#include <LPC17xx.h>

unsigned long pwm_value = 0;

void PWM_Init(void){
        LPC_PINCON->PINSEL3 |= 0x02 << 8;
        LPC_SC->PCONP |= 1 << 6;
        LPC_PWM1->PR = 0;
        LPC_PWM1->CTCR = 0;
        LPC_PWM1->MR0 = 1000;
        LPC_PWM1->MR2 = 500;
        LPC_PWM1->LER = 0x05;
        LPC_PWM1->PCR = 1 << 10;
        LPC_PWM1->TCR = 0x09;
        NVIC_EnableIRQ(PWM1_IRQn);
}

void Keyboard_Init(void){
        LPC_PINCON->PINSEL0 &= ~(0x03 << 0);
        LPC_PINCON->PINSEL0 &= ~(0x03 << 2);
        LPC_PINCON->PINSEL0 &= ~(0x03 << 4);
        LPC_PINCON->PINSEL0 &= ~(0x03 << 6);

        LPC_GPIO0->FIODIR &= ~(0x0F << 0);
}

void Delay(unsigned long count){
        unsigned long i;
        for(i = 0; i < count; i++);
}

unsigned char Read_Keyboard(void){
        unsigned char key = 0xFF;

        if(!(LPC_GPIO0->FIOPIN & (1 << 0))){
                Delay(500000);
                if(!(LPC_GPIO0->FIOPIN & (1 << 0))){
                        key = 0;
                        while(!(LPC_GPIO0->FIOPIN & (1 << 0)));
                        Delay(500000);
                }
        }
        else if(!(LPC_GPIO0->FIOPIN & (1 << 1))){
                Delay(500000);
                if(!(LPC_GPIO0->FIOPIN & (1 << 1))){
                        key = 1;
                        while(!(LPC_GPIO0->FIOPIN & (1 << 1)));
                        Delay(500000);
                }
        }
        else if(!(LPC_GPIO0->FIOPIN & (1 << 2))){
                Delay(500000);
                if(!(LPC_GPIO0->FIOPIN & (1 << 2))){
                        key = 2;
                        while(!(LPC_GPIO0->FIOPIN & (1 << 2)));
                        Delay(500000);
                }
        }
        else if(!(LPC_GPIO0->FIOPIN & (1 << 3))){
                Delay(500000);
                if(!(LPC_GPIO0->FIOPIN & (1 << 3))){
                        key = 3;
                        while(!(LPC_GPIO0->FIOPIN & (1 << 3)));
                        Delay(500000);
                }
        }

        return key;
}

int main(void){
        unsigned char key;

        PWM_Init();
        Keyboard_Init();

        while(1){
                key = Read_Keyboard();

                switch(key){
                        case 0:
                                pwm_value = 100;
                                LPC_PWM1->MR2 = pwm_value;
                                break;
                        case 1:
                                pwm_value = 250;
                                LPC_PWM1->MR2 = pwm_value;
                                break;
                        case 2:
                                pwm_value = 500;
                                LPC_PWM1->MR2 = pwm_value;
                                break;
                        case 3:
                                pwm_value = 750;
                                LPC_PWM1->MR2 = pwm_value;
                                break;
                        default:
                                break;
                }

                LPC_PWM1->LER |= 0x04;
        }

        return 0;
}

void PWM1_IRQHandler(void){
        LPC_PWM1->IR |= 0x01;
}