B4J Library [Raspberry Pi] jDHT - Digital-output relative humidity & temperature sensors

Library for the DHT11 & DHT22 digital-output relative humidity & temperature sensors connected to a Raspberry Pi.
The library
  • is based upon this project (recommend to read the blog).
  • if a sensor value can not be read, NaN is returned.
  • tested with the sensors DHT11 and DHT22 (see sample code) connected to a Raspberry Pi 3.
upload_2017-3-6_10-39-23.png


Install
Copy jdht.jar, jdht.xml and dht.jar to the B4J additional libraries folder. Copy libdht.so to the dirapp folder.
When testing on the Raspberry Pi using the B4J-Bridge, ensure libdht.so is in the tempjars folder.

Wiring
B4X:
DHT11 = Raspberry Pi 3
5v = 5v
Data = Physical Pin #16 [BCM23]
GND = GND

DHT22 = Raspberry Pi 3
5v = 5v
Data = Physical Pin #15 [BCM22]
GND = GND

Example B4J Non-UI Program
B4X:
Sub Process_Globals          
  Private dht11 As DHT
  Private dht22 As DHT
  Private timer1 As Timer
End Sub

Sub AppStart (Args() As String)
  Log("AppStart")
  ' Init the sensor with sensortype and pin (BCM)
  dht11.Initialize(11, 23)
  dht22.Initialize(22, 22)
  timer1.Initialize("timer1", 2000)
  timer1.Enabled = True
  StartMessageLoop
End Sub

Sub timer1_tick
  Log($"DHT11 ${DateTime.Time(DateTime.Now)}: ${dht11.Temperature}*, ${dht11.Humidity}%"$)
  Log($"DHT22 ${DateTime.Time(DateTime.Now)}: ${dht22.Temperature}*, ${dht22.Humidity}%"$)
End Sub

Output
dht11 09:51:01: 19.9*, 41.7%
dht22 09:51:01: 19.9*, 41.7%
dht11 09:51:03: 18.0*, 44.6%
dht22 09:51:03: 18.0*, 44.6%
dht11 09:51:11: 18.0*, 56.4%
dht22 09:51:12: 18.0*, 56.4%
dht11 09:51:23: 18.7*, 71.7%
dht22 09:51:23: 18.7*, 71.7%

ChangeLog
20170306 v1.0
 

Attachments

  • jDHT.zip
    45.4 KB · Views: 517
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