PCA9685Module PWMCtrlServo Library

A C library designed for PIC Microcontrollers to interface with the PCA9685 16-channel, 12-bit PWM controller. This library is ideal for projects requiring precise control of multiple Servos via the I2C bus (maybe you can used for LED dimming).

Features

• 16-Channel Control: Individually manage up to 16 PWM outputs with a single I2C connection.
• 12-bit Resolution: Precise control with 4096 steps of PWM duty cycle.
• Servo Optimized: Simplified functions to set pulse widths specifically for standard analog and digital servos.
• Configurable Frequency: Supports PWM frequencies from 24Hz to 1526Hz.
• I2C Addressable: Easily handle multiple PCA9685 modules on the same bus using hardware address pins.

Hardware Connection

The PCA9685 requires an I2C interface (SDA/SCL) and an optional Output Enable (OE) pin.

PCA9685 Pin	Function	PIC18 Connection (Example)
VCC	Logic Power	3.3V - 5V
V+	Servo Power	5V - 6V (External Source)
SDA	I2C Data	RB0 / SDA Pin
SCL	I2C Clock	RB1 / SCL Pin
OE	Output Enable	GND (Always ON) or Digital Pin
GND	Ground	Common Ground

Usage Example

This example demonstrates how to initialize the module and set a servo to a specific position.

#include <xc.h>
#include "pca9685.h"

void main(void) {
    // 1. Initialize I2C and System
    SYSTEM_Initialize();
    I2C_Init();
    
    // 2. Initialize PCA9685 (Address 0x40 is default)
    PCA9685_Init(0x40);
    
    // 3. Set PWM Frequency to 50Hz (Standard for Servos)
    PCA9685_SetPWMFreq(50);
    
    while(1) {
        // Set Channel 0 to 1.5ms pulse (Center for most servos)
        PCA9685_SetServoPulse(0, 1500); 
        
        __delay_ms(1000);
        
        // Set Channel 0 to 2.0ms pulse
        PCA9685_SetServoPulse(0, 2000);
        
        __delay_ms(1000);
    }
}

Project Structure

• src/: Core library files (pca9685.c, pca9685.h).
• examples/: Project examples for MPLAB X.
• LICENSE: MIT License.
• CHANGELOG: History of updates and bug fixes.

Documentation & Tutorial

For a detailed implementation explanation and step-by-step guide, you can review the following examples:

• https://mrchunckuee.blogspot.com/2026/05/PCA9685-PWMCtrlServo-Library.html