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This commit is contained in:
sherlock 2025-10-30 09:22:28 +05:30
parent a2d3f71108
commit 5c427867cd
2 changed files with 67 additions and 95 deletions
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46
ES/Lab/Lab11/PWM.c
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@ -1,57 +1,77 @@
#include "LPC17xx.h"
unsigned long int duty_cycle = 0;
int direction = 1;
int step = 50;
// Global variables for PWM control
unsigned long int duty_cycle = 0; // Current duty cycle value (0-3000)
int direction = 1; // Direction of duty cycle change: 1=increasing, 0=decreasing
int step = 50; // Amount to change duty cycle per interrupt
// PWM1 Interrupt Service Routine
// Called when PWM match register 0 triggers an interrupt
void PWM1_IRQHandler(void)
{
// Check if interrupt flag for PWM match channel 0 is set
if (LPC_PWM1->IR & (1 << 0))
{
// Ramp up the duty cycle if direction is 1
if (direction == 1)
{
duty_cycle += step;
// Check if we've reached maximum duty cycle
if (duty_cycle >= 3000)
{
duty_cycle = 3000;
direction = 0;
direction = 0; // Change direction to decreasing
}
}
// Ramp down the duty cycle if direction is 0
else
{
duty_cycle -= step;
// Check if we've reached minimum duty cycle
if (duty_cycle <= 0)
{
duty_cycle = 0;
direction = 1;
direction = 1; // Change direction to increasing
}
}
// Update PWM match register 4 with new duty cycle
LPC_PWM1->MR4 = duty_cycle;
// Latch the new match value
LPC_PWM1->LER = (1 << 4);
// Clear the interrupt flag for channel 0
LPC_PWM1->IR = (1 << 0);
}
}
int main(void)
{
// Configure P2.5 as PWM1[4] output
// PINSEL3 bits 15:14 = 10 for PWM1[4] function
LPC_PINCON->PINSEL3 |= (2 << 14);
LPC_PWM1->TCR = (1 << 1);
LPC_PWM1->CTCR = 0;
LPC_PWM1->PR = 0;
// Reset and configure PWM1 counter and prescaler
LPC_PWM1->TCR = (1 << 1); // Reset PWM counter
LPC_PWM1->CTCR = 0; // Timer mode (counter increments on PCLK)
LPC_PWM1->PR = 0; // Prescaler = 0 (no prescaling)
LPC_PWM1->MR0 = 3000;
LPC_PWM1->MR4 = duty_cycle;
// Set PWM cycle period and initial duty cycle
LPC_PWM1->MR0 = 3000; // PWM period (match register 0)
LPC_PWM1->MR4 = duty_cycle; // Initial duty cycle (match register 4)
LPC_PWM1->MCR = (1 << 1) | (1 << 0);
LPC_PWM1->PCR = (1 << 12);
// Configure PWM interrupts and enable output
LPC_PWM1->MCR = (1 << 1) | (1 << 0); // Reset on MR0 and interrupt on MR0
LPC_PWM1->PCR = (1 << 12); // Enable PWM4 output
// Latch the match register values
LPC_PWM1->LER = (1 << 0) | (1 << 4);
// Enable PWM1 interrupt in NVIC
NVIC_EnableIRQ(PWM1_IRQn);
LPC_PWM1->TCR = (1 << 0) | (1 << 3);
// Start PWM counter and enable PWM mode
LPC_PWM1->TCR = (1 << 0) | (1 << 3); // Counter enable and PWM enable
// Infinite loop - everything is handled by interrupts
while (1);
}