ADC in PIC microcontroller(PIC18F4550)

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Table Of Contents

1. Full Practical Course on PIC18F4550 Microcontroller
2. Configuring ADC in PIC Microcontroller (Analog to Digital Converter) Module of PIC18F4550
3. ADC in PIC (PIC18F4550)
   • Key Features:
   • Step 1: Understanding ADC Pins
   • Step 2: Register Configuration Overview
   • Step 3: Configuration Steps (with Code)
   • Step 4: Practical Demonstration
   • Step 5: Going Beyond – Build a Real Project
4. Ready to Master PIC18F4550 than just learning ADC in PIC microcontroller?
5. Full Practical Course on PIC18F4550 Microcontroller

Configuring ADC in PIC Microcontroller (Analog to Digital Converter) Module of PIC18F4550

Suppose you’ve ever wanted to measure analog signals like temperature, light intensity, or voltage using a PIC microcontroller? In that case, the ADC (Analog-to-Digital Converter) is your gateway to the real world of signal processing.

In this post, we’ll explore how to configure and use the ADC module of the PIC18F4550 with practical steps – exactly the way you’ll do it in real embedded systems projects.

By the end of this post, you’ll not only understand the ADC concept but also be able to read sensor data and display it using C code on MPLAB X IDE or Proteus simulation.

ADC in PIC (PIC18F4550)

PIC18F4550 has a 10-bit ADC (Analog to Digital Converter) which can convert analog voltages (0V to 5V) into a digital value between 0 and 1023.
This means each bit represents approximately 4.88mV (5V / 1024).

Key Features:

• 10-bit resolution
• Up to 13 analog input channels (AN0 to AN12)
• Selectable voltage reference (Vref+ / Vref−)
• Conversion speed control via ADC clock
• Result format: left or right justified

Step 1: Understanding ADC Pins

The ADC channels are multiplexed with PORTA and PORTE pins.

ADC in PIC microcontroller (PIC18F4550)

So, before configuring the ADC in PIC microcontroller (PIC18F4550), make sure the corresponding pins are set as analog inputs in the ADCON1 register.

Step 2: Register Configuration Overview

To make the ADC work, we need to configure a few important registers.

Step 3: Configuration Steps (with Code)

Let’s go step-by-step:

#include <xc.h>
#define _XTAL_FREQ 8000000  // 8 MHz oscillator

void ADC_Init()
{
    ADCON1 = 0x0E;     // AN0 = Analog, others Digital
    ADCON2 = 0x89;     // Right justified, 8TAD, Fosc/8
    ADCON0 = 0x01;     // Select channel AN0, ADC ON
}

unsigned int ADC_Read(unsigned char channel)
{
    ADCON0 &= 0xC5;            // Clear channel selection bits
    ADCON0 |= (channel << 3);  // Select ADC channel
    __delay_ms(2);             // Acquisition time
    GO_nDONE = 1;              // Start conversion
    while(GO_nDONE);           // Wait until conversion complete
    return ((ADRESH<<8)+ADRESL); // Return result
}

void main(void)
{
    unsigned int adc_value;
    ADC_Init();
    
    TRISD = 0x00; // PORTD as output (for display purpose)
    
    while(1)
    {
        adc_value = ADC_Read(0);   // Read from channel 0
        PORTD = adc_value >> 2;    // Simple output demo
        __delay_ms(100);
    }
}

#include <xc.h>
#define _XTAL_FREQ 8000000  // 8 MHz oscillator

void ADC_Init()
{
    ADCON1 = 0x0E;     // AN0 = Analog, others Digital
    ADCON2 = 0x89;     // Right justified, 8TAD, Fosc/8
    ADCON0 = 0x01;     // Select channel AN0, ADC ON
}

unsigned int ADC_Read(unsigned char channel)
{
    ADCON0 &= 0xC5;            // Clear channel selection bits
    ADCON0 |= (channel << 3);  // Select ADC channel
    __delay_ms(2);             // Acquisition time
    GO_nDONE = 1;              // Start conversion
    while(GO_nDONE);           // Wait until conversion complete
    return ((ADRESH<<8)+ADRESL); // Return result
}

void main(void)
{
    unsigned int adc_value;
    ADC_Init();
    
    TRISD = 0x00; // PORTD as output (for display purpose)
    
    while(1)
    {
        adc_value = ADC_Read(0);   // Read from channel 0
        PORTD = adc_value >> 2;    // Simple output demo
        __delay_ms(100);
    }
}

Explanation:

• ADCON1 configures the pin type (analog/digital).
• ADCON2 sets the timing and justification.
• ADCON0 enables the ADC and selects the channel.
• GO_nDONE starts and monitors conversion.
• The result is fetched from ADRESH and ADRESL.

Step 4: Practical Demonstration

If you’re using:

• Proteus Simulation → Connect a variable resistor (potentiometer) to RA0.
• Hardware Board → Connect a sensor (like LM35 temperature sensor) to AN0 pin.

Run the program and observe how the PORTD LEDs or your LCD respond to varying input voltages.

✅ Tip: Add a 10nF–100nF capacitor from the analog input pin to ground and ensure proper grounding.

This hands-on test shows how the PIC18F4550 converts analog signals into meaningful digital data — a skill every embedded engineer must master.

Step 5: Going Beyond – Build a Real Project

Now that you’ve configured the ADC in PIC microcontroller (PIC18F4550) successfully, you can expand this into:

• Temperature Monitor System using LM35
• Light Intensity Meter using LDR
• Battery Voltage Indicator

Each of these projects is an exciting step toward real-world embedded design.

Ready to Master PIC18F4550 than just learning ADC in PIC microcontroller?

If you enjoyed this tutorial and want to learn the complete practical side of PIC18F4550, including:

• Timers, Interrupts, and UART Communication
• PWM for Motor Control
• USB Interface & Sensors Integration
• Real-world Project Building

👉 Then don’t miss our Premium Course: “Mastering PIC18F4550 Microcontroller”
🎓 A complete hands-on training designed for students, hobbyists, and engineers.

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Product: PIC18F4550

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