distance measure

#include <stdio.h>
#include <math.h>
#include "NUC100Series.h"
#include "MCU_init.h"
#include "SYS_init.h"
#include "LCD.h"
#define SECOND 10000000
#define MILLISECOND 10000
#define MICROSECOND 10


void System_Config(void);
void Delay_s(uint32_t count);

void Timer_Config(void);
void TMR2_Start(void);
void TMR2_Stop(void);

void Interrupt_Config(void);
void EINT1_IRQHandler(void);
void trigger(void);

void SPI3_Config(void);
void LCD_start(void);
void LCD_command(unsigned char temp);
void LCD_data(unsigned char temp);
void LCD_clear(void);
void LCD_SetAddress(uint8_t PageAddr, uint8_t ColumnAddr);
void GPIO_Config(void);
void HandleDelay(void);

uint8_t echo_flag;

long blink_delay, dist, trigger_delay, target;

int main(void)
{
    //System initialization------------------------------------------------------
    System_Config();
    Interrupt_Config();
    Timer_Config();
    GPIO_Config();
    SPI3_Config();
    LCD_start();
    LCD_clear();

    echo_flag = 0;


    while (1) {
        HandleDelay();
    }
}

void HandleDelay(void) {
    if (trigger_delay > 250) {
        trigger();
        trigger_delay = 0;
    }
    if (dist < 1000)
        target = 20000;
    else if (dist < 2500)
            target = 30000;
    else if (dist < 4000)
        target = 40000;
    else
        target = 50000;
    if (blink_delay > target){
        PC->DOUT ^= (1<<12);
        PB->DOUT ^= (1<<11);
        blink_delay = 0;
    }
    Delay_s(1000);
    trigger_delay++;
    blink_delay += 200;
}

//Time Counting and Interrupt Functions-------------------------------------------------------------
void display_dist(void) { //Calculates dist based off timer value, converts to char[] and prints on LCD
    uint8_t i;
    char string[6];
    uint32_t array[5];
    dist *= 17;
    dist /= 11;
    for (i = 0; i < 4; i++)
        array[i] = (dist / (uint32_t)pow(10,4-i)) % 10;
    for (i = 0; i < 4; i++)
        string[i] =  '0' + array[i];
    print_Line(1, string);
    print_Line(0, "dist(mm):");
    for (i = 0; i < 4; i++)
        string[i] = '0';
}

void trigger(void){ //Sends 10 microsecond pulse to sensor TRIG pin
    PB->DOUT ^= 1<<12;
    Delay_s(10);
    PB->DOUT ^= 1<<12;
}

void EINT1_IRQHandler(void){ //Interrupt based on sensor ECHO pin rising edge and falling edge
    if (!echo_flag)
        TMR2_Start();
    else {
        TMR2_Stop();
        display_dist();
    }
    echo_flag = !echo_flag;
    PB->ISRC |= (1ul << 15);    // set that interrupt ended
}

void TMR2_Start(void){  //Start the timer
    TIMER2->TCSR &= ~(0xFFul << 0);
    TIMER2->TCSR |= (0x9ul << 0); // Now, the timer frequency = 1MHz / (9 + 1) = 100 kHz
    TIMER2->TCMPR = 16777215; //set TCMPR to highest 24-bit value possible (because we don't want the timer to be limited)
    TIMER2->TCSR |= (1ul << 30); //Activate TMR2
}

void TMR2_Stop(void){ //Stop the timer
    TIMER2->TCSR &= ~(1ul << 30); //Deactivate TMR2
    dist = TIMER2->TDR;
    TIMER2->TCSR |= (1ul << 26); //Reset TMR2 prescale, count value, and bit 30
}

void Delay_s(uint32_t count){ //Basic delay function
    uint32_t n;
    for(n=0;n<count;n++);
}


// System and Module Configuration Functions---------------------------------------
void System_Config(void){
    SYS_UnlockReg(); // Unlock protected registers

    //Enable clock source: HXT 12MHz
    CLK->PWRCON |= (1ul << 0);
    while(!(CLK->CLKSTATUS & (1ul << 0)));

    //PLL configuration starts
    CLK->PLLCON &= ~(1ul<<19); //0: PLL input is HXT
    CLK->PLLCON &= ~(1ul<<16); //PLL in normal mode
    CLK->PLLCON &= (~(0x01FFul << 0));
    CLK->PLLCON |= 10; //Frequency is now = 12 / (10 + 2) = 1 MHz
    CLK->PLLCON &= ~(1ul<<18); //0: enable PLLOUT
    while(!(CLK->CLKSTATUS & (0x01ul << 2)));
    //PLL configuration ends

    //clock source selection
    CLK->CLKSEL0 &= (~(0x07ul << 0));
    CLK->CLKSEL0 |= (0x02ul << 0);
    //clock frequency division
    CLK->CLKDIV &= (~0x0Ful << 0);
    //enable clock of SPI3
    CLK->APBCLK |= 1ul << 15;

    SYS_LockReg(); // Lock protected registers
}

void SPI3_Config (void){
    SYS->GPD_MFP |= 1ul << 11; //1: PD11 is configured for alternative function
    SYS->GPD_MFP |= 1ul << 9; //1: PD9 is configured for alternative function
    SYS->GPD_MFP |= 1ul << 8; //1: PD8 is configured for alternative function

    SPI3->CNTRL &= ~(1ul << 23); //0: disable variable clock feature


    SPI3->CNTRL &= ~(1ul << 22); //0: disable two bits transfer mode
    SPI3->CNTRL &= ~(1ul << 18); //0: select Master mode
    SPI3->CNTRL &= ~(1ul << 17); //0: disable SPI interrupt
    SPI3->CNTRL |= 1ul << 11; //1: SPI clock idle high
    SPI3->CNTRL &= ~(1ul << 10); //0: MSB is sent echo_flag
    SPI3->CNTRL &= ~(3ul << 8); //00: one transmit/receive word will be executed in one data transfer

    SPI3->CNTRL &= ~(31ul << 3); //Transmit/Receive bit length
    SPI3->CNTRL |= 9ul << 3; //9: 9 bits transmitted/received per data transfer

    SPI3->CNTRL |= (1ul << 2); //1: Transmit at negative edge of SPI CLK
    SPI3->DIVIDER = 0; // SPI clock divider. SPI clock = HCLK / ((DIVIDER+1)*2). HCLK = 50 MHz
}

void Interrupt_Config(void) {
    //hook echo pin = GPIO-B15

    //GPIO Interrupt configuration.  is the interrupt source
    PB->PMD &= (~(0x03ul << 30));       // Input mode
    PB->IMD &= (~(1ul << 15));          // 0: edge level detection
    PB->IEN |= (1ul << 15);                 // enable falling edge trigger
    PB->IEN |= (1ul << (15+16));        // enable rising edge trigger as well

    //NVIC interrupt configuration for GPIO-B15 interrupt source
    NVIC->ISER[0] |= 1ul<<3;
    NVIC->IP[0] &= (~(3ul<<30));
}

void Timer_Config(void){
    CLK->CLKSEL1 &= ~(0x07ul << 16);
    CLK->CLKSEL1 |= (0x02ul << 16); //Use HCLK as TMR2 source
    CLK->APBCLK |= (0x01ul << 4);       //Enable TMR2 channel
    TIMER2->TCSR &= ~(0xFFul << 0);
    TIMER2->TCSR |= (0x9ul << 0); // Now, the timer frequency = 1MHz / (9 + 1) = 100 kHz
    TIMER2->TCSR &= ~(0x03ul << 27); //set TMR2 to One-shot mode
    TIMER2->TCMPR = 16777215; //set TCMPR to highest 24-bit value possible (we want to avoid timer limitations)
    TIMER2->TCSR |= (0x01ul << 16); //TDR enabled
    TIMER2->TCSR &= ~(0x01ul << 29); //Disable TMR2 interrupt
    TIMER2->TISR |= (0x01ul << 0); //Clear interrupt flag
    TIMER2->TCSR &= ~(1ul << 30); //Deactivate TMR2
    }

void GPIO_Config(void) {
    //Configuring buzzer and LED
    PC->PMD &= (~(0x03ul << 24));
    PC->PMD |= (0x01ul << 24);

    PB->PMD &= (~(0x03ul << 22));
    PB->PMD |= (0x01ul << 22);

    //Configure PB15 to send 10 microsecond pulse to trigger pin
    PB->PMD &= (~(0x03ul << 24));
    PB->PMD |= (0x01ul << 24);

}


// LCD Functions---------------------------------------------------------------------
void LCD_start(void) {
    LCD_command(0xE2); // Set system reset
    LCD_command(0xA1); // Set Frame rate 100 fps
    LCD_command(0xEB); // Set LCD bias ratio E8~EB for 6~9 (min~max)
    LCD_command(0x81); // Set V BIAS potentiometer
    LCD_command(0xA0); // Set V BIAS potentiometer: A0 ()
    LCD_command(0xC0);
    LCD_command(0xAF); // Set Display Enable
}

void LCD_command(unsigned char temp) {
    SPI3->SSR |= 1ul << 0;
    SPI3->TX[0] = temp;
    SPI3->CNTRL |= 1ul << 0;
    while(SPI3->CNTRL & (1ul << 0));
    SPI3->SSR &= ~(1ul << 0);
}

void LCD_data(unsigned char temp) {
    SPI3->SSR |= 1ul << 0;
    SPI3->TX[0] = 0x0100+temp;
    SPI3->CNTRL |= 1ul << 0;
    while(SPI3->CNTRL & (1ul << 0));
    SPI3->SSR &= ~(1ul << 0);
}

void LCD_clear(void) {
    int16_t i;
    LCD_SetAddress(0x0, 0x0);
    for (i = 0; i < 132 *8; i++)
        LCD_data(0x00);

}

void LCD_SetAddress(uint8_t PageAddr, uint8_t ColumnAddr) {
    LCD_command(0xB0 | PageAddr);
    LCD_command(0x10 | (ColumnAddr>>4)&0xF);
    LCD_command(0x00 | (ColumnAddr & 0xF));
}