Development of Wireless Weather System

1. Abstract

 The weather monitoring system has a vital role in the environment and has various applications. Data gathering can be difficult if obtained manually. The Arduino based platform aims to provide a solution for an ease of monitoring weather conditions in a certain area. The system is design and implemented through an open-source software and printed circuit boards. The development of the project is based on real time monitoring of temperature and humidity variables through sensors and wireless communication devices. The parameters are gathered automatically without human intervention and can be triggered to provide immediate actions depending on the suitable weather conditions of the certain area.

2. Introduction

Weather is a state of atmospheric condition at a given time and location on the Earth. Most weather changes occur on the part of Earth’s atmosphere called the troposphere. Several factors that may affect atmospheric condition includes temperature, humidity, air pressure, wind speed, etc. (The Editors of Encyclopaedia Britannica, 2019) The weather changes can create a substantial impact on day-to-day lives of people around the world. Extreme weather phenomena can lead to people displacement, interruption of economic activities, damaged crops for food production, can impede transportation and increase the frequency of accidents.

Weather predictions and weather forecasting on variable changes of atmospheric conditions has been a long-standing human concern. The development of weather stations and scientific measurements of weather data has evolved since mid-19^th century. (Robbins, 2019) Different instruments are being studied and used to acquire precise and accurate weather data. Monitoring weather conditions plays a vital role in the environment to suite the working conditions in a specified area and necessary for planning purposes. Weather monitoring can also detect future changes to avoid adverse impact to the environment and human life. (S, 2004)

A weather station is a device that uses instruments to measure and collect data related to weather condition in a certain area. Monitoring the weather data manually can be difficult as it requires quantitative data of the atmospheric state using absolute scientific analysis. With the conventional weather monitoring system, it also lacks efficiency and effectiveness in predicting the weather phenomena. (Bennett, 2018)

Today, the modern technology of weather system involves several sensors and wireless communication devices that can be integrated into fast and accurate monitoring and controlling of data. Hence, the aim of this project is to build a weather monitoring system that is low maintenance and has the capability of wireless transmission and recording of data in a real time manner.

3. Background/Related Works

The development of weather stations has evolved over the centuries  and several significant weather events have affected the humankind over time. Adverse weather conditions has negative impact to the environment and affected many people. Including period of drought, hurricane impact, noticeable blizzards, smog events, life-threatening storms and flash floods. Scientist has worked to develop analogue instruments like anemometer, barometer, thermometer, rain gauge and wind vane. These types of instruments requires high maintenance and cause significant drawback in the understanding the atmospheric process. (Moore, 2015)

 In today’s modern age and technology, meteorologist studied several approach in weather monitoring system. The development of various sensors and wireless communication devices are viable. One of these is satellite based communications, that uses satellite imagery to capture a vast array and high quality of data from cloud temperature, wind speed, severe thunderstorms, and other tropical disturbances. Using this technology can be very helpful as it analyses long-range weather forecasts. However, using the weather satellites can be costly to launch and operate. On the other hand, the GSM based system utilizes a mobile phone for monitoring and recording of data. The system is low-cost and provides real time data. Yet, severe weather conditions may impede the transmission of weather parameters from remote location to the base station. (Jitendra Singh, 2017)

 This project will implement a wireless weather monitoring system using an Arduino microcontroller that is integrated with sensors to measure weather parameters. Monitoring of data is sent wirelessly to an indoor base station based on real time variables.

(Dejan, 2017) 

4. Proposed Project – Working Principle

The proposed project of wireless weather monitoring system shows the overall system operation and functionality. The Arduino Nano microcontroller serves as the main controller of the unit. The data flow from the temperature and humidity sensors including the real time clock are embedded to communicate to the microcontroller. The transmission of data between the indoor and outdoor unit is through the transceiver module. Monitoring and analysis of data can be viewed via the OLED screen.  The modules on the system are made sure that it can give accurate data and have no compatibility issues with the Arduino.

The system will consist of two circuits: 1) indoor unit -  consists of Arduino Nano, temperature and humidity sensor, real time clock module, transceiver module and OLED display. 2) outdoor unit – consists of Arduino Nano, transceiver module and temperature and humidity sensor. Both units have 9VDC battery for power supply.

4.1  Block Diagram                  

              Figure 1. Block Diagram of the Proposed System

4.2  Bill of Materials

Figure 2: Bill of Materials

5. Project Design

5.1 Components

         The design of the wireless weather monitoring system has the following components:

              a. )  Arduino Nano – The main controller of the unit that is an open source platform for any development environment. Arduino Nano has a compact design microcontroller based on ATMega328p developed by Arduino.cc. It has an operating voltage of 5V and a varying voltage of 7-12V. It based on AVR architecture and can be powered thru mini-USB connection. The ATmega328 has 32 KB of memory, with 2 KB used for the bootloader. The ATmega328 has 2 KB of SRAM and 1 KB of EEPROM. Arduino Nano has 14 digital pins that can be used for input and output. It has 8 analogue inputs that provides 10 bit of resolution.  The Arduino Nano can be programmed through an Arduino software and includes a Wire library for to simplify the use of I2C bus which is used for communicating in other external devices. The ATmega328 provide UART TTL serial communication to communicate with computer and other microcontrollers.

Figure 3: Arduino Nano Pinout Diagram

Figure 4: Arduino Nano Technical Specifications

b. ) DS3231 RTC Module – a low cost, extremely accurate module developed by Maxim used for timekeeping functions. It has an embedded battery that keeps the module running in case of power failure. It has an operating voltage of 5V and uses I2C interface for communication. DS3231 RTC module also comes with a 32 bytes 24C32 EEPROM chip from Atmel having unlimited read-write cycles. Another feature of DS3231 RTC module is the SQW pin, it outputs a square wave function that can be programmed and can be used as an interrupt to an alarm function for time-based application. It is also driven by 32kHz temperature compensated crystal oscillator (TXCO) that is highly immune to external temperature changes. IT provides a stable and accurate reference clock, and maintain within ±2 minutes per year accuracy. It uses RTClib.h library for communication to the module.

Figure 5. DS3231 Pinout Diagram

 c. ) DHT11 -  used as the temperature and humidity sensor. It has a dedicated NTC (Negative Temperature Coefficient) to measure temperature and an 8-bit microcontroller to output the values of temperature and humidity. The sensor can measure temperature from 0°C to 50°C and humidity from 20% to 90% with an accuracy of ±1°C and ±1%. In the system,  10k pull resistor was installed to interface with the Arduino microcontroller.

Figure 6. DHT11 Pinout Diagram and Technical Specifications

d. ) 0.96 OLED Screen – the readings from the sensors are display on the OLED screen. It is 0.96” made with 128×64 pixel, consumes less power and has high contrast that doesn’t need backlight. The operating voltage is 5V and uses I2C interface as communication protocol in Arduino Nano.

Figure 7. OLED Display Pinout and Technical Specifications

                 e. ) NRF24L01 – the transceiver module. The NRF24L01+ is a single chip 2.4GHz transceiver suitable for ultra-low power wireless communications. It operates on the world wide ISM frequency band and uses GFSK modulation for data transmission. The operating voltage is 1.3 to 3.6V and communicates over a 4-pin Serial Peripheral Interface (SPI) with maximum data rate of 10 Mbps.

Figure 8. NRF24L01+ Pinout Diagram and Technical Specifications

5.2 Circuit Diagram

The circuit diagram shows all the necessary connections to implement the wireless weather monitoring system.

         Figure 9: Schematic Diagram

5.3 Schematic Diagram

The PCB layout is designed with two layers for both indoor and outdoor units: Top and Bottom Layer

Figure 10. PCB Layout: Top Layer

Figure 11. PCB Layout: Bottom Layer

6. Project Implementation

The Arduino Nano microcontroller is the main component of the wireless weather monitoring system and is connected to sensors, real time clock and the wireless communication device.  The outdoor unit has DHT11 sensor that measures the temperature and humidity. The data is sent wirelessly to the indoor unit using the NRF24L01+ transceiver module. At the indoor unit, there is another Arduino Nano that is connected to DHT11 to measure the indoor temperature and humidity. A DS3231 RTC was also installed for timekeeping purposes as well as storing the real time data when the Arduino loses its power. The system consist of OLED screen wherein the data measured by the sensors are displayed for monitoring purposes. A fan was installed that serves as controlled output to regulate the room temperature, the setting is defined by the user depending on the weather circumstances.

The overall connection of the wireless weather monitoring system are based on Fig. 9, which resembles the schematic diagram of the both the indoor and outdoor unit. Both units are have an external power source  that is connected to 9V DC battery since the operating voltage of each of component uses 5V and GND from the Arduino Board. Both the OLED display and the DS3231 RTC uses I2C interface for communication with Arduino and is connected to A5 (SCL) and A4 (SDA) respectively. In accordance with DHT11 sensor, the data pin is connected to pin 8 on the Arduino Nano board. A 10k pull-up resistor is also placed between the VCC and data line to keep proper communication between the sensor and microcontroller. As for the NRF24L01+ transceiver module, it is connected to the hardware SPI pins on the microcontroller for better performance and communication. A capacitor was also placed to keep the power supply more stable.

The circuit diagram is implemented on the PCB (printed circuit board) to keep the components and connections organized. The PCB layout of the wireless weather monitoring is based on Fig. 10 and Fig.11, which is made through an EasyEDA circuit design software. Both the indoor and outdoor unit share the same PCB layout, however the Arduino Nano board are programmed independently.

The Arduino IDE is the software used to program the system. The outdoor and indoor unit are programmed differently. For the outdoor unit, it serves as a transmitter of the wireless communication to send data to the indoor unit using DHT library and RF24 library. To enable wireless communication, the variables are defined according to pinout connections of the modules to the Arduino Nano board. The data read by the DHT11 sensor is included on the loop section. In order for the data to be sent to the indoor unit, the functions on the RF24 library is used, then the variables are converted into single String variable, and included in the character array. The Arduino Nano is also set to consume less power. For the indoor unit, two additional libraries are included: DS3231 RTC library and U8G2 library for the OLED display. In the same instances, the variables are defined and establish pinout connections to the Arduino Nano Board. Bitmaps are also utilized to make icons for the temperature and humidity values. For proper communication between the transceiver module, OLED and real time clock module, it was initialize on the setup section of the code. In the loop section, incoming data from the NRF24L01 is constantly check and read. Another declared function on the U8G2 library displays the various data with intervals to be displayed on the screen. Using the functions of the U8G2 library, it prints the display of temperature and humidity from the outdoor and indoor unit along with date and time information. (Please see Appendix 12.2 for code explanation. )

7. Challenges in Implementation

Implementing the hardware and software of the wireless weather monitoring system can be a great challenge. It requires skills and knowledge in each of the hardware components to be interconnected to the main controller which is the Arduino Nano. Datasheets and technical specifications are carefully looked into for better understanding to avoid burnt boards and components, along with compatibility issues. Also, proper pinout connections and wiring on the components. During the implementation of the circuit diagram to PCB layout, all connections are carefully checked. However, some of the connections were short-circuited. Another considerations are to test and troubleshoot the PCB in order for the system to work. See Fig.12 for adding jumper wires in circuit as part of troubleshooting connections. Also, implementing the Arduino IDE software can be a bit challenging as it requires an in-depth understanding of the programming language. Though the Arduino platform is an open-source, it is complex and needs the basics for instructions, defining variables and the correct libraries for proper communication between the microcontroller and the device.

Another challenge is purchasing the materials for the system, some of the components are outsource online as it was not available in some electronics stores here in NZ.

Figure 12: PCB revision

8. Limitations of the project

The wireless weather monitoring has the following constraints:

a)      The system is developed for a short distance from the outdoor unit to indoor unit to communication properly. The distance limitation is up to 1000meters within line of sight and without obstruction.

b)      The data is printed on the display and not stored on a database since the memory of Arduino Nano allows only certain amount of codes to be written.

c)       The power supply uses 9V battery, and might be discharge for a few days. However, the batteries are rechargeable.

9. Conclusion

The wireless weather monitoring system demonstrates the weather parameter in an area that can determine the temperature and humidity read by the sensors. The outdoor unit can be placed in a remote location in which the monitoring of the data can be display on the base station which is the indoor unit. The gathered information for the weather monitoring can be beneficial to different sectors such as outdoor gardening, maintaining a controlled room environment which can help manage the plan and works based on weather situations.

The system can be furthered modified such as integrating into IoT platform for remote monitoring that can be viewed thru and app or web-based system. Also, adding more sensors for data accuracy along with storage database an increasing the distance of wireless communication device. A solar panel can also be implemented for power efficiency.

10. References

• Bennett, B. (2018, 22 March). What’s the point of a smart weather station? Retrieved from CNet: https://www.cnet.com/news/what-is-the-point-of-a-smart-weather-station/
• Components 101. (2018, March). Arduino Nano. Retrieved from Components 101: https://components101.com/microcontrollers/arduino-nano
• Dejan. (2017, May 27). Arduino Wireless Weather Station Project. Retrieved from How to Mechatronics: https://howtomechatronics.com/tutorials/arduino/arduino-wireless-weather-station-project/
• Jitendra Singh, R. M. (2017). Arduino Based Weather Monitoring System. International Journal of Advanced in Management, Technology and Engineering Sciences, 1076 – 1079. Retrieved from Academia: https://acadpubl.eu/jsi/2018-118-16-17/articles/16/31.pdf
• Last Minute Engineers. (2019). How DHT11 DHT22 Sensors Work & Interface With Arduino. Retrieved from Last Minute Engineers: https://lastminuteengineers.com/dht11-dht22-arduino-tutorial/
• Last Minute Engineers. (2019). How nRF24L01+ Wireless Module Works & Interface with Arduino. Retrieved from Last Minute Engineers: https://lastminuteengineers.com/nrf24l01-arduino-wireless-communication/
• Last Minute Engineers. (2019). Interface DS3231 Precision RTC Module with Arduino. Retrieved from Last Minute Engineers: https://lastminuteengineers.com/ds3231-rtc-arduino-tutorial/
• Last Minute Engineers. (2019). Interface OLED Graphic Display Module with Arduino. Retrieved from Last Minute Engineers: https://lastminuteengineers.com/oled-display-arduino-tutorial/
• Moore, P. (2015, April 30). The birth of the weather forecast. Retrieved from BBC News Magazine: https://www.bbc.com/news/magazine-32483678
• Robbins, C. (2019, April 7). A Brief History of Weather Forecasting. Retrieved from iWeather: https://www.iweathernet.com/educational/history-weather-forecasting
• S, A. (2004, June 27). The Importance of Weather Monitoring. Retrieved from Pollution E quipment News: https://www.pollutionequipmentnews.com/the-importance-of-weather-monitoring
• The Editors of Encyclopaedia Britannica. (2019). Weather. Encyclopædia Britannica, Inc. Corporate Site.

12. Appendix

12.1 Arduino IDE Software Code

 a) Indoor Unit

b) Outdoor Unit

12.2 Code Explanation

12.3 Initial testing of the components on Breadboard

12.4 Final Prototype of PCB Layout

12.3.1 Top Layer           

12.3.2 Bottom Layer

12.5 Soldering components

12.6 Final Prototype