PIC18F46K22 Interface with BMP280 sensor and SSD1306 OLED display

This tutorial shows how to interface PIC18F46K22 microcontroller with BMP280 barometric pressure and temperature sensor.
The PIC18F46K22 MCU reads temperature & pressure values from the BMP280 sensor and print them (respectively in °C and hPa) on SSD1306 OLED display (128×64 pixel).
MikroC PRO for PIC compiler is used in this project.

In this project the SSD1306 OLED is configured to work in I2C mode, make sure that your display is configured to work in I2C mode, some displays need jumper placing or some soldering.

To see how to interface PIC18F46K22 MCU with SSD1306 OLED display (I2C mode), visit this topic:
Interfacing PIC18F46K22 with SSD1306 OLED display | mikroC Projects

and to see how to interface PIC microcontroller with BMP280 sensor using mikroC PRO for PIC compiler, take a look at this project:
PIC MCU with BMP280 temperature and pressure sensor | mikroC Projects

Hardware Required:

PIC18F46K22 microcontroller —-> datasheet
SSD1306 OLED display
BMP280 sensor module (with built-in 3.3V regulator and level shifter) —-> BMP280 datasheet
5V source
Breadboard
Jumper wires

PIC18F46K22 with SSD1306 OLED and BMP280 sensor circuit:
The image below shows project circuit diagram.

Hint:
The BMP280 chip works with maximum voltage of 3.6V (supply voltage range is from 1.71 to 3.6V) which means we’ve to use a 3V3 voltage regulator to supply it from a 5V source.
Also, if we’re working with a 5V system (development board, microcontroller …) like the PIC18F46K22 microcontroller, we’ve to use a voltage level shifter (level converter) which converts the 3.3V (comes from the BMP280 chip) into 5V (goes to the PIC18F46K22) and vice versa. This level shifter is for the I2C bus lines (clock and data).
The BMP280 module shown in project circuit diagram has a built-in 3.3V regulator and level shifter.

All the grounded terminals are connected together.

The PIC18F46K22 microcontroller has 2 hardware I2C modules (MSSP1 and MSSP2 modules).
In this project I2C1 module is used with SDA1 on pin RC4 (#23) and SCL1 on pin RC3 (#18). The SDA1 pin of the MCU is connected to the SDA pin of the display and the SCL1 pin of the MCU is connected to the SCL pin of the display.
The reset pin of the display is connected to pin RD4 (#27) of the microcontroller.

The SSD1306 OLED display DC pin is connected to VDD which means I2C slave address of the device is 0x7A.

Generally, the BMP280 module has at least 4 pins because it can work in SPI mode or I2C mode. For the I2C mode we need 4 pins: VCC, GND, SCL and SDA, where:
GND (ground) is connected to circuit ground (0V)
VCC is the supply pin, it is connected to +5V
SCL is I2C bus serial clock line, connected to PIC18F46K22 SCL1 (RC3) pin
SDA is I2C bus serial data line, connected to PIC18F46K22 SDA1 (RC4) pin.

The SSD1306 OLED and the BMP280 sensor are connected to the same I2C bus (slave devices), SCL and SDA pins of the two devices are connected to SCL1 and SDA1 pins of the PIC18F46K22.
The I2C slave address of the SSD1306 OLED differs from the one of the BMP280 sensor, this difference allows the master device (PIC18F46K22) to talk to one of them (only one at a time).

In this project the PIC18F46K22 microcontroller runs with its internal oscillator @ 16 MHz, MCLR pin is configured as an input pin.

PIC18F46K22 with SSD1306 OLED and BMP280 sensor C code:
The following C code is for mikroC PRO for PIC compiler, it was tested with version 7.2.0.

To be able to compile the C code below with no error, a driver for the SSD1306 OLED display is required, its full name (with extension) is SSD1306OLED.c, download link is the one below:
SSD1306 OLED mikroC library

for more information about this driver, visit the following post:
SSD1306 OLED display library for mikroC compiler | mikroC Projects

Also, another library for the BMP280 sensor is required, its full name (with extension) is BMP280.c, download link is below:
BMP280 Library for mikroC compiler

after the download of the 2 library files, add both of them to mikroC project folder.

The BMP280 I2C address and the reset pin of the SSD1306 OLED display are defined in the C code as shown below:

// define BMP280 device I2C address: 0xEC or 0xEE (0xEE is library default address)
#define BMP280_I2C_ADDRESS  0xEC

// SSD1306 OLED reset pin definition (if available)
#define SSD1306_RST       RD4_bit
#define SSD1306_RST_DIR   TRISD4_bit

// define BMP280 device I2C address: 0xEC or 0xEE (0xEE is library default address)

#define BMP280_I2C_ADDRESS 0xEC

// SSD1306 OLED reset pin definition (if available)

#define SSD1306_RST RD4_bit

#define SSD1306_RST_DIR TRISD4_bit

The driver files of the SSD1306 OLED display and the BMP280 sensor are included in the code using the following 2 lines:

#include <SSD1306OLED.c>  // include SSD1306 OLED display driver source code
#include <BMP280.c>       // include BMP280 sensor driver source file

1 2	#include <SSD1306OLED.c> // include SSD1306 OLED display driver source code #include <BMP280.c> // include BMP280 sensor driver source file

Reading temperature and pressure values is done as shown below.
Note that the BMP280 library returns the temperature in hundredths °C which means we’ve to divide it by 100 and it returns the pressure in Pa, to get the pressure in hPa we’ve to divide it also by 100.

// Read temperature (in hundredths C) and pressure (in Pa)
//   values from the BMP280 sensor
BMP280_readTemperature(&temp);  // read temperature
BMP280_readPressure(&pres);     // read pressure

// Read temperature (in hundredths C) and pressure (in Pa)

// values from the BMP280 sensor

BMP280_readTemperature(&temp); // read temperature

BMP280_readPressure(&pres); // read pressure

Temperature and pressure values are displayed on the SSD1306 OLED screen.
If there is a problem with the BMP280 sensor (for example wrong device address) the screen will display Connection Error.

1 bar = 10000 Pa = 100 hPa. ( 1 hPa = 100 Pa)
Pa: Pascal
hPa: hectoPascal

Rest of code is described through comments.

Full mikroC code:

/**************************************************************************************

  Interfacing PIC18F46K22 microcontroller with SSD1306 OLED (128x64 Pixel)
    and BMP280 pressure & temperature sensor.
  C Code for mikroC PRO for PIC compiler.
  Internal oscillator used @ 16MHz
  Configuration words: CONFIG1H = 0x0028
                       CONFIG2L = 0x0018
                       CONFIG2H = 0x003C
                       CONFIG3H = 0x0037
                       CONFIG4L = 0x0081
                       CONFIG5L = 0x000F
                       CONFIG5H = 0x00C0
                       CONFIG6L = 0x000F
                       CONFIG6H = 0x00E0
                       CONFIG7L = 0x000F
                       CONFIG7H = 0x0040
  This is a free software with NO WARRANTY.
  http://simple-circuit.com/

***************************************************************************************/

// define BMP280 device I2C address: 0xEC or 0xEE (0xEE is library default address)
#define BMP280_I2C_ADDRESS  0xEC

// SSD1306 OLED reset pin definition (if available)
#define SSD1306_RST       RD4_bit
#define SSD1306_RST_DIR   TRISD4_bit

#include <SSD1306OLED.c>  // include SSD1306 OLED display driver source code
#include <BMP280.c>       // include BMP280 sensor driver source file


// main function
void main()
{
  OSCCON = 0x70;      // set internal oscillator to 16MHz
  ANSELC = 0;         // configure all PORTC pins as digital
  ANSELD = 0;         // configure all PORTD pins as digital
  I2C1_Init(400000);  // initialize I2C communication with clock frequency of 400kHz
  delay_ms(1000);     // wait a second
  
  // initialize the SSD1306 OLED with an I2C addr = 0x7A (default address)
  SSD1306_Begin(SSD1306_SWITCHCAPVCC, SSD1306_I2C_ADDRESS);
  SSD1306_ClearDisplay();      // clear the display buffer
  SSD1306_SetTextWrap(false);  // disable text wrap
  SSD1306_GotoXY(25, 0);
  SSD1306_Print("BMP280 SENSOR");
  SSD1306_Display();
     
  // initialize the BMP280 sensor according to the following settings:
  // BMP280_begin(mode, T_sampling, P_sampling, filter, standby_time)
  if(BMP280_begin(MODE_NORMAL, SAMPLING_X1, SAMPLING_X1, FILTER_OFF, STANDBY_0_5) == 0)
  {  // connection error or device address wrong!
     SSD1306_TextSize(2);          // text size = 2
     SSD1306_GotoXY(5, 17);
     SSD1306_Print("Connection");
     SSD1306_GotoXY(35, 37);
     SSD1306_Print("Error");
     SSD1306_Display();
     while(1);  // stay here
  }

  SSD1306_GotoXY(29, 11);
  SSD1306_Print("TEMPERATURE:");
  SSD1306_GotoXY(38, 40);
  SSD1306_Print("PRESSURE:");
  SSD1306_Display();
  SSD1306_TextSize(2);   // text size = 2

  while(1)
  {
    long temp;
    unsigned long pres;
    char buffer[9];
    
    // Read temperature (in hundredths C) and pressure (in Pa)
    //   values from the BMP280 sensor
    BMP280_readTemperature(&temp);  // read temperature
    BMP280_readPressure(&pres);     // read pressure

    // print data on the LCD
    // 1: print temperature
    if(temp < 0)
      sprinti(buffer, "-%02u.%02u C", (int)(abs(temp)/100), (int)(abs(temp) % 100) );
    else
      sprinti(buffer, " %02u.%02u C", (int)(temp/100), (int)(temp % 100) );
    SSD1306_GotoXY(11, 21);
    SSD1306_Print(buffer);
    // print degree symblos ( ° )
    SSD1306_Color = true;           // set screen color
    SSD1306_DrawCircle(89, 23, 2);  // draw circle
    
    // 2: print pressure
    sprinti(buffer, "%04u.%02u", (int)(pres/100), (int)(pres % 100));
    SSD1306_GotoXY(3, 50);
    SSD1306_Print(buffer);
    SSD1306_GotoXY(91, 50);
    SSD1306_Print("hPa");
    SSD1306_Display();

    delay_ms(1000);   // wait a second
  }

}

// end of code.

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/**************************************************************************************

Interfacing PIC18F46K22 microcontroller with SSD1306 OLED (128x64 Pixel)

and BMP280 pressure & temperature sensor.

C Code for mikroC PRO for PIC compiler.

Internal oscillator used @ 16MHz

Configuration words: CONFIG1H = 0x0028

CONFIG2L = 0x0018

CONFIG2H = 0x003C

CONFIG3H = 0x0037

CONFIG4L = 0x0081

CONFIG5L = 0x000F

CONFIG5H = 0x00C0

CONFIG6L = 0x000F

CONFIG6H = 0x00E0

CONFIG7L = 0x000F

CONFIG7H = 0x0040

This is a free software with NO WARRANTY.

http://simple-circuit.com/

***************************************************************************************/

// define BMP280 device I2C address: 0xEC or 0xEE (0xEE is library default address)

#define BMP280_I2C_ADDRESS 0xEC

// SSD1306 OLED reset pin definition (if available)

#define SSD1306_RST RD4_bit

#define SSD1306_RST_DIR TRISD4_bit

#include <SSD1306OLED.c> // include SSD1306 OLED display driver source code

#include <BMP280.c> // include BMP280 sensor driver source file

// main function

void main()

{

OSCCON = 0x70; // set internal oscillator to 16MHz

ANSELC = 0; // configure all PORTC pins as digital

ANSELD = 0; // configure all PORTD pins as digital

I2C1_Init(400000); // initialize I2C communication with clock frequency of 400kHz

delay_ms(1000); // wait a second

// initialize the SSD1306 OLED with an I2C addr = 0x7A (default address)

SSD1306_Begin(SSD1306_SWITCHCAPVCC, SSD1306_I2C_ADDRESS);

SSD1306_ClearDisplay(); // clear the display buffer

SSD1306_SetTextWrap(false); // disable text wrap

SSD1306_GotoXY(25, 0);

SSD1306_Print("BMP280 SENSOR");

SSD1306_Display();

// initialize the BMP280 sensor according to the following settings:

// BMP280_begin(mode, T_sampling, P_sampling, filter, standby_time)

if(BMP280_begin(MODE_NORMAL, SAMPLING_X1, SAMPLING_X1, FILTER_OFF, STANDBY_0_5) == 0)

{ // connection error or device address wrong!

SSD1306_TextSize(2); // text size = 2

SSD1306_GotoXY(5, 17);

SSD1306_Print("Connection");

SSD1306_GotoXY(35, 37);

SSD1306_Print("Error");

SSD1306_Display();

while(1); // stay here

}

SSD1306_GotoXY(29, 11);

SSD1306_Print("TEMPERATURE:");

SSD1306_GotoXY(38, 40);

SSD1306_Print("PRESSURE:");

SSD1306_Display();

SSD1306_TextSize(2); // text size = 2

while(1)

{

long temp;

unsigned long pres;

char buffer[9];

// Read temperature (in hundredths C) and pressure (in Pa)

// values from the BMP280 sensor

BMP280_readTemperature(&temp); // read temperature

BMP280_readPressure(&pres); // read pressure

// print data on the LCD

// 1: print temperature

if(temp < 0)

sprinti(buffer, "-%02u.%02u C", (int)(abs(temp)/100), (int)(abs(temp) % 100) );

else

sprinti(buffer, " %02u.%02u C", (int)(temp/100), (int)(temp % 100) );

SSD1306_GotoXY(11, 21);

SSD1306_Print(buffer);

// print degree symblos ( ° )

SSD1306_Color = true; // set screen color

SSD1306_DrawCircle(89, 23, 2); // draw circle

// 2: print pressure

sprinti(buffer, "%04u.%02u", (int)(pres/100), (int)(pres % 100));

SSD1306_GotoXY(3, 50);

SSD1306_Print(buffer);

SSD1306_GotoXY(91, 50);

SSD1306_Print("hPa");

SSD1306_Display();

delay_ms(1000); // wait a second

}

// end of code.

The following picture shows a protoboard circuit of the project:

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