CN0420

The smart greenhouse application focuses on increasing the growth efficiency and maximizing the yield cycles of various types of plants. The theory and details apply to many agriculture sectors such as indoor greenhouses, vertical farming, and container farming. The smart greenhouse application addresses other general concerns for users in the agriculture market, such as keeping operating costs down and decreasing overhead (preventing over watering or wasted soil enrichment).

The smart greenhouse application hardware is made up of three different Circuits from the Lab reference designs.

The CN-0397 is designed to measure the intensity of the visible light spectrum, particularly at the wavelengths that correspond to the colors red, green, and blue (RGB). Red and blue light are absorbed by the plant and used during photosynthesis, whereas green light is reflected by the plant. Each sensor measures the intensity of light at its targeted wavelength and outputs a proportional current. The CN-0397 converts that small current into a voltage, and transforms the voltage into the standard unit of measurement for light intensity (Lux). See the CN-0397 for more information on how the circuit operates.

The CN-0410 is a programmable, 3-channel, current drive LED circuit. Each channel of RGB is independently controlled, allowing for unique LED color combinations. The board allows connection to the CFTL-LED-BAR by connecting the terminal block on each board together with a twisted pair wire. Light intensity commands are sent via Wi-Fi to the smart greenhouse, and a proportional integral (PI) software control loop between the CN-0410 and the CN-0397 is used to create the RGB color combination.

The CN-0410 also has an isolated repeater function on the board, so that the user can set multiple banks or bays of CN0410 and LED bar combinations to a single value with only a single controller board, which minimizes the cost over a large LED network. See the CN-0410 documentation (available from the circuit note webpage) for complete details on the repeater function, LED settings, and power consumption.

The CN-0398 measures three other critical parameters including soil moisture, pH, and temperature. Soil moisture measurements are important to ensure that the vegetation has the proper amount of water to promote growth, and also to ensure that water is not being unnecessarily wasted. pH monitoring is also important. pH affects nutrient availability and absorption of potentially harmful materials. Some plants germinate or flower within certain temperature requirements or profiles, and therefore the temperature measurements are used to help regulate the HVAC system. See the CN-0398 for more information on how the circuit operates.

The ADICUP3029 Arduino form factor-compatible development platform controls the Arduino shield hardware modules described previously. This platform contains the ADuCM3029 ultra low power Cortex-M3 microprocessor. The development platform also has onboard Bluetooth and Wi-Fi connectivity for connection to the internet and development of IoT connected applications.

For the smart greenhouse application, data is sent wirelessly from the node (ADICUP3029 and shield modules) to an existing wireless gateway through Wi-Fi. The Wi-Fi uses a message queuing telemetry transport (MQTT) standard protocol, which is typically used in low power, IoT sensor nodes that need to send small amounts of data to the gateway.

The IBM^® Watson cloud service is used to collect and display the smart greenhouse data. Bidirectional communication receives the data and transmits it from the cloud service back down to the remote node. There are other connectivity options available. For complete details on the IBM Watson option and other cloud connection options, see the Smart Greenhouse Wiki User Guide.