sensor-dht11 — WildlifeSystems

Overview

The DHT11 is a widely available, low-cost sensor that measures temperature and relative humidity. In biodiversity monitoring, these two variables are among the most important drivers of species activity — influencing when insects emerge, when amphibians vocalise, and how quickly vegetation responds to seasonal change.

sensor-dht11 is a lightweight C implementation that reads DHT11 sensors via GPIO on the Raspberry Pi. It uses real-time scheduling (SCHED_FIFO) for reliable bit-banging and outputs JSON compatible with the WildlifeSystems sensor-control framework.

Measurements

Temperature — degrees Celsius
Humidity — relative humidity percentage

Installation

Via the WildlifeSystems APT repository:

sudo apt update
sudo apt install sensor-dht11

Or build from source:

make
sudo make install

Usage

sensor-dht11                    # read all sensors
sensor-dht11 temperature        # temperature only
sensor-dht11 humidity           # humidity only
sensor-dht11 internal           # internal sensors only
sensor-dht11 external           # external sensors only

Configuration

Configure sensors in /etc/ws/sensors/dht11.json:

[
  {
    "pin": 4,
    "internal": false
  }
]

pin — GPIO pin number (2–27)
internal — whether the sensor is inside the enclosure
sensor_id — optional custom identifier

Example Output

[
  {"sensor":"dht11_temperature","measures":"temperature","unit":"Celsius","value":23.0,"internal":false},
  {"sensor":"dht11_humidity","measures":"humidity","unit":"percentage","value":45.0,"internal":false}
]

Source Code

sensor-dht11 on GitHub →