Brute Force Techniques I

#include <LPC17xx.H>

#define SHADOW_COPY 0x000000FF

void PWM_Init(void);
void PWM1_IRQHandler(void);

unsigned long int i;
unsigned char flag;

int main(void)
{
	PWM_Init();
	while (1)
		;
}

void PWM_Init(void)
{
	LPC_SC->PCONP = (1 << 6);		      // PWM1 is powered
	LPC_PINCON->PINSEL7 = 0x000C0000; // PWM1.2 is selected for the pin P3.25

	LPC_PWM1->PR = 0x00000000;	 // Count frequency : Fpclk
	LPC_PWM1->PCR = 0x00000400;	 // select PWM2 single edge
	LPC_PWM1->MCR = 0x00000003;	 // Reset and interrupt on PWMMR0
	LPC_PWM1->MR0 = 30000;		   // setup match register 0 count
	LPC_PWM1->MR2 = 0x00000100;	 // setup match register MR1
	LPC_PWM1->LER = SHADOW_COPY; // enable shadow copy register
	LPC_PWM1->TCR = 0x00000002;	 // RESET COUNTER AND PRESCALER
	LPC_PWM1->TCR = 0x00000009;	 // enable PWM and counter

	NVIC_EnableIRQ(PWM1_IRQn);
}

void PWM1_IRQHandler(void)
{
	LPC_PWM1->IR = 0xFF; // clear the interrupts

	if (flag == 0x00)
	{
		LPC_PWM1->MR2 += 100;
		LPC_PWM1->LER = SHADOW_COPY;

		if (LPC_PWM1->MR2 >= 27000) // Is Duty Cycle 90% ??
		{
			flag = 0xFF;
			LPC_PWM1->LER = SHADOW_COPY;
		}
	}
	else if (flag == 0xFF)
	{
		LPC_PWM1->MR2 -= 100;
		LPC_PWM1->LER = SHADOW_COPY;

		if (LPC_PWM1->MR2 <= 0x300) // Is Duty Cycle 1% ??
		{
			flag = 0x00;
			LPC_PWM1->LER = SHADOW_COPY;
		}
	}
}