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ESP32 and GY-21P data to Thingspeak example

by shedboy71

In this example we connect a GY-21P sensor to an ESP32 and then we will upload the data to Thingspeak

The GY-21P combines a BMP280 sensor and an SI7021 sensor. The on-board BMP280+SI7021 sensor measures atmospheric pressure from 30kPa to 110kPa as well as relative humidity and temperature. Perfect for a weather station

Thingspeak setup

You will now need to create a new account at thingspeak – https://thingspeak.com. Once done create a new channel and add one new field called temperature. You can see this in a screen capture of my simple channel, notice the ChannelID you will need that in your code later.

You can also fill in other fields such as Name, description and there are a few others as well. The key one(s) are Field1, Field 2 , Field 3, Field 4 and Field 5 – this effectively is the data you send to thingspeak

GY-21P setup in thingspeak

GY-21P setup in thingspeak

Parts List

Name Link
ESP32
GY-21P
Connecting cables

 

Schematics/Layout

Connect the sensor to the ESP32

esp32 and GY21P

esp32 and GY21P

Code

I use a variety of Adafruit libraries and also the Thingspeak libraries for this example

https://github.com/adafruit/Adafruit_Sensor

https://github.com/adafruit/Adafruit_BMP280_Library

https://github.com/adafruit/Adafruit_Si7021

https://github.com/mathworks/thingspeak-arduino

I got the sea level pressure value from this link

#include "ThingSpeak.h"
#include <WiFi.h>
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP280.h>
#include "Adafruit_Si7021.h"

char ssid[] = "networkssid"; // your network SSID (name)
char pass[] = "networkpassword"; // your network password
int keyIndex = 0; // your network key Index number (needed only for WEP)
WiFiClient client;

unsigned long myChannelNumber = 000000; //update
const char * myWriteAPIKey = "yourapikey"; //update

Adafruit_BMP280 bmp; // I2C
Adafruit_Si7021 sensor = Adafruit_Si7021();

void setup()
{
Serial.begin(115200); //Initialize serial
if (!bmp.begin())
{
Serial.println("Could not find a valid BMP280 sensor, check wiring!");
while (1);
}

if (!sensor.begin())
{
Serial.println("Did not find Si7021 sensor!");
while (true);
}
delay(10);
WiFi.mode(WIFI_STA);
ThingSpeak.begin(client); // Initialize ThingSpeak

}

void loop() {

// Connect or reconnect to WiFi
if(WiFi.status() != WL_CONNECTED){
Serial.print("Attempting to connect to SSID: ");
//Serial.println(SECRET_SSID);
while(WiFi.status() != WL_CONNECTED){
WiFi.begin(ssid, pass); // Connect to WPA/WPA2 network. Change this line if using open or WEP network
Serial.print(".");
delay(5000);
}
Serial.println("\nConnected.");
}

float bmpPressure = bmp.readPressure();
float bmpTemperaturee = bmp.readTemperature();
float bmpAltitude = bmp.readAltitude(1024);
float siHumidity = sensor.readHumidity();
float siTemperature = sensor.readTemperature();
// Write to ThingSpeak. There are up to 8 fields in a channel, allowing you to store up to 8 different
// pieces of information in a channel.
ThingSpeak.setField(1, bmpPressure);
ThingSpeak.setField(2, bmpTemperaturee);
ThingSpeak.setField(3, bmpAltitude);
ThingSpeak.setField(4, siHumidity);
ThingSpeak.setField(5, siTemperature);

// write to the ThingSpeak channel
int x = ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);
if(x == 200){
Serial.println("Channel update successful.");
}
else{
Serial.println("Problem updating channel. HTTP error code " + String(x));
}

delay(20000); // Wait 20 seconds to update the channel again
}

Output

Open the serial monitor and verify you are connecting and the data has been successfully

Attempting to connect to SSID: .
Connected.
Channel update successful.
Channel update successful.
Channel update successful.
Channel update successful.
Channel update successful.

Lets look at our Thingspeak channel, all going well you should see data like the following

GY21P and Thingspeak data

GY21P and Thingspeak data

Links

 

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Code

ESP32 and GY-21P readings on a web page

by shedboy71

In this example we connect a GY-21P sensor to an ESP32 and then we will display the readings on a webpage

Lets recap the GY-21P module which spoke about in a previous article

The GY-21P is an interesting module in that it combines a BMP280 sensor and an SI7021 sensor. The on-board BMP280+SI7021 sensor measures atmospheric pressure from 30kPa to 110kPa as well as relative humidity and temperature.

BMP280
Pressure range: 300-1100 hPa (9000 meters above sea level at -500m)
Relative accuracy (at 950 – 1050 hPa at 25 ° C): ± 0.12 hPa, equiv. to ± 1 m
Absolute accuracy (at (950 – 1050 hPa, 0 – +40 ° C): ± 0.12 hPa, equiv. To ± 1 m
Mains voltage: 1.8V – 3.6V
Power consumption: 2.7µA at 1Hz readout rate
Temperature range: -40 to + 85 ° C

SI7021
HVAC/R
Thermostats/humidistats
Respiratory therapy
White goods
Indoor weather stations
Micro-environments/data centers
Automotive climate control and defogging
Asset and goods tracking
Mobile phones and tablets
Size: 1.3*1cm/0.51*0.39″

Features:

Operation Voltage: 3.3V
I2C & SPI Communications Interface
Temp Range: -40C to 85C
Humidity Range: 0 – 100% RH, =-3% from 20-80%
Pressure Range: 30,000Pa to 110,000Pa, relative accuracy of 12Pa, absolute accuracy of 100Pa
Altitude Range: 0 to 30,000 ft (9.2 km), relative accuracy of 3.3 ft (1 m) at sea level, 6.6 (2 m) at 30,000 ft.

Parts List

Name Link
ESP32
GY-21P
Connecting cables

 

Schematics/Layout

Connect the sensor to the ESP32

esp32 and GY21P

esp32 and GY21P

Code

I use a variety of Adafruit libraries, took the default examples and made the following out of them

https://github.com/adafruit/Adafruit_Sensor

https://github.com/adafruit/Adafruit_BMP280_Library

https://github.com/adafruit/Adafruit_Si7021

I got the sea level pressure value from this link

#include <WiFi.h>
#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP280.h>
#include "Adafruit_Si7021.h"

const char* ssid = "yourname";
const char* password = "yourpasssword";

Adafruit_BMP280 bmp; // I2C
Adafruit_Si7021 sensor = Adafruit_Si7021();
WiFiServer server(80);

void setup()
{
Serial.begin(115200);
pinMode(5, OUTPUT); // set the LED pin mode
if (!bmp.begin())
{
Serial.println("Could not find a valid BMP280 sensor, check wiring!");
while (1);
}

if (!sensor.begin())
{
Serial.println("Did not find Si7021 sensor!");
while (true);
}
delay(10);

// We start by connecting to a WiFi network

Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}

Serial.println("");
Serial.println("WiFi connected.");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());

server.begin();

}

int value = 0;

void loop(){
WiFiClient client = server.available(); // listen for incoming clients

if (client)
{ // if you get a client,
Serial.println("New Client."); // print a message out the serial port
String currentLine = ""; // make a String to hold incoming data from the client
while (client.connected())
{ // loop while the client's connected
if (client.available())
{ // if there's bytes to read from the client,
char c = client.read(); // read a byte, then
Serial.write(c); // print it out the serial monitor
if (c == '\n')
{ // if the byte is a newline character

// if the current line is blank, you got two newline characters in a row.
// that's the end of the client HTTP request, so send a response:
if (currentLine.length() == 0)
{
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connnection: close");
client.println();
client.println("<!DOCTYPE HTML>");
client.println("<html>");
client.println("<meta http-equiv=\"refresh\" content=\"5\">");
client.println("<br />");
//bmp280 part
client.println("<h3>BMP280 readings</h3>");
client.print("Pressure (Pa): ");
client.println((float)bmp.readPressure(), 1);
client.println("<br />");
client.print("Temperature (C): ");
client.println((float)bmp.readTemperature(), 1);
client.println("<br />");
client.print("Altitude (m): ");
client.println((float)bmp.readAltitude(1024), 1); // this should be adjusted to your local forcase
client.println("<br />");
//SI7021 part
client.println("<h3>SI7021 readings</h3>");
client.print("Humidity (%): ");
client.println((float)sensor.readHumidity(), 1);
client.println("<br />");
client.print("Temperature (C): ");
client.println((float)sensor.readTemperature(), 1);
client.println("<br />");

client.println("</html>");
break;
// break out of the while loop:
break;
}
else
{ // if you got a newline, then clear currentLine:
currentLine = "";
}
}
else if (c != '\r')
{ // if you got anything else but a carriage return character,
currentLine += c; // add it to the end of the currentLine
}
}
}
// close the connection:
client.stop();
Serial.println("Client Disconnected.");
}
}

 

Output

OPen the serial monitor and take a note of the IP address

Open your favourite web browser and type in the IP address from above, you should see something like this

gy-21p output

gy-21p output

Links

 

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Code

ESP32 and GY-21P module

by shedboy71

The GY-21P is an interesting module in that it combines a BMP280 sensor and an SI7021 sensor. The on-board BMP280+SI7021 sensor measures atmospheric pressure from 30kPa to 110kPa as well as relative humidity and temperature.

BMP280
Pressure range: 300-1100 hPa (9000 meters above sea level at -500m)
Relative accuracy (at 950 – 1050 hPa at 25 ° C): ± 0.12 hPa, equiv. to ± 1 m
Absolute accuracy (at (950 – 1050 hPa, 0 – +40 ° C): ± 0.12 hPa, equiv. To ± 1 m
Mains voltage: 1.8V – 3.6V
Power consumption: 2.7µA at 1Hz readout rate
Temperature range: -40 to + 85 ° C

SI7021
HVAC/R
Thermostats/humidistats
Respiratory therapy
White goods
Indoor weather stations
Micro-environments/data centers
Automotive climate control and defogging
Asset and goods tracking
Mobile phones and tablets
Size: 1.3*1cm/0.51*0.39″

Features:

Operation Voltage: 3.3V
I2C & SPI Communications Interface
Temp Range: -40C to 85C
Humidity Range: 0 – 100% RH, =-3% from 20-80%
Pressure Range: 30,000Pa to 110,000Pa, relative accuracy of 12Pa, absolute accuracy of 100Pa
Altitude Range: 0 to 30,000 ft (9.2 km), relative accuracy of 3.3 ft (1 m) at sea level, 6.6 (2 m) at 30,000 ft.

Code

I use a variety of Adafruit libraries, took the default examples and made the following out of them

https://github.com/adafruit/Adafruit_Si7021

https://github.com/adafruit/Adafruit_BMP280_Library

https://github.com/adafruit/Adafruit_Sensor

[cpp]

include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP280.h>
#include “Adafruit_Si7021.h”

Adafruit_BMP280 bme; // I2C
Adafruit_Si7021 sensor = Adafruit_Si7021();

void setup()
{
Serial.begin(9600);
Serial.println(“BMP280 and SI7021 (GY-21p) test”);

if (!bme.begin())
{
Serial.println(“Could not find a valid BMP280 sensor, check wiring!”);
while (1);
}

if (!sensor.begin())
{
Serial.println(“Did not find Si7021 sensor!”);
while (true);
}
}

void loop()
{
Serial.println(“BMP280 results”);
Serial.print(“Temperature = “);
Serial.print(bme.readTemperature());
Serial.println(” *C”);
Serial.print(“Pressure = “);
Serial.print(bme.readPressure());
Serial.println(” Pa”);
Serial.print(“Approx altitude = “);
Serial.print(bme.readAltitude(1013.25)); // this should be adjusted to your local forcase
Serial.println(” m”);
Serial.println();

Serial.println(“SI7021 results”);
Serial.print(“Humidity: “);
Serial.println(sensor.readHumidity(), 2);
Serial.print(“Temperature: “);
Serial.println(sensor.readTemperature(), 2);
Serial.println();
delay(2000);
}

[/cpp]

Output

OPen the serial monitor

BMP280 results
Temperature = 27.26 *C
Pressure = 99042.63 Pa
Approx altitude = 191.78 m

SI7021 results
Humidity: 31.04
Temperature: 27.30

BMP280 results
Temperature = 28.43 *C
Pressure = 99044.82 Pa
Approx altitude = 191.60 m

SI7021 results
Humidity: 32.59
Temperature: 28.56

BMP280 results
Temperature = 28.17 *C
Pressure = 99037.41 Pa
Approx altitude = 192.22 m

SI7021 results
Humidity: 32.88
Temperature: 28.46

You can see the temperature output is close between the sensors

 

Links

Atmospheric Humidity Temperature Sensor Breakout Barometric Pressure BMP280 SI7021 for Arduino

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Code

ESP32 and Si7021 temperature sensor example

by shedboy71

The  Si7021  I2C Humidity  and  Temperature  Sensor  is  a  monolithic  CMOS  IC integrating   humidity   and   temperature   sensor   elements,   an   analog-to-digital converter, signal processing, calibration data, and an I2C Interface. The Si7021 offers an accurate, low-power, factory-calibrated digital solution ideal for measuring humidity, dew-point, and temperature, in applications ranging from HVAC/R and asset tracking to industrial and consumer platforms.

Si7021

Si7021

Features

Precision Relative Humidity Sensor ± 3% RH (max), 0–80% RH
High Accuracy Temperature Sensor ±0.4 °C (max), –10 to 85 °C
0 to 100% RH operating range
Up to –40 to +125 °C operating range
Wide operating voltage – (1.9 to 3.6 V)
Low Power Consumption – 150 μA active current

Parts Required

Here are the parts I used

 

Name Link
ESP32
Si7021
Connecting cables

Connection

esp32 and si7021

esp32 and si7021

Code

No 3rd party libraries required

 

#include <Wire.h>

// SI7021 I2C address is 0x40(64)
#define si7021Addr 0x40

void setup()
{
  Wire.begin();
  Serial.begin(9600);
  Wire.beginTransmission(si7021Addr);
  Wire.endTransmission();
  delay(300);
}

void loop()
{
  unsigned int data[2];
  
  Wire.beginTransmission(si7021Addr);
  //Send humidity measurement command
  Wire.write(0xF5);
  Wire.endTransmission();
  delay(500);
    
  // Request 2 bytes of data
  Wire.requestFrom(si7021Addr, 2);
  // Read 2 bytes of data to get humidity
  if(Wire.available() == 2)
  {
    data[0] = Wire.read();
    data[1] = Wire.read();
  }
    
  // Convert the data
  float humidity  = ((data[0] * 256.0) + data[1]);
  humidity = ((125 * humidity) / 65536.0) - 6;

  Wire.beginTransmission(si7021Addr);
  // Send temperature measurement command
  Wire.write(0xF3);
  Wire.endTransmission();
  delay(500);
    
  // Request 2 bytes of data
  Wire.requestFrom(si7021Addr, 2);
  
  // Read 2 bytes of data for temperature
  if(Wire.available() == 2)
  {
    data[0] = Wire.read();
    data[1] = Wire.read();
  }

  // Convert the data
  float temp  = ((data[0] * 256.0) + data[1]);
  float celsTemp = ((175.72 * temp) / 65536.0) - 46.85;
  float fahrTemp = celsTemp * 1.8 + 32;
   
  // Output data to serial monitor
  Serial.print("Humidity : ");
  Serial.print(humidity);
  Serial.println(" % RH");
  Serial.print("Celsius : ");
  Serial.print(celsTemp);
  Serial.println(" C");
  Serial.print("Fahrenheit : ");
  Serial.print(fahrTemp);
  Serial.println(" F");
  delay(1000);
}

 

Testing

Open the serial monitor and you should see something like this

Humidity : 44.89 % RH
Celsius : 21.07 C
Fahrenheit : 69.93 F
Humidity : 45.25 % RH
Celsius : 22.14 C
Fahrenheit : 71.86 F
Humidity : 47.32 % RH
Celsius : 26.53 C
Fahrenheit : 79.76 F
Humidity : 49.03 % RH
Celsius : 28.33 C
Fahrenheit : 83.00 F
Humidity : 50.74 % RH
Celsius : 29.26 C
Fahrenheit : 84.66 F

 

Link

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