Solar Powered WiFi Weather Station V2.0




This Instructable is a continuation of my earlier weather station project. It was quite popular on the web, people around the globe made their own by following it and given valuable feedback for improvement. By taking consideration of the comments and Q&A section of my earlier project, I decided to make this new version Weather Station. I also made a custom PCB for this project, so anyone with little knowledge on electronics circuit can be made this project. My V-2.0 PCB can also be used for any application in the Arduino platform. Following are the salient features of the new weather station.

This project is also an entry in Hackaday Prize 2019. Please like, follow and share. It will be helpful to me.


1. Connect to Wi-Fi, and upload the data to the web ( Blynk App and Thingspeak)

2. Monitoring Weather parameters like Temperature, Pressure, Humidity, altitude and UV level, etc.

3. Extra ports to add more sensors

4. Remote Battery Status Monitoring

5. Uses a powerful Li-Ion Battery ( 3400 mAh ) and Solar Panel (1W)

6. Independence from the external power source

7.Can be installed in remote sites or geographically challenging environments

8. Being Solar powered, it is an environment-friendly device.

Step 1: Components and Tools Required

Components Used :

1. Wemos D1 Mini Pro (Banggood / Amazon )

2. TP 4056 Charging Board (Banggood / Amazon )

3. BME 280 sensor ( Amazon / Bangood )

4. BMP280 ( Banggood / Amazon )

5. DS18B20 Sensor ( Banggood / Amazon )

6. Switch ( Banggood / Amazon)

7. Screw Terminals ( Banggood)

8. PCB standoffs ( Banggood / Amazon )

9. 18650 Battery ( Aliexpress)

10.18650 Battery Holder ( Banggood / Amazon)

11. Solar Panel ( Banggood )

12. Straight Headers Pin ( Banggood / Amazon )

13. 22 AWG wire ( Banggood / Amazon )

14. Weather Station V2.0 PCB ( PCBWay )

15. Super Glue ( Amazon )

16. 3D printing filament -PLA ( GearBest )

Tools Used :

1. 3D Printer ( Creality CR-10 )

2. Soldering Iron ( Amazon )

3. Glue Gun ( Amazon )

4. Wire Stripper ( Amazon )

5. Wire Cutter ( Amazon )

Step 2: Power Supply

My plan is to deploy the Weather station at a remote place ( my farmhouse).To run the Weather Station continuously, there must be a continuous power supply otherwise the system will not work. The best way to provide continuous power to the circuit is by using a battery. But after some days the battery juice will run out, and it is a really difficult job to go there and charge it. So a solar charging circuit was proposed to user free energy from the sun to charge the batteries and to power the Wemos board. I have used a 18650 Li-Ion battery.

The battery is charged from a Solar panel through a TP4056 charging module. The TP4056 module comes with battery protection chip or without the protection chip. I will recommend buying a module which has a battery protection chip included.

About the TP4056 Battery Charger

The TP4056 module is perfect for charging single cell 3.7V 1 Ah or higher LiPo cells. Based around the TP4056 charger IC and DW01 battery protection IC 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 overvoltage and reverse polarity connection.

Step 3: Monitoring Temperature and Humidity by BMP/E280

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, BMP/E280, etc.

In this project, we will use BMP280 / BME280 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 the microcontroller. For simple easy wiring, I will suggest buying the I2C version board.

BME280 :

The new BME280 sensor, an environmental sensor with temperature, barometric pressure, and humidity. The BME280 is the next-generation of sensors from Bosch and is the upgrade to the BMP280. This precision sensor from Bosch is the best low-cost sensing solution for measuring humidity with ±3% accuracy, barometric pressure with ±1 hPa absolute accuracy, and temperature with ±1.0°C accuracy. It can be used in both I2C and SPI.

Note: BME280 can measure humidity but BMP280 can't. In the market, BMP280 is also available by the name of BME280. So be sure whether it is a BMP280 or BME280.

Step 4: Additional Ports for More Sensors

The Weather Station V2.0 board have 5 additional ports to hook up more weather sensors. The following additional sensors can easily be hooked up :

1. GY-1145 Sensor: for measuring UV Index

The SI1145 is a sensor with a calibrated UV sensing element that can calculate the UV Index. It can communicate via I2C communication (address 0x60). You can hook up this sensor with I2C port in the board which is located just side to the power switch.

You can read this article to know more about this sensor.

You can buy this sensor from Banggood.

2. HDC1080: for measuring temperature and humidity

The HDC1080 is a digital humidity sensor with an integrated temperature sensor that provides excellent measurement accuracy at very low power. It can also communicate via I2C communication.

You can read this article to know more about this sensor.

You can buy this sensor from Banggood.

3. DS18B20: for measuring temperature

It can measure temperature with a minimal amount of hardware and wiring. These sensors use a digital protocol to send accurate temperature readings directly to your development board without the need of an analog to digital converter or other extra hardware. It uses a one-wire protocol to communicate with the microcontroller. It can be hooked up in port-P2 in the board which is located on the right side of the Wemos board.

You can read this article to know more about this sensor.

Step 5: Using an External Antenna ( 3dBi )

The Wemos D1 mini Pro board have an 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 see the above picture, how I have done this.

You can also watch this video made by Alex Eamesto to rotate the zero ohm resistor. Then snap the antenna SMA connector into the Wemos Pro mini antenna slot.

Step 6: Monitoring Battery Voltage

The weather station is run by a 18650 Li-Ion battery, so it is very important to monitor its status. The max voltage input to the Wemos board is around 3.2~3.3V but a fully charged 18650 battery voltage is 4.2V. So to measure this voltage we have to step down the voltage by using a voltage divider network.

The Wemos D1 mini already has an internal voltage divider that connects the A0 pin to the ADC of the ESP8266 chip. The voltage divider is made up of 220k (R1) and 100k (R2). So, we have to add an external resistance with the inbuilt 220k resistor to read the battery voltage. By using a 100k resistance we can measure the max voltage of the battery, but taking some margin, a 220k resistor is selected. It is named R1 on the PCB board and located just above the battery holder.

To select the voltage divider resistance values, you can use this online calculator.

You can also read this article on battery voltage monitoring.

Step 7: Implimenting Deep Sleep Mode

The heart of the Wemos Board used in our Weather Station is an ESP8266 SOC which is a power hungry chip. Our objective is to run the device by using a 18650 battery but the demand for power usually makes battery operation impractical.

Another problem is that as the device will run continuously, it is quite obvious that the device will experience warming, and therefore the measured temperature will be higher than the ambient temperature.

From the above, it is clear that we have to lower the power consumption of the ESP8266 WiFi chip. To do that, we’ll use the Deep Sleep mode which is the most power efficient option for ESP chip. It allows to put the ESP8266 into hibernation and saves the battery. You can wake up it at regular intervals to make measurements and publish them.

Component Operation mode ----- Sleep mode

1. ESP8266 170 mA -------- 10 uA

2. CH340 12 mA --------- 50 uA

3. Built-in LED 3 mA ----------- 0 uA

4. Voltage monitor 0.006 mA ----- 6 uA


Total185 mA ---- 66 uA

If the sleep-wake cycle is 10 minutes, with a 30 second wake time, the energy consumption budget looks like this:

Wake time 185 mA for 0.5 minutes = 92.5 mA-minutes

Sleep time 0.066 mA for 9.5 minutes = 0.627 mA-minutes

Total in 10 minutes = 93.13 mA-minutes

Thus the average current consumption is 9.3 mA.

Image credit:

Step 8: Selecting the Solar Panel

From the previous step, it is concluded that the average current consumption is 9.3 mA

Charge required for running the device for the whole day = 9.3 mA x 24 Hours = 223.2 mAh

There is no current gain in the linear regulator used in the WeMos, so any current used at 3.3V results in the same current at 3.7V or whatever voltage the battery is at.

The amount of solar insolation varies according to which part of the globe you are located at. To find out the amount of solar insolation in your area, you can use the Global Solar Atlas. By taking consideration into minimum 1 hour of full sunlight, we are going to select the solar panel.

So, our target is to generate 223.2 mAh in 1 hour.

To charge a 3.7V Li-Ion battery, a solar panel of voltage 5 to 6V is adequate.

Required Solar Panel rating = 223.2 mA at a voltage of around 5 to 6 volts.

Solar panel rating = 223.2mA x 5V = 1.1W

Solar Panel Selected : 1W / 5V to 6V

In this project, I have used a 5V,200mA Solar Panel ( 99 x 69 mm)

So a 1W panel should be enough to run the project even in winter in places with a high latitude.

Note: If your location receiving ample amount of sunlight, then a 0.66W solar panel which I have used in my earlier version also work.

Step 9: PCB Design

I have drawn the schematic by using EasyEDA online software after that switched to PCB layout.

All of the components you added in the schematic should be there, stacked on top of each other, ready to be placed and routed. Drag the components by grabbing on its pads. Then place it inside the rectangular border line.

Arrange all the components in such a way that the board occupies minimum space. Smaller the board size, cheaper will be the PCB manufacturing cost. It will be useful if this board has some mounting holes on it so that it can be mounted in an enclosure.

Now you have to route. Routing is the most fun part of this entire process. It’s like solving a puzzle! Using the tracking tool we need to connect all the components. You can use both the top and the bottom layer for avoiding overlap between two different tracks and making the tracks shorter.

You can use the Silk layer to add text to the board. Also, we are able to insert an image file, so I add an image on of my website logo to be printed on the board. At the end using the copper area tool, we need to create the ground area of the PCB.

Now the PCB is ready for manufacturing.

You can order it from PCBWaySign up PCBWay now to get a US $5 coupon. That means your first order is free of cost only you have to pay the shipping charges.

When you place an order, I will get 10% donation from PCBWay for contribution to my work. Your little help may encourage me to do more awesome work in the future. Thank you for your cooperation.

Step 10: PCB Fabrication

Once we are completed the PCB design we just need to click the “Gerber output” button, save the project and we will be able to download the Gerber files which are used to manufacturing the PCB.

Step 11: Assembling the PCB

After receiving the board from the PCB fab house, you have to solder the components.
For Soldering, you will need a decent Soldering Iron, Solder, Nipper.

First I cut the straight male and female headers pin for Wemos Board, TP4056, BMP/E 280 and for all the ports.

Following are the details about the headers :

1. Wemos Board - 2 x 8pins Female

2. BMP280 - 1 x 6pins Female

3. I2C Port - 1 x 4pins

4. Port P1 - 1 x 4pins

5. Port P2- 1 x 3pins

6. Port P3- 1 x 4pins

7. Port P4- 1 x 3 pins

It is good practice to solder the components according to their height. Solder the lesser height components first.

I have started by soldering the resistors, switch and then moved towards the bigger components like headers pin, screw terminal and battery holder.

Step 12: Adding the Modules and Battery

After assembling the header pins, switch and screw terminal, it is time to insert the boards into their respective headers. The headers are clearly labeled on the PCB, so there is no chance of confusion.

First I place the TP4056 board and solder all the pads.

Then I added the Wemos Board and BME280 Sensor.

Finally, I inserted the 18650 battery into the battery holder.

Step 13: Mounting the Standoffs

After adding all the parts, mount the standoffs at 4 corners. I used M3 Brass Hex Standoffs.

Use of standoffs will provide sufficient clearance to the soldering joints and wires from the ground.

Step 14: 3D Printed Enclosure

To give a nice commercial product look, I designed an enclosure for this project. I used Autodesk Fusion 360 to design the enclosure.

The enclosure has two parts:

1. Main Body

2. Cover Lid

The Main Body is basically designed to fit the Weather station V2.0 PCB (85mm* 83mm).

The Cover lid is to cover up the main body opening.

I used my Creality CR-10 printer and 1.75 mm green PLA filament to print the parts. It took me about 11 hours to print the main body and around 3 hours to print the top lid.

My settings are:

Print Speed : 60 mm/s

Layer Height: 0.2mm ( 0.3 also works well)

Fill Density: 25%

Extruder Temperature: 200 deg C

Bed Temp: 60 deg C

Download the STL files from Thingiverse

You can also have a look into the enclosure designed by 3KU_Delta.

Download the STL file of his design from Thingiverse

Step 15: Put the PCB Inside the Enclosure

First, insert the M-F hex standoffs into the four mounting slots in the enclosure.

Then fix the PCB board over the standoffs by aligning its four screw holes at the corner.

After inserting the four standoffs, I have faced difficulty to fix the PCB due to small misalignment. So I am thinking to modify the mounting stand to fix the 3M screw directly instead of hex standoffs.

Step 16: Installing the Components

After mounting the PCB, you have to install the BME280 module and Wemos board.

Then insert the jumper JP2.

Insert the SMA connector into the holes provided in the enclosure. Then tighten the nut along with the washers. Now install the antenna by properly aligning with the SMA connector.

At last, put the 18650 battery inside the battery holder. Make sure you have to insert with the right polarity. The polarity is marked in the battery holder, PCB as well as on the battery.

Step 17: Installing the Solar Panel

Solder a 22 AWG red wire to the positive terminal and black wire to the negative terminal of the Solar panel.

Insert the two wires into the holes in the roof of the main enclosure body.

Use super glue to fix the Solar Panel and press it some time for proper bonding.

Seal the holes from the inside by using hot glue.

Step 18: 3D Printed Stevenson Screen

My earlier enclosure design was a decent looking enclosure but it was not ideal for the weather station. The ideal enclosure for keeping the weather sensors is the Stevenson Screen. A Stevenson screen is an enclosure for weather sensors against rain and direct heat radiation from outside sources, while still allowing air to circulate freely around them.

The Stevenson Screen for Solar Weather Station V2 is designed by my friend Glen. This has a simple wall mount and a 2 part cover to isolate the heat transfer from the solar panel. I really appreciate his work.

You can download the .STL files from Thingiverse

TIP: Spray the fully assembled PCB with Lacquer Spray to protect the board and components, but you do need to put a little tape over the BME280 temp sensor hole to not block it.

Step 19: Interfacing With Blynk App

Step-1: Download the Blynk app

1. For Android

2. For iPhone

Step-2: Get the Auth Token

In order to connect the Blynk App and your hardware, you need an Auth Token.

1. Create a new account in the Blynk App.

2. Press the QR icon on the top menu bar. Create a clone of this Project by scanning the QR code shown above. Once it detected successfully, the whole project will be on your phone immediately.

I've made Sol Weather Station app. You are welcome to try it out!

To start using it: 1. Download Blynk App: or 2. Touch the QR-code icon and point the camera to the code below 3. Enjoy my app!

3. After the project was created, we will send you Auth Token over email.

4. Check your email inbox and find the Auth Token.

Step-3: Preparing Arduino IDE for Wemos Board

To upload the Arduino code to Wemos board, you have to follow this Instructables

Step-4: Arduino Sketch

After installing the above libraries, paste the Arduino code given below.

Enter the auth code from step-1,ssid, and password of your router.

Then upload the code.

Step 20: Uploading Sensor Data to ThingSpeak

First, create an account on ThingSpeak.

Then create a new Channel on your ThingSpeak account.

Find How to Create a New Channel Fill Field 1 as Pressure, Field 2 as Temperature, Field 3 humidity, Field 4 as altitude and Field 5 as Bat Voltage.

In your ThingSpeak account select “Channel” and then “My Channel”.

Click on your channel name.

Click on “API Keys” tab and copy the “Write API Key”

Open the Solar_Weather_Station_ThingSpeak code.

Replace the “WRITE API ”with the copied “Write API Key”.

You can see my live feed.

Currently, I am getting an inconsistent reading for battery voltage, so the field is disabled.

Step 21: Software and Libraries

To use Wemos D1 with the Arduino library, you'll have to use the Arduino IDE with ESP8266 board support. If you haven't already done that yet, you can easily install ESP8266 Board support to your Arduino IDE by following this tutorial by Sparkfun.

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


Before uploading the code install the following libraries :

1. ESP8266

2. BMP280

3. Blynk

You can read this tutorial by Sparkfun to install the Arduino libraries.

In my earlier version, there are two separate codes for Blynk and Thinspeak but in this version, we have written a single piece of code. The user has to only comment out a single line of code for Blynk or Thingspeak. For example, if you are using it for Blynk App, the code should be as below:

   const String App = "BLYNK";         //  alternative is line below
// const String App = "Thingspeak";    //  alternative is line above

Credit: I want to give a lot of credit to Keith Hungerford, who has guided me to make this project more powerful. The software library for BMP280 is also written by him. You can read his Instructable on BMP280 power saving mode.

Note: Before using the deep sleep feature, Wemos D0 pin must be connected to the RST pin. This can be done by shorting the jumper JP2.

Update : 15.05.2019

You can also see excellent work done by 3KUdelta on his GitHub Page. In his V2.3 code, he included the famous Zambretti forecaster. I really appreciate his hard work for the improvement of the project.

The software provides short term forecast in words (4-6 hours) using the famous Zambretti forecast model :

  • 4-6 hour forecast in words
  • Trend in words
  • Temperature
  • Dewpoint
  • Heat Index
  • Humidity
  • Absolute Pressure
  • Relative Pressure
  • Battery Voltage (V)

Step 22: Conclusion

Today I have received the Solar Panel and installed it. I really love the final outcome of the project.

In future, my plan is to add wind and rainfall measuring sensors like this project .

I am thinking to make a DIY kit for this project, but not finding a suitable vendor who can do this for me. Be in touch for more updates.

Update on 15.02.2019 :

Now you can order the PCB from PCBWay
Sign up PCBWay now to get a US $5 coupon. That means your first order is free of cost only you have to pay the shipping charges. When you place an order, I will get 10% donation from PCBWay for contribution to my hard work. Your little help may encourage me to do more awesome work in the future. Thank you for cooperation.

Thanks for reading my Instructable.

If you like my project, don't forget to share it.

Comments and feedback are always welcome.

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181 Discussions


Question 18 days ago

Could you elaborate on the I2C pinout labels on the pcb silkscreen? I bought an Adafruit BME280, unfortunately the pinout doesn't map seamlessly:

VCC -> VIN // 3-5VDC in
SCL ? -> SCK // clock ?
SDA ? -> SDI // data in ?
CSB ? -> CS // chip select ?


6 answers

Answer 15 days ago

Hi jay-thomas, I think you have what you need with the answer from @Topspliff, but I want to add a little bit.
This Adafruit board design provides some extra features which are not needed in this project, and a different pin order to every other board I have managed to find on the internet. All the other designs are (more or less) compatible with the PCB layout, but not the Adafruit one.
This Adafruit board provides its own voltage regulator on board, and also level shifting so you can use it directly in a 5Volt environment, even though the BME280 is a 3.3 Volt component. For this project, which is essentially 3.3V powered, these facilities are not needed.
Here is a bit of extra information about connections.
The labelling on the Adafruit BME280 board is for the SPI interface, which is not used in this project which uses I2C. That is why the names are a bit different. There is no issue with it working in either SPI or I2C mode (but see below).
The VCC on the PCB should go to the 3Vo pin on the Adafruit BME board, bypassing the regulator on the board which will only lose you a bit of voltage and maybe make the sensor not work at low battery charge levels.
The GND, SCL (SCK) and SDA (SDI) connections need no further comment. They are correct in your message.
The CS pin on the Adafruit BME280 board should be connected to Vcc (ie 3.3V), which on the PCB is done by connecting to the CSB position. This is actually important, because if the BME280 device on the board detects anything other than Vcc on this pin it goes into SPI mode, which you do not want. You may get away with leaving this pin not connected, but this may give you problems and it is much better to connect it to Vcc.
The SDO pin on the Adafruit BME280 should also be connected. If you connect it to Ground (which is what is on SDO of the PCB) the I2C address of the sensor will be 0x76. It is also valid to connect SDO on the sensor to Vcc, in which case the I2C address of the sensor will be 0x77. You probably do not need this but it allows you to have a second sensor connected.
So I recommend you make the connections exactly as per your message, but with the clarification that Vcc should go to the "3Vo" pin on the sensor board.
I hope this helps.


Reply 14 days ago

The VCC on the PCB should go to the 3Vo pin on the Adafruit BME board,
bypassing the regulator on the board which will only lose you a bit of
voltage and maybe make the sensor not work at low battery charge levels.
The 3v out on the Adafruit will take 3v in? Won't that have to pass through the voltage regulator in reverse and possibly cause issues? Maybe be stopped by a diode?

It is also valid to connect SDO on the sensor to Vcc, in which case the
I2C address of the sensor will be 0x77. You probably do not need this
but it allows you to have a second sensor connected.
That's a good point. I do want to be able to utilize the additional
ports like P2 for a DS18B20. This is a detail I would have missed if you
didn't mention it.

So my working pinout sounds like it should be like in the image I've attached.


Reply 14 days ago

Hi jay-thomas,
re VIN vs 3Vo: you CAN use either. I checked the schematic, the regulator is a MIC5225-3.3. It has a dropout voltage of 0.23 volts at a current of 50 mA, so that is the voltage drop you will get from the supply voltage to the sensor when the supply voltage is lower than 3.3V. When reverse biased, it will draw 5 microamps, which you can regard as a virtual zero. The 3Vo pin connects directly to all the operational circuitry on the board, including the sensor, so it can be used to supply power to the board no problems. I attach the schematic FYI.
Re SDO connection: Your diagram (very nice diagram by the way) indicates SDO on the weather station PCB with "N.C.". Since It is connected to Vcc, IF it was more convenient for your cross-connection wiring, you can make the connection SDO to SDO.
You only need to use the Ground option for SDO if you want a second BME280 (or a BMP280 which uses the same I2C address). You can add a DS18B20 or the like on other ports without considering the I2C address space. It is only when adding more I2C devices on the same I2C port that you need to consider possible address conflicts.


Reply 14 days ago

Thank you so much for taking the time to clarify the inner-workings on this sensor and SPI vs I2C. I can't wait to get out the crimper and build a harness for this, and I will keep SDO -> SDO since it won't interfere with sensors I put on other channels.

Best regards.


Answer 17 days ago

Hi Jay-Thomas

You are correct, the BME bourd you have is not the standard board on the internet, you got the more "expensive" one, however it will still work.

VCC -> VIN // 3-5VDC in
SCL ? -> SCK // clock : correct
SDA ? -> SDI // data in : correct
CSB ? -> CS // chip select : not needed
SDO -> SDO : not needed

As your board has a different pin alignment, just use long wires soldered to your BME and plug them in the main PCB


Reply 17 days ago

Topspliff: let me say on behalf on newbies like me, comments like yours are a godsend when we get stuck. I will solder a JST connector on the board and wire it accordingly.


Question 2 months ago

Hello Community,
I´ve got a question. How can i integrate another sensor - in my case a DS18B20 - into the sketch? Does anyone have an example? I would like to use it with blynk.

Thank you and have a nice day!

4 answers

Answer 2 months ago

Hi GerritK4

OK all done and works great, I have used the DS18B20 as a pool temp sensor to go along with my BME280, I`m not using the pressure reading so used the spare gauge to display my pool temperature.

If you look at the code I used D7 as the pin to read the sensor.
You also need to download the Dallas library.
I also shortened the code right down to basics.

Any problems ping me back.

Hope this is of help to anyone else out there, cheers

#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include <BlynkSimpleEsp8266.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#define ONE_WIRE_PIN D7
OneWire oneWire(ONE_WIRE_PIN);
DallasTemperature sensors(&oneWire);
Adafruit_BME280 bme;

void setup() {

Blynk.begin("Blynk code", "WiFi SSID", "WiFi Password");
Adafruit_BME280::FILTER_OFF );
//delayTime = 60000;
void loop() {
void measurementEvent() {


float temperature = bme.readTemperature();
temperature = temperature + -2 ;
float humi = bme.readHumidity();
float pool = (sensors.getTempCByIndex(0));

// Voltage divider R1 = 220k+100k+220k =540k and R2=100k
float calib_factor = 5.28; // change this value to calibrate the battery voltage
unsigned long raw = analogRead(A0);
float volt = raw * calib_factor / 1024;

Blynk.virtualWrite(0, temperature); // virtual pin 0
Blynk.virtualWrite(1, humi); // virtual pin 1
Blynk.virtualWrite(2, pool); // virtual pin 2
Blynk.virtualWrite(3, volt); // virtual pin 3

void goToSleep() {
ESP.deepSleep(5 * 60 * 1000000);


Reply 6 weeks ago

Thank you for your help. I was very busy in the last weeks and could try it now. If i need help i will ping you.


Reply 17 days ago

thank you for the information, just to be clear.
From the DS18B20 I have 3 wires, black, red and yellow.
if I understand correctly:
black -> GND
yellow -> D7
red -> vss
is this correct?


Reply 17 days ago

Yes Pichirichi that is correct, you will also need a 4k7 or 10k resistor between yellow/D7 and vss


Question 19 days ago

How can I connect this home weather station to my Google home mini? And also assistant?


25 days ago

I finished this project yesterday. Most everything went smoothly except for the voltage monitoring.

I am getting 5.28 V every single reading. The raw value must be 1024. I looked at the data that came in overnight on Thingspeak and it was 5.28 V every single reading. When I had the Wemos on my breadboard with just the sensor, I was getting floating readings for voltage from 0.02 V to 0.07 V. I take it to mean that A0's wires on the Wemos itself are not crossed.

I inspected the main circuit board for solder bridges near A0, namely RST and D0. I think if there was a bridge to RST I would have a lot of problems, but maybe D0 is the culprit. I could not see a bridge this morning.

Oh and there is 220k resistor as you specified. Before soldering it, I made sure that it was the right value with the color codes. I did not, however, test it with a multimeter. I'll try that next but I expect it's fine.

Suggestions are most welcome! I'm not the best with electronics.

Oh, I also ported this to MicroPython. I haven't put it on GitHub yet but that is the plan -- I want to clean up the cruft first. I added MQTT and it listens for a 'pause' event so the code will stop and the system can be modified.


EDIT: I had a 220 Ohm resistor instead of a 220 KOhm resistor. I switched this out and I'm getting decent readings now. I also took a voltage reading with my multimeter and changed the calibration factor in the code to 5.1315.


Question 6 weeks ago

First of all, super project!
I have successfully 3D printed, ordered parts and PCB and assembled.

Now i want to add a moisture sensor, but I cannot figure out how to get it to work by adding readings to serial monitor or thingspeak.

What and where do i need to add some code? Any libraries I need to download?

My sensor:
My thingspeak:

2 answers

Answer 4 weeks ago

Hi staxen, The link for the sensor took me to an aliexpress page. Is that correct? It shows the sensor itself (that goes in the ground) plus an electronics module and some connecting wires. Do you have the complete package, or only the sensor itself?
As I understand it, this sensor provides two outputs, one analog (labelled A0) and one digital (labelled D0). The electronics module presumably senses the analog voltage on A0 and applies a threshold to it. Below the threshold D0 will be low, above it will be high. The pot allows you to adjust the point at which the change occurs.
To use the analog output, you really need an ADC input on your microcontroller. The WeMos D1 mini pro used in this project only has 1 ADC input, which is used to measure the battery voltage. You would either need to give up that function, add an external ADC such as an ADS1115, which would connect to the I2C interface.
To use the digital output, that can be connected to one of the ports provided on the PCB, such as Port 2 which gives you access to digital pin D8.
If you let me know what your hardware is going to look like, we can then talk about software.


Reply 4 weeks ago

Hi Keith

Thanks for the feedback.

It's correct that the link is for a sensor on the Ali supermarket, I'm planning to use it to meassure soil moisture in the garden.
I think I made a quick fix by using ESP easy as the code for the D1 Mini, and soldering an extra cable on top of the A0 pin, and the ESP easy cannot meassure voltage so thats probably why it seems to work.
I will look into you other suggestions, it would be nice to have both the battery feature and soil moisture on the same setup :)


4 weeks ago

Hi, is there any chance in next pcb update to add 3V3, GND, TX, RX connector to connect e.g. sigfox modem for sending data to long range?


2 months ago

Hiya! Do you think that PCB could be made one-sided? We have a Bantam Mill at my school and I'm thinking about doing this project with a student, haven't totally gone under the hood looking at the PCB yet...