Educational weather station - Page 1
Forum section: electronics / projects

author: Picuino
author_rank: Super Contributor
timestamp: April 18, 2025, 07:33:48 pm
content: I am working on a new project, an educational weather station.For now I am going to measure a few variables, simple to implement, such as temperature, humidity and atmospheric pressure. But later I do not rule out the possibility of measuring wind speed and rainfall.The basic specifications/components are:1.Arduino nano as controller. It is cheap, simple, has a wide base of components and libraries, is intended foreducationalenvironment.2.SHT31 sensorto measure humidity and temperature. More accurate than DHT11 or DHT22 sensors.3.BMP280 sensorto measure air pressure.4.Micro SD card readerto write the readings taken every hour.5.RTC DS3231(real time clock) to know the exact time of the sensor readings.6.NEO-6M GPSto know the location of the readings and to set the RTC from time to time.7.HC-05 Bluetoothmodule to connect the weather station with a PC and transmit all the readings8.Lipo battery(400mAh) for overnight operation.9.Photovoltaic solar panelto electrically supply the components (6V, 100mA).10. A lipobattery chargerand 5V boost power supply.Operation:The idea is to take temperature + relative humidity + atmospheric pressure readings every hour and write the readings to an SD card.The rest of the time all peripherals/sensors should be off (no power) and the Arduino in IDLE mode.From time to time, a computer will download all the readings taken thanks to the Bluetooth connection.Students can make graphs, averages and comparisons of readings taken in Math class and in Geography class. I'm not clear on what to ask them to do in Technology class, because the assembly and programming are quite complex. I will have to make programming that facilitates adding changes easily and an assembly schematic that they can do themselves.Low Power consumption:To achieve minimum power consumption, I disconnected the 5V voltage regulator pins of the Arduino Nano (at PCB) and also disconnected the power indicator LED. With these two changes and with theLowPower library, the Arduino only consumes 0.3mA.The sensors are disconnected/connected from the Arduino with a P-Mosfet between the 5V rail and the power supply of the modules.Ideas for improving the weather station:Does anyone have any ideas on how I can improve the weather station now that I am still in the design phase?

author: TimFox
author_rank: Super Contributor
timestamp: April 18, 2025, 07:43:52 pm
content: For outdoors measurements, be sure to shield the temperature sensor from sunlight, while keeping airflow to the sensor.

author: RoGeorge
author_rank: Super Contributor
timestamp: April 18, 2025, 08:09:20 pm
content: Maybe a LoRaWAN link instead of SDcard+Bluetooth.Other possible sensors:- Light intensity logging to know how cloudy is the sky- Piezo sensor for counting rain droplets- An E-field mill- Lightnings detector- Wind speed/direction

author: Picuino
author_rank: Super Contributor
timestamp: April 19, 2025, 04:37:58 pm
content: Quote from: TimFox on April 18, 2025, 07:43:52 pmI had thought of making a small roof to place the solar panel on top and the sensors underneath, but it had not occurred to me to install a small fan to improve accuracy.Quote from: RoGeorge on April 18, 2025, 08:09:20 pmThe light intensity is a good idea, and simple to implement (SI1145):https://store.arduino.cc/en-es/products/grove-sunlight-sensorThe rest will have to wait to find a suitable sensor. On the other hand I don't want to overcomplicate the final design either, so it won't be too difficult. One of the most difficult challenges is to bring this setup closer to teenagers so that they actively participate in the design/assembly/operation.

author: Picuino
author_rank: Super Contributor
timestamp: April 19, 2025, 04:41:04 pm
content: Quote from: RoGeorge on April 18, 2025, 08:09:20 pmI am not familiar with LoRa. I knew it existed, but I don't know how to connect it to the PC.Writing to SD is irreplaceable, in case we go a long time without reading the readings taken by the Arduino, to avoid losing them.

author: Picuino
author_rank: Super Contributor
timestamp: April 23, 2025, 11:23:35 am
content: The issue of supply voltages is giving me some problems. I have started with the HC-05 Bluetooth module, which apparently in some cases has 5V tolerant inputs, but in other cases does not.I didn't want to complicate the circuit more (with 10 modules interconnected it is already quite complex), but I think in this case I will have no choice but to add two resistors (1.8k and 3.3k) to reduce the output of the Arduino to 3.3V to the RX input of the module.It would be much easier to always work at 3.3V, but the arduino world is set up for 5V (more demanding on the battery) so I will have to feed everything with 5V and adapt some signals to 3.3V.

author: Picuino
author_rank: Super Contributor
timestamp: April 24, 2025, 05:07:47 pm
content: Provisional schematic.

author: Picuino
author_rank: Super Contributor
timestamp: April 25, 2025, 03:45:11 pm
content: I just realized that the modules connected by I2C (called TWI connection in Arduino) are modules with very low current consumption and it would be nice to be able to connect them independently of each other. That's why I'm going to power them from an output pin of the Arduino. That way I can better control which modules are working at each moment and, therefore, the total current consumption.Considering that this equipment must be autonomous and powered by solar panels and battery, the more electricity consumption can be saved, the better.

author: Picuino
author_rank: Super Contributor
timestamp: April 26, 2025, 05:54:00 pm
content: New schematic.

author: zapta
author_rank: Super Contributor
timestamp: May 07, 2025, 04:03:21 am
content: When you say "educational", what discipline you have in mind? Designing hardware or writing firmware? Climate studies? Data analysis? Math? Something else?

author: Picuino
author_rank: Super Contributor
timestamp: May 07, 2025, 06:52:59 am
content: The project is aimed at secondary school students (14 to 16 years old) and is intended to be multidisciplinary. The technical project will be developed in theTechnologydepartment, but the data generated will be used inMathematicsandGeography and History. For example, the historical context of the systematized data collection will be taught in Geography and History.Mathematics will use the data to make averages, trends and graphs.In the Technology part, we will study the electrical parts and I intend to have the students program variations to a base program that I will program with the idea that it will be easy to modify.

author: Picuino
author_rank: Super Contributor
timestamp: May 07, 2025, 07:00:58 am
content: Right now I am studying several communication modules to decide which one can be better (low power consumption and easy to operate).For now I have three candidates:* Bluetooth module HC-05* NRF24L01 module* LoRa SX1278 moduleThe Bluetooth module seemed easy to operate, but it consumes quite a lot of power when idle and I think it will not be easy to connect to it considering that most of the time it will have to be turned off.