Complete Video Course on PIC18F4550 Microcontroller

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Table Of Contents

1. Complete Video Course on PIC18F4550 Microcontroller
2. I2C in PIC microcontroller (Inter-Integrated Circuit of PIC18F4550 – Step-by-Step Guide
3. What is I²C Communication?
4. PIC18F4550 I²C Pins
   • 🔹 Step 1: Configuring I²C Master Mode
   • Step 2: Writing and Reading Data
   • Step 3: Circuit Diagram
   • Step 4: Testing
5. Real-World Applications
6. Learn More
7. Complete Video Course on PIC18F4550 Microcontroller
   • Software development tools & documents:
8. 💬Frequently Asked Questions (FAQ)

I2C in PIC microcontroller (Inter-Integrated Circuit of PIC18F4550 – Step-by-Step Guide

The I2C in PIC (I²C , Inter-Integrated Circuit of PIC18F4550) communication protocol is one of the most efficient ways to connect multiple peripherals using just two wires. The PIC18F4550 microcontroller includes a built-in MSSP (Master Synchronous Serial Port) module that supports both I²C and SPI communication.
In this guide, we’ll explore how to configure the I²C module, understand the role of SDA and SCL pins, and create a simple master-slave communication example.

What is I²C Communication?

I²C is a two-wire, serial communication protocol that allows multiple slave devices to communicate with one or more masters.

• SDA (Serial Data) – Data line for sending and receiving bits
• SCL (Serial Clock) – Synchronizes data transfer

Each device has a unique 7-bit or 10-bit address, making it ideal for connecting sensors, EEPROMs, real-time clocks, and more.

PIC18F4550 I²C Pins

The I²C module in the PIC18F4550 uses the MSSP peripheral.

• SCL → RC3 (pin 18)
• SDA → RC4 (pin 23)

You can configure the MSSP as Master or Slave depending on your application.

🔹 Step 1: Configuring I²C Master Mode

We’ll configure the I²C module to act as a Master to communicate with a slave device like an EEPROM (24C02).

Code Snippet (MPLAB X + XC8):

#include <xc.h>

#define _XTAL_FREQ 8000000

void I2C_Init(const unsigned long baud)
{
    SSPCON = 0b00101000;   // Enable MSSP in I2C Master mode
    SSPCON2 = 0x00;
    SSPADD = (_XTAL_FREQ / (4 * baud)) - 1; // Baud rate
    SSPSTAT = 0x00;
    TRISC3 = 1;  // SCL as input
    TRISC4 = 1;  // SDA as input
}

void I2C_Start(void)
{
    SEN = 1;
    while(SEN);
}

void I2C_Stop(void)
{
    PEN = 1;
    while(PEN);
}

void I2C_Write(unsigned char data)
{
    SSPBUF = data;
    while(BF);
    while(SSPSTATbits.R_nW);
}

#include <xc.h>

#define _XTAL_FREQ 8000000

void I2C_Init(const unsigned long baud)
{
    SSPCON = 0b00101000;   // Enable MSSP in I2C Master mode
    SSPCON2 = 0x00;
    SSPADD = (_XTAL_FREQ / (4 * baud)) - 1; // Baud rate
    SSPSTAT = 0x00;
    TRISC3 = 1;  // SCL as input
    TRISC4 = 1;  // SDA as input
}

void I2C_Start(void)
{
    SEN = 1;
    while(SEN);
}

void I2C_Stop(void)
{
    PEN = 1;
    while(PEN);
}

void I2C_Write(unsigned char data)
{
    SSPBUF = data;
    while(BF);
    while(SSPSTATbits.R_nW);
}

Step 2: Writing and Reading Data

You can now write bytes to an external EEPROM, RTC, or sensor using standard I²C write and read sequences.

Example:

I2C_Start();
I2C_Write(0xA0); // Slave address + Write bit
I2C_Write(0x00); // Memory address
I2C_Write(0x55); // Data
I2C_Stop();

I2C_Start();
I2C_Write(0xA0); // Slave address + Write bit
I2C_Write(0x00); // Memory address
I2C_Write(0x55); // Data
I2C_Stop();

Step 3: Circuit Diagram

Connect the SCL and SDA lines between PIC18F4550 and a 24C02 EEPROM module.

• SCL (RC3) → EEPROM SCL
• SDA (RC4) → EEPROM SDA
• Pull-up resistors (4.7kΩ) to VCC (5V) on both lines.

Step 4: Testing

You can verify communication using:

• Logic analyzer (to observe start, ACK, and stop conditions)
• Reading data back using the I²C_Read function

Real-World Applications

• Interfacing EEPROM, RTC (DS1307), Temperature sensors (LM75, BMP280)
• Multi-device communication with minimal wiring
• Smart sensor networks

Learn More

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Complete Video Course on PIC18F4550 Microcontroller

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Software development tools & documents:

• MPLAB X IDE
• MPLAB X, XC8 Compiler
• Microchip Technology, pic18f4550

Tag: I2C in PIC, Inter Integrated Circuit in PIC18F4550

💬Frequently Asked Questions (FAQ)