Summary of PIC18Fxxx DC Servomotor using PIC18F452 with Proteus Simulation
This project implements a PID-based closed-loop DC servomotor control system on a PIC18F452, featuring trapezoidal motion profiling, encoder feedback, RS232 command/tuning, EEPROM storage, and Proteus VSM simulation for development and testing.
Parts used in the PIC18F452 DC Servomotor Project:
- PIC18F452 Microcontroller
- DC Servomotor
- Motor Driver IC (PWM controlled)
- Incremental Encoder
- External I2C EEPROM (24C01)
- RS232 Interface (USART)
- Power Supply (24V motor, 5V logic)
- Discrete components (resistors, capacitors, switches)
Introduction
This project demonstrates a DC servomotor control system based on Microchip Application Note AN696, implemented using the PIC18F452 microcontroller.
It is a complete microcontroller project that combines PID-based motor control, motion profiling, and RS232 serial communication.
Designed for embedded systems learning, this project shows how real-time control algorithms work inside a practical electronics application.
Using Proteus simulation, the entire system can be tested virtually before moving to hardware.
It is ideal for engineers and students exploring motor control, firmware design, and industrial-style motion systems.PIC18F servo control is demonstrated in this project using the PIC18F452 microcontroller to implement closed-loop PID motor positioning with encoder feedback, PWM drive, and Proteus simulation for accurate motion control.
How the Project Works (Overview)
The PIC18F452 controls a DC servomotor using a closed-loop PID control algorithm.
Motor position and speed feedback are obtained through encoder pulses counted by hardware timers.
Based on a predefined motion profile, the firmware continuously calculates position error, applies PID compensation, and updates PWM duty cycle in real time.
Commands are sent over RS232, allowing motion segments, PID gains, and execution modes to be modified dynamically.
Block Diagram / Workflow Explanation
RS232 Interface receives motion commands and configuration parameters
PIC18F452 MCU processes commands and manages motion profiles
Trajectory Generator computes velocity and position references
Encoder Feedback updates actual motor position and velocity
PID Controller calculates correction based on position error
PWM Module (CCP1) drives the motor driver
DC Servomotor executes precise controlled movement
This loop runs continuously inside a Timer2 interrupt, ensuring deterministic real-time control.
Key Features
PID-based closed-loop DC servomotor control
Trapezoidal motion profile generation (acceleration, velocity, deceleration)
RS232 command-based motor control and tuning
External EEPROM storage for motion segments and PID gains
Encoder-based position and velocity feedback
PWM motor drive using CCP module
Multiple execution modes via DIP switches
Designed for Proteus simulation and hardware deployment
Components Used
PIC18F452 Microcontroller
DC Servomotor
Motor Driver IC (PWM controlled)
Incremental Encoder
External I²C EEPROM (24C01)
RS232 Interface (USART)
Power Supply (24V motor, 5V logic)
Discrete components (resistors, capacitors, switches)
Applications
Industrial motion control training systems
Robotics actuator control
CNC axis simulation and learning platforms
Mechatronics and automation projects
Embedded motor control education
Servo tuning and PID experimentation
Explanation of Code (High-Level)
The firmware is written in MPLAB C18 and structured around real-time control concepts:
Interrupt Service Routine (ISR)
Executes servo calculations at fixed intervals using Timer2.Trajectory Generator (
UpdTraj)
Produces trapezoidal velocity and position profiles.Position Update (
UpdPos)
Reads encoder pulses using Timer0 and Timer1.PID Controller (
CalcPID)
Computes PWM duty cycle using proportional, integral, and derivative gains.Command Parser (
DoCommand)
Interprets RS232 commands for motion segments, PID tuning, and execution control.EEPROM Interface
Stores and retrieves motion profile data and PID parameters via I²C.
Source Code
#define DIST 0 // Array index for segment distance
#define VEL 1 // Array index for segment vel. limit
#define ACCEL 2 // Array index for segment accel.
#define TIME 3 // Array index for segment delay time
#define INDEX PORTBbits.RB0 // Input for encoder index pulse
#define NLIM PORTBbits.RB1 // Input for negative limit switch
#define PLIM PORTBbits.RB2 // Input for positive limit switch
#define GPI PORTBbits.RB3 // General purpose input
#define MODE1 !PORTBbits.RB4 // DIP switch #1
#define MODE2 !PORTBbits.RB5 // DIP switch #2
#define MODE3 !PORTBbits.RB6 // DIP switch #3
#define MODE4 !PORTBbits.RB7 // DIP switch #4
#define SPULSE PORTCbits.RC5 // Software timing pulse output
#define ADRES ADRESH // Redefine for 10-bit A/D converterProteus Simulation
In Proteus VSM, the PIC18F452 executes the firmware while the DC servomotor responds to PWM signals in real time.
Encoder pulses feed back into Timer0 and Timer1, allowing accurate position tracking.
RS232 terminal input enables live tuning of PID gains and motion segments, making the simulation highly interactive and educational.
(FAQs)
Conclusion
This PIC18F452 DC servomotor project is a powerful example of real-time embedded motor control.
It combines PID algorithms, motion profiling, EEPROM management, and serial communication into one cohesive system.
Whether used in Proteus simulation or real hardware, it offers excellent learning value for anyone working in embedded systems and motor control.
- Can this project run fully in Proteus simulation?
Yes, the complete system is designed for Proteus VSM testing. - Which PIC microcontrollers are compatible?
PIC18Fxxx devices with PWM, timers, and USART support are suitable. - How is motor position feedback implemented?
Using encoder pulses counted by Timer0 and Timer1. - Can PID parameters be changed during runtime?
Yes, via RS232 commands and stored in EEPROM. - What motion profile is used?
Trapezoidal motion profile with acceleration, velocity limit, and deceleration. - What baud rate does RS232 use?
19200 baud at 20 MHz system clock. - Is this suitable for real hardware deployment?
Yes, the design closely matches industrial servo control principles. - Can this be modified for stepper motors?
The control logic would require changes, but the framework is reusable.
