#include <math.h> // Include for round() function 
// --- Configuration Constants --- 
const int pwmPin = 13; 
const int frequency = 5000;    
// PWM frequency in Hz 
const uint8_t resolution = 8;  // Use 8-bit resolution (0-255 duty cycle range) 
// *** New Configuration: Duty Cycle as Percentage *** 
const float fixedDutyCyclePercent = 75.0; // Desired fixed duty cycle (0.0 to 100.0) 
// --- Calculated Values --- 
// Calculate the maximum raw duty cycle value based on the resolution 
// (1 << N) is 2^N. Max value is 2^N - 1. 
const uint32_t maxDutyCycle = (1 << resolution) - 1; // For 8-bit, this is 255 
// --- Helper Function --- 
// Converts a percentage (0-100) to the raw duty cycle value for the configured resolution 
uint32_t percentageToDuty(float percentage) { 
// Clamp percentage to the valid range 0.0 to 100.0 
if (percentage < 0.0) { 
percentage = 0.0; 
} else if (percentage > 100.0) { 
percentage = 100.0; 
} 
// Calculate the raw duty cycle value 
// (percentage / 100.0) gives the fraction (0.0 to 1.0) 
// Multiply by the maximum possible duty cycle value for the chosen resolution 
// Use round() for the nearest integer value 
return (uint32_t)round((percentage / 100.0) * maxDutyCycle); 
} 
// ========================== SETUP ========================== 
void setup() { 
Serial.begin(115200); 
Serial.println("ESP32 Fixed PWM (Percentage Input) Example (Pin-Based API)"); 
// 1. Configure and attach the PWM pin using LEDC 
ledcAttach(pwmPin, frequency, resolution); 
Serial.printf("Attached PWM to GPIO %d\n", pwmPin); 
Serial.printf("Frequency: %d Hz, Resolution: %d bits (Max Duty Value: %u)\n", 
frequency, resolution, maxDutyCycle); 
// 2. Convert the desired percentage to the raw duty cycle value 
uint32_t calculatedDutyValue = percentageToDuty(fixedDutyCyclePercent); 
Serial.printf("Requested Duty Cycle: %.2f %%\n", fixedDutyCyclePercent); 
Serial.printf("Calculated Raw Duty Value: %u\n", calculatedDutyValue); 
// 3. Set the fixed PWM duty cycle using ledcWrite with the PIN number 
//    and the CALCULATED duty value 
ledcWrite(pwmPin, calculatedDutyValue); // Using pwmPin and calculated value 
Serial.printf("Set fixed duty cycle %u on pin %d\n", calculatedDutyValue, 
pwmPin); 
Serial.println("PWM signal is now active."); 
} 
// ========================== LOOP ========================== 
void loop() { 
// PWM is handled by hardware. Nothing needed here for fixed output. 
delay(1000); 
}