up the communication bus and initialises the accelerometer module. Returns 0 for success and > 0 for fail.
- BYTE	Return

	IOSetOutputPin
Sets the selected digital pin to an output and assigns the output state.
- BYTE	Pin
Range: 0-29
[[File:]] -	State
Range: 0-1
- VOID	Return

	UARTReceive
Receives a data byte from the UART. Recommend calling the UARTCheckRx function first to ensure data is available.
- BYTE	Channel
Channel Index: Range 0 - UART Bus Count - 1
- BYTE	Return

	ADCSampleAverage10
Reads the voltage present on an Analog pin as an 10-bit value range 0-1023. Performs the selected number of samples with the selected time in microseconds in between samples
- BYTE	ADCChannel
Range: 0, 3-7
- BYTE	SampleCount
Range: 1- 100
- BYTE	SampleDelay
Delay in us between each sample
- UINT	Return

	OneWireScanBus
Scans the one wire bus to detect all connected devices. Returns the number of one wire devices found.
- BYTE	Channel
Channel Index: Range 0 - I2C Bus Count - 1
- BYTE	Return

	SPIInitialise
Initialsie the SPI module ready for communications
- BYTE	Channel
Channel Index: Range 0 - SPI Bus Count - 1
- VOID	Return

	OneWireReceiveByte
Receives a byte from the one wire bus a bit at a time
- BYTE	Channel
Channel Index: Range 0 - I2C Bus Count - 1
- BYTE	Return

	I2CSend
Transmit a byte using the I2C bus
- BYTE	Channel
Channel Index: Range 0 - I2C Bus Count - 1
- BYTE	DataOut
[[File:]] -	Return

	UARTSend
Send a byte via the UART module
- BYTE	Channel
Channel Index: Range 0 - UART Bus Count - 1
- BYTE	Data
Data Byte to send. Range: 0-255
- VOID	Return

	OneWireGetDeviceCount
Returns the number of devices found by the last ScanBus operation.
- BYTE	Channel
Channel Index: Range 0 - I2C Bus Count - 1
- BYTE	Return

	PWMSetPrescaler
Sets the prescaler for the PWM output
- BYTE	Channel
Range: 0 - 11
- BYTE	Prescaler
- BYTE	Period
- VOID	Return

	PWMEnable
Enable a PWM output
- BYTE	Channel
Range: 0-11
- VOID	Return

	ADCSampleArray10
Reads the voltage present on an Analog pin as an 10-bit value range 0-1023 Performs the selected number of samples with the selected time in microseconds in between samples and returns each sample in a single packet
- BYTE	ADCChannel
Range: 0, 3-7
- BYTE	SampleCount
Range: 1- 32
- UINT	SampleDelay
Delay in us between each sample
- UINT	Samples
10-bit samples returned from the function
- VOID	Return

	ADCSampleAverage8
Reads the voltage present on an Analog pin as an 8-bit value range 0-255 Performs the selected number of samples with the selected time in microseconds in between samples
- BYTE	ADCChannel
Range: 0, 3-7
- BYTE	SampleCount
Range: 1- 100
- BYTE	SampleDelay
Delay in us between each sample
- BYTE	Return

	Initialise
Initialise the comms to the Arduino board ready for commands to be sent.
- VOID	Return

	PWMEnable
Allows pulse width modulated transistor outputs to be switched on or off. Bit 0 = Enable AB Bit 1 = A / Bit 2 = B Bit 3 = C / Bit 4 = D Bit 5 = Enable CD
- BYTE	EnableMask
Range 0-63 or 0b00000 to 0b111111
- VOID	Return

	Initialise
- VOID	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
	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.
	Connections
	Simulations