A basic environmental monitoring system for a reptile terrarium based on the Arduino enviromnent. Features LCD display integration for simplified readings.
Abstract This project documents the inception, assembly and programming performed in pursuit of a custom lizard tank environmental monitoring system. After identifying key variables critical to proper bearded dragon health; temperature, light and humidity, hardware was procured to address the challenge. An Arduino UNO microcontroller board was chosen to support three different sensors, allowing data collection of the aforementioned environmental variables. Additionally, an LCD screen was employed to facilitate rapid understanding of current tank condition data to the caretaker, and the entire system packaged for ease of deployment.
Background Bearded dragons, like all reptiles, are ectotherms. Unlike mammals, reptiles are unable to actively regulate their body temperature. As such, reptiles rely on their location in the environment to maintain a healthy body temperature; often shifting between shaded and sunlit areas. Owning a bearded dragon requires careful consideration into a living environment, or terrarium (Fig. 2). Terrariums are large glass tanks outfitted to replicate a natural living environment, including heat and UV-B lamps to produce light and warmth
Environment While the prospect of maintaining a bearded dragon terrarium may seem daunting, the task can be reasonably simplified into three critical variables. First and foremost, the terrarium temperature is the most critical condition to monitor as it is the limiting factor when compared to other needs. Closely related to temperature is light, of which a bearded dragon requires a near-constant supply throughout the day. Finally, humidity must be carefully regulated, as the environments where bearded dragons naturally exist are comparatively arid to a common home. While there exists a plethora of reputable sources providing information on the proper environmental conditions for bearded dragons, the suggestions found in the majority of these are harmonious.
Design requirements The system:
- Shall not harm or injure the bearded dragon.
- Shall not interfere with any existing implements within the tank.
- Shall display a reading of internal temperature taken within the terrarium.
- Shall display a reading of internal humidity taken within the terrarium.
- Shall indicate current light level in a simple, unitless fashion.
- Shall be packaged such that only sensors and power cables are exposed.
Design Description The monitoring system (Fig. 4) is comprised of an Arduino UNO microcontroller, power supply, temperature sensor, humidity sensor, light sensor, LCD screen, extension leads, breadboard and mounting enclosure.
The sensor package consists of three environmental sensors external to the enclosure and designed for placement within the terrarium. A DS18B20 Temperature sensor is powered via 5 volts and provides an accuracy of ±0.5°C from -10°C to +85°C, outputting a 12-bit temperature to a digital word value via the 1-Wire Arduino library. Next, a SHTC3 humidity sensor supplied with 3.3 volts offers a relative humidity (RH) reading of ±2%. Finally, a SEN-09088 Mini Photocell is powered with 5 volts and offers a varying level of resistance depending on lighting conditions, with higher readings corresponding to lower ambient light levels. This relationship required manual calibration in order to match known light levels to resistances.
Construction Photos
