Evapotranspiration Calculation System

Evaportranspiration is the sum of two processes: soil evaporation and plant transpiration, in which evaporation is the process of passing from the liquid state to the vapor state. For example, surface water (such as rivers and lakes) is heated by solar radiation and evaporates, and transpiration occurs when the water that plants absorb from the soil is eliminated by the leaves in the form of water vapor, through the stomata.

Evapotranspiration is all the movement of water in liquid form returning to the atmosphere, which makes it a factor that is directly linked to the presence of water in the Plantation, and that helps to carry out irrigation in a more sustainable and economical way. Because it is through evapotranspiration that the water requirement for crops is estimated, and through this knowledge it is possible to define irrigation with greater precision.

And knowing the water demand of crops is important to be able to exploit the maximum production potential. This is because the lack of water during development, in most crops, results in productivity drops and its exaggeration brings waste.

This project consists of a piece of equipment accessible to small farmers capable of reading environmental conditions throughout the day and informing the following day of evapotranspiration so that adequate irrigation can be dimensioned.

The systems consist of a central that works in three ways:

• The first case is completely offline in case the location does not have access to mobile or wireless networks. In which, when the farmer wants to know the information, he visualizes it on the display of the equipment itself and in the case of wanting more information or of several days on the wireless network of the equipment, he visualizes the data in more detail and can export this data to a spreadsheet.
• The second case is the equipment being close to a wireless network. In which it is connected to this network and reports data also through this network and allowing data to be stored in an online database that the farmer can see anywhere that has internet
• The third Case is when the area where the equipment will be installed does not have wireless but has mobile data where the farmer needs to monitor the data outside the property where the equipment will be configured to use mobile data.

Prototype

The prototype was initially developed for situations one and two where you only have access by viewing the display or connecting to a 2.4ghz wireless network, in which the next step is to test on the developed board that I am still waiting for to arrive and test the third situation.

Power Board:

The Power board receives the voltage from the solar board and converts it to a suitable voltage for charging the batteries and running the labrador32

BaseBoard Caninos:

The caninos baseboard is responsible for connections, wireless and power

Labrador32:

This core board was chosen because this project is Brazilian and the only mini-computer I had access to at the beginning of the project, but because it is a national project, the development community is small, making it difficult for me to work around some points with esp.

Specifications:

CPU: 32-bit quad-core ARM® Cortex™ 1.3GHz

A9R4 CPU (ARM v7 instruction set)

GPU: Imagination PowerVR SGX544 *

Supports: OpenGL-ES 1.1 and 2.0, OpenGL 1.2.1, OpenCL 1.1*

Memory: 2GB DDR3 SDRAM

Storage: 32 GB eMMC

Operating System: Debian 10 Linux Kernel 32-bit

PMU: ATC2306C – Power Management and Audio Subsystem

Video : 1080p@60fps with video encoding support (including H264, H263, MPEG-4)

Expansion interface: 204-pin DDR3 SODIMM connector (male)

Dimensions: 67.6 x 42.2 mm

Weight: 13.6g

Sensor Board:

The sensor board is responsible for feeding the esp, communication with the display and anemometer. At first it was with bme280 but an rj45 connector was inserted for it to be connected externally.

Anemometer:

Anemometer was printed in ABS and its internal electronics consists of Hall sensor smd together with magnet connected to an rj45 port.

Designed Plate

To replace the three scoreboards of the prototype, everything in one board was designed with the components below:

Functions:

• Power:

• Camera Connection for plantation monitoring (For Future Use) and 2x USB 2.0 ports (for future functions as usb camera)

• Connection for 3.7V battery for when the sun is weak working during the night

• Module Lora Ra-02 for communication with other modules at a distance that wireless 2.4ghz and 5ghz does not allow and SIM800C module for GSM/GPRS connections

• Mobile Chip, Connections for Anemometer and BME280, USB Type C for connecting peripherals such as hubs in case of maintenance on site which equipment is installed, System Power and Reset Buttons and Connection for solar panel or sources up to 22V

• Wireless Network Card Ap6255 is responsible for 2.4ghz and 5ghz connections.

• Esp8266 responsible for taking the anemometer and BME280 readings and sending the data to be stored local bank in the labrador32

Display conector and led Charging

Level Shift to Display

Getting off the board:

• Bme280 for reading humidity, temperature and pressure.
• Anemometer
• Lithium 3.7 batteries
• Solar plate
• Display 20x4

Case

The case was designed to only show the display and in case of rain, water does not enter the system.

It has a support in the case to be attached to a cylindrical rod, having access to connections only from below when the bottom cover is removed. Also having an internal support to hold the plate, display and place for the battery bank in which this support to be removed from inside the case needs to be unscrewed two screws at the back of the case to pull the support down having access to the entire system