The aim of this project is to make a simple and reliable solar power harvesting circuit and then using the circuit to power a weather station which will remotely monitor basic weather parameters like temperature, pressure, humidity, wind speed /directions and rain fall etc.
The Power harvesting circuit is made of TP4056 IC . The circuit can be used for any single Li Ion battery powered applications.
The Weather Station has the following features:
1. The Weather Station can measure Temperature, Humidity, Barometric Pressure, Altitude
2. You can monitor the above weather parameters from your Smartphone or from the web.
3. The whole circuit along with power supply is put inside a 3D printed enclosure.
4. The range of the WiFi is around 100mt with an external antenna.
You can now see my new version of weather station.
After installing the above libraries, paste the Arduino code given in files section of this project.
Enter the auth code from step-1, ssid and password of your router.
Then upload the code.
To upload the code, following settings are preferable :
PU Frequency: 80MHz 160MHz
Flash Size: 4M (3M SPIFFS) – 3M File system size 4M (1M SPIFFS) – 1M File system size
Upload Speed: 921600 bps
Implementing Power Saving Mode :
The ESP8266 is a pretty power hungry device. If you want your project to run off a battery for more than a few hours, you have two options:
1. Get a huge battery
2.Cleverly put the Thing to sleep.
The best choice is the second option.Before using the deepsleep feature, Wemos D0 pin must be connected to the Reset pin.
Credit : This was suggested by one of the Instructables user " tim Rowledge ".
More Power Saving Option :
The Wemos D1 Mini has a small LED that lights when the board is powered. It consume lot of power. So, just pull that LED off the board with a pair of pliers. It will drastically drop the sleep current down .
Now the device can run for long time with a single Li Ion battery.
The Wemos D1 mini Pro board have a inbuilt ceramic antenna along with provision for connecting an external antenna to improve the range.Before using the external antenna, you have to reroute the antenna signal from the built-in ceramic antenna, to the external socket.This can be done by rotating the small surface mount (0603) Zero Ohm resistor (sometimes called a link).
You can watch this video made by Alex Eamesto rotate the zero ohm resistor.
Then snap the antenna SMA connector in to the Wemos Pro mini antenna slot.
In the earlier days weather parameters like ambient temperature,humidity and barometric pressure were measured with separate analog instruments: thermometer, hygrometer and barometer.But today the market is flooded with cheap and efficient digital sensors that can be used to measure a variety of environmental parameters.The best examples are sensors like DHT11, DHT 22, BMP180, BMP280 etc.
In this project we will use a BMP 280 sensor.
BMP 280 :
BMP280 is a sophisticated sensor that very accurately measures barometric pressure and temperature with reasonable accuracy. The BME280 is the next-generation of sensors from Bosch, and is the upgrade to the BMP085/BMP180/BMP183 - with a low altitude noise of 0.25m and the same fast conversion time.
The advantage of this sensor is that it can use either I2C or SPI for communication with microcontroller. For simple easy wiring, I will suggest to by I2C version board.
The Power harvesting circuit is made of TP4056 charging IC and DW01 li Ion battery protection IC.
About the TP4056 :
The TP4056 IC is a complete constant current/constant-voltage linear charger for single cell lithium-ion/Lithium Polymer (LiIon/LiPo) batteries. Its SOP-8 package and low external component count make the TP4056 ideally suited for portable applications.
Other features include :
1. Current monitoring
2. Under voltage lockout
3. Automatic recharge
4. Two status LED to indicate full charge and the presence of an input voltage.
To know more about TP4056, you can read the Data Sheet.
About the DW01 :
The DW01 battery protection IC is designed to protect lithium-ion/polymer battery from damage or degrading the lifetime due to overcharge, overdischarge, and/or overcurrent for one-cell lithium-ion/polymer battery powered systems.
To know more about DW01 , you can read the Data Sheet
I used a ready made module which include both TP4056 and DW01 ICs. This module will offer 1000 mA charge current then cut off when charging is finished. Furthermore when the battery voltage drops below 2.4V the protection IC will cut off the load to protect the cell from under voltage. It also protects against over voltage and reverse polarity connection.
Wemos modules come with variety of headers but you have to solder it according your requirement.
For this project,
1. Solder the two male headers to the Wemos D1 pro mini board.
2. Solder a 4 pin male header to the BMP 280 module.
After soldering the headers the module will look as shown in the above picture.
Adding Headers and Terminals
Next step is soldering the headers to the perforated board.
1. First place the Wemos board over the perforated board and mark the foot print.Then solder the two row of female headers over the marked position.
2. Then solder a 4 pin female headers as shown in the picture.
3. Solder a screw terminals for battery connection.
Mount the Charging Board :
Stick a small piece of double sided tap on the back side of the charging module and then paste it on the perforated board as shown in the picture.During mounting care should be taken to align the board in such a way that the soldering holes will match with the perforated board holes.
Adding terminal for Solar Panel
Solder a screw terminal just near the micro USB port of the charging board.
You can solder this terminal in the earlier step also.