ESP32 Project #4: BMP280 Sensor

Hello! I’m back. On this project I’ll show you how external sensor: BMP280 sensor works. BMP280 is a humidity, temperature, and pressure sensor.

Let’s try!

Parts and components

• Arduino IDE
• ESP32 Board
• Breadboard
• Jumper wires
• BMP280 sensor
• USB cable

Schematic (www.circuitschools.com)

Follow the schematic above then setup the BMP280 package. Go to Tools > Manage Libraries then search for “BMP 280”. Install the Adafruit BMP280 Library.

Tools > Manage Libraries > BMP280

To test the sketch, go to File > Examples > Adafruit BMP280 Library > bmp280test. Connect the ESP32 with the PC then verify and upload the sketch.

This is the bmp280test.

/***************************************************************************
  This is a library for the BMP280 humidity, temperature & pressure sensor
Designed specifically to work with the Adafruit BMP280 Breakout
  ----> http://www.adafruit.com/products/2651
These sensors use I2C or SPI to communicate, 2 or 4 pins are required
  to interface.
Adafruit invests time and resources providing this open source code,
  please support Adafruit andopen-source hardware by purchasing products
  from Adafruit!
Written by Limor Fried & Kevin Townsend for Adafruit Industries.
  BSD license, all text above must be included in any redistribution
 ***************************************************************************/
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_BMP280.h>
#define BMP_SCK  (13)
#define BMP_MISO (12)
#define BMP_MOSI (11)
#define BMP_CS   (10)
Adafruit_BMP280 bmp; // I2C
//Adafruit_BMP280 bmp(BMP_CS); // hardware SPI
//Adafruit_BMP280 bmp(BMP_CS, BMP_MOSI, BMP_MISO,  BMP_SCK);
void setup() {
  Serial.begin(9600);
  Serial.println(F("BMP280 test"));
if (!bmp.begin()) {
    Serial.println(F("Could not find a valid BMP280 sensor, check wiring!"));
    while (1);
  }
/* Default settings from datasheet. */
  bmp.setSampling(Adafruit_BMP280::MODE_NORMAL,     /* Operating Mode. */
                  Adafruit_BMP280::SAMPLING_X2,     /* Temp. oversampling */
                  Adafruit_BMP280::SAMPLING_X16,    /* Pressure oversampling */
                  Adafruit_BMP280::FILTER_X16,      /* Filtering. */
                  Adafruit_BMP280::STANDBY_MS_500); /* Standby time. */
}
void loop() {
    Serial.print(F("Temperature = "));
    Serial.print(bmp.readTemperature());
    Serial.println(" *C");
Serial.print(F("Pressure = "));
    Serial.print(bmp.readPressure());
    Serial.println(" Pa");
Serial.print(F("Approx altitude = "));
    Serial.print(bmp.readAltitude(1013.25)); /* Adjusted to local forecast! */
    Serial.println(" m");
Serial.println();
    delay(2000);
}

I uploaded the sketch then opened Serial Monitor. What? Nothing showed. Hmm, what’s wrong? I tried to solve the problem and found this code to find the I2C address for BMP280 sensor.

#include <Wire.h> //include Wire.h library
 
void setup()
{
  Wire.begin(); // Wire communication begin
  Serial.begin(9600); // The baudrate of Serial monitor is set in 9600
  while (!Serial); // Waiting for Serial Monitor
  Serial.println("\nI2C address Scanner CircuitSchools.com");
}
 
void loop()
{
  byte error, address; //variable for error and I2C address
  int devicecount;
 
  Serial.println("Scanning...");
 
  devicecount = 0;
  for (address = 1; address < 127; address++ )
  {
    // The i2c_scanner uses the return value of
    // the Write.endTransmisstion to see if
    // a device did acknowledge to the address.
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
 
    if (error == 0)
    {
      Serial.print("I2C device found at address 0x");
      if (address < 16)
        Serial.print("0");
      Serial.print(address, HEX);
      Serial.println("  !");
      devicecount++;
    }
    else if (error == 4)
    {
      Serial.print("Unknown error at address 0x");
      if (address < 16)
        Serial.print("0");
      Serial.println(address, HEX);
    }
  }
  if (devicecount == 0)
    Serial.println("No I2C devices found\n");
  else
    Serial.println("done\n");
 
  delay(5000); // wait 5 seconds for the next I2C scan
}

I uploaded the sketch, but…

No I2C devices found

I found the discussion on my class that there are some reasons for this. Either the sensor was broken, not soldered well, or the code. Then I found a comment by my course assistant to change the Wire.begin() to Wire.begin(21,22) as SDA was on 21 and SCL on 22. But still…

No I2C devices found

I tried to change the pin to 23 and 19 but still not working. I guess something was wrong with the sensor. Maybe it was not soldered well, or broken(?). I ordered the soldered one tho… :(

Final say

Sadly I couldn’t finish this project. But, I learned about BMP280, what supposed to be shown on the serial monitor, and the problem of my experiment. I will try a bit more to solve this problem. Let’s hope for the best!