The first working test version of the real-time connection for a sensor with in situ application is in progress. This sensor runs sanitized wiring through the air lock which then goes through a waterproof housing into the liquid.
The sensor is connected over wifi which then transmits updates over an IoT backbone. Currently, it is logging temperature changes into a Google Spreadsheet.
The graph shows an example log from 26 hours. Not that the temperature fluctuated within a 2 degree Celsius range over this period.
Next steps include adding additional ambient temperature sensors and also to develop the in situ hydrometer sensor.
The central gateway for the network is the base station. Now working is a color LCD touch display for the base station, with a WiFi module, and a local radio communications module which connects to the sensor and control networks on the ultra low power wireless network.
In the above figure, at the bottom is the microcontroller (MCU) based on the ESP 8266 system on a chip, which includes 802.11 b/g/n WiFi standards. The display will show the user interface which is under development and is a touch screen, which enables the user to configure and set options. To the top right the low power wireless radio is shown, which is used to interface to the local sensor network, and control network.
At this point, the hardware for the base station is basically complete, and the primary work at this point is in further developing the software both on the embedded MCU, for the web-based service, and for the mobile applications.
The new temperature and humidity modules have arrived!
These modules have an on-board 8-bit processor to ensure the readings are calibrated. They have low power consumption making them ideal for the sensor node application. They consume 0.3 mA when taking a measurement, but only 60 pico Amps in standby!
Another step closer to putting the sensor node together. All of the basic parts are now ready, except for the power supply. Progress is being made on that as well.
The initial prototyping will involve a two-pronged probe to be inserted into the ground.
This probe works by measuring the resistance of a small current through the soil. The greater the moisture content, the more conductive the soil will become. This probe will be placed at the bottom of the solar powered sensor node, which will look like a garden solar light.
Of course, this sensor does not have to be always on, and so it will be important for the wireless node to be able to turn off the sensor between readings in order to conserve power. The total current draw of this sensor will have to be verified to manage the duty cycle.
Monitor temperature and humidity in various places within your greenhouse.
Options to include ability to connect to automation for air-circulation, heaters, ventilators.
For heated greenhouses, a single source of heat may not be dispersing throughout the interior, especially when the out-door temperature is low, the heating may not be applied ideally for plants near the edge of the greenhouse. By installing an automated monitoring system, the entire greenhouse can be configured to optimally distribute heat to all plants by turning heaters and fans on and off as required.
Is your lawn or garden on a timer? Do you manually water? Do you research the weather to see how much it is going to rain before watering? Finally, do you know the right amount of water to give each plant in your garden to make it thrive?
All of these questions can be easily resolved by the technology being developed to integrate and automate gardening. How it works:
- Base Station: A networked base station in the house connects to your home WiFi network and also the low power garden network.
- Distributed Sensors: Sensor modules which run on batteries and are charged by solar power are placed throughout the garden in strategic locations to collect information on ground moisture, temperature, humidity, and other information in real-time.
- Watering: You install a watering system to disperse water appropriately. There are many options for how to do this, with varying expense.
- Valves: Install wireless controlled water gates which can controlled manually from any internet enabled device, or, can be connected to a base station for automatic (smart) operation.
- Learning: By monitoring the level of moisture achieved by various amounts of water, the system learns your drainage and soil type to optimize when to water, and how much.
- Tuning/Zones: Not every plant requires the same amount of water. Configure your base station with information on what plants are near each sensor, and the base station will use this information to control the amount of water delivered.
The prototype of a sensor node is shown below. The screen is only to show the status of the system. Visible directly above the screen is the ultra low-power wireless module. The zig-zag wire is the antenna. To the left of the antenna, you can see the CPU.
Development of a product which is inexpensive, low-power, and wireless is now possible.
Now under development is a capability to deploy wireless solar-powered nodes which communicate with one another, controlled by a base-station. The nodes can send messages containing their sensor readings which are then processed, logged, and displayed by the base-station.. These nodes can run years on a battery, and re-charge their batteries using solar power. The most exciting part is that they can be built relatively cheaply. The goal is to get to a point where they are on the order of $20 each.
By having numerous inexpensive nodes, it also makes it easier to customize the total network to contain the capabilities requested or required for the task at hand. Since the wireless node communications are all inter-operable, adding an additional sensor will be very easy.