ESP32 and BMP183 temperature sensor example

In this article we look at a BMP183 sensor which is another temperature sensor. We will have some info on the sensor, schematics and code example using the Arduino IDE

Lets look at some information regarding the sensor from the manufacturer

The BMP183 is the function compatible successor of the BMP085, a new generation of high precision digital pressure sensors for consumer applications.

The ultra-low power, low voltage electronics of the BMP183is optimized for use in mobile phones, PDAs, GPS navigation devices and outdoor equipment.

With a low altitude noise of merely 0.25m at fast conversion time, the BMP183 offers superior performance.

The SPI interface allows for easy system integration with a microcontroller. The BMP183is based on piezo-resistive technology for EMC robustness, high accuracy and linearity as well as long term stability.

Key features

Pressure range : 300 … 1100hPa (+9000m… -500m relating to sea level)

Supply voltage:
1.8 … 3.6V (VDD)
1.62V … 3.6V (VDDIO)

Low power : 5μA at 1 sample / sec. in standard mode
Low noise : 0.06hPa (0.5m)in ultra low power mode 0.02hPa (0.17m) ultra high resolution mode

Parts Required

Name	Link
ESP32		Aliexpress link Amazon Ebay
BMP183
Connecting cables		Aliexpress link Amazon Ebay

Schematic/Connection

This is an SPI sensor, so a little more complicated to connect than an I2C one

SCK – This is the SPI Clock pin, its an input to the chip
SDO – this is the Serial Data Out / Master In Slave Out pin
SDI – this is the Serial Data In / Master Out Slave In pin
CS – this is the Chip Select pin

By default, the pin mapping for SPI is:

esp32 and BMP183 layout

Code Example

This uses the library from https://github.com/adafruit/Adafruit_BMP183_Library

You can download it and install it via the IDE or use the library manager. I used Hardware SPI in this example

[codesyntax lang=”cpp”]

#include <SPI.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BMP183.h>

// For hardware SPI:
// Connect SCK to SPI Clock, SDO to SPI MISO, and SDI to SPI MOSI
// See  http://arduino.cc/en/Reference/SPI for your Arduino's SPI pins!
// On UNO, Clock is #13, SDO/MISO is #12 and SDI/MOSI is #11

// You can also use software SPI and define your own pins!
// #define BMP183_CLK  18
// #define BMP183_SDO  19  // AKA MISO
// #define BMP183_SDI  22  // AKA MOSI

// You'll also need a chip-select pin, use any pin!
#define BMP183_CS   5

// initialize with hardware SPI
Adafruit_BMP183 bmp = Adafruit_BMP183(BMP183_CS);
// or initialize with software SPI and use any 4 pins
//Adafruit_BMP183 bmp = Adafruit_BMP183(BMP183_CLK, BMP183_SDO, BMP183_SDI, BMP183_CS);

/**************************************************************************/
/*
    Arduino setup function (automatically called at startup)
*/
/**************************************************************************/
void setup(void) 
{
  Serial.begin(9600);
  Serial.println("BMP183 Pressure Sensor Test"); Serial.println("");
  
  /* Initialise the sensor */
  if(!bmp.begin())
  {
    /* There was a problem detecting the BMP183 ... check your connections */
    Serial.print("Ooops, no BMP183 detected ... Check your wiring!");
    while(1);
  }
}

/**************************************************************************/
/*
    Arduino loop function, called once 'setup' is complete (your own code
    should go here)
*/
/**************************************************************************/
void loop(void) 
{
    /* Display atmospheric pressue in Pascals */
    Serial.print("Pressure:    ");
    Serial.print(bmp.getPressure());
    Serial.print(" Pascals / ");
    Serial.print(bmp.getPressure() / 100);
    Serial.println(" millibar (hPa)");

    /* First we get the current temperature from the BMP085 */
    float temperature;
    temperature = bmp.getTemperature();
    Serial.print("Temperature: ");
    Serial.print(temperature);
    Serial.println(" C");
    
    /* Calculating altitude with reasonable accuracy requires pressure    *
     * sea level pressure for your position at the moment the data is     *
     * converted. If you don't have these values, a 'generic' value of    *
     * 1013.25 mbar can be used (defined as SENSORS_PRESSURE_SEALEVELHPA  *
     * in sensors.h), but this isn't ideal and will give variable         *
     * results from one day to the next.                                  *
     *                                                                    *
     * You can usually find the current SLP value by looking at weather   *
     * websites or from environmental information centers near any major  *
     * airport.                                                           *
     *                                                                    *
     * For example, for Paris, France you can check the current mean      *
     * pressure and sea level at: http://bit.ly/16Au8ol                   */
     

    /* Then convert the atmospheric pressure, SLP and temp to altitude    */
    /* Update this next line with the current SLP for better results      */
    float seaLevelPressure = SENSORS_PRESSURE_SEALEVELHPA; // should be ~1000
    Serial.print("Sea level pressure: "); 
    Serial.print(SENSORS_PRESSURE_SEALEVELHPA);
    Serial.println(" millibar/hPa");
    
    Serial.print("Altitude:    "); 
    Serial.print(bmp.getAltitude(seaLevelPressure)); 
    Serial.println(" m");
    Serial.println("");

    delay(1000);
}

[/codesyntax]

Output

Open the serial monitor and you should see something like this

Pressure: 98595 Pascals / 985 millibar (hPa)
Temperature: 23.24 C
Sea level pressure: 1013.25 millibar/hPa
Altitude: 230.92 m

Pressure: 98574 Pascals / 985 millibar (hPa)
Temperature: 23.26 C
Sea level pressure: 1013.25 millibar/hPa
Altitude: 230.58 m

Pressure: 98584 Pascals / 985 millibar (hPa)
Temperature: 23.24 C
Sea level pressure: 1013.25 millibar/hPa
Altitude: 230.07 m

Links