问将ATSAM3x8e端口配置为输出

EN

#include "sam.h"

uint32_t right_tick = 0;
uint32_t left_tick = 0;
uint32_t LED_status = 1;


void InitializeSystemTimer(void)
{
    const uint32_t tickcount = 1000000;
    // set value countdown restarts to
    SysTick->LOAD = tickcount;
    // set interrupt priority
    NVIC_SetPriority(SysTick_IRQn, 3);
    // restart timer
    SysTick->VAL = 0;
    // set system tick counter ClockSource/8, creates system tick exception when hits 0, enable system tick count,
    SysTick->CTRL = SysTick_CTRL_TICKINT_Msk|SysTick_CTRL_ENABLE_Msk;
}

void InitializeIOPorts(void)
{
    // enable Peripheral Clock on Port A
    PMC->PMC_PCER0 = ID_PIOA;
    
    // configure output pins
    
    // claim Port A control of pin 0, 1, 2
    PIOA->PIO_PER = PIO_PER_P0|PIO_PER_P1|PIO_PER_P2;
    // enable Port A output on pins
    PIOA->PIO_WPMR = PIO_WPMR_WPKEY_Msk;
    // set Port A pin 0, 1, 2 to output
    PIOA->PIO_PER = PIO_PER_P0|PIO_PER_P1|PIO_PER_P2;
    // set Port A pin 0, 1, 2 to be accessed directly by setting Output Write Enable Register
    PIOA->PIO_OWER = PIO_PER_P0|PIO_PER_P1|PIO_PER_P2;
    // set Port A pin 0, 1, 2 to high
    PIOA->PIO_ODSR = PIO_PER_P0|PIO_PER_P1|PIO_PER_P2;

    // configure input pins 
    
    // claim Port A control of pin 3, 4
    PIOA->PIO_PER = PIO_PER_P3|PIO_PER_P4;
    // set pull up resistors on pin 3, 4
    PIOA->PIO_PUER = PIO_PER_P3|PIO_PER_P4;
    // set interrupt on pin 3, 4
    PIOA->PIO_IER = PIO_PER_P3|PIO_PER_P4;
    // enable input change interrupt on Pin 3, 4 by setting mask
    PIOA->PIO_IMR = PIO_PER_P3|PIO_PER_P4;
    
    // set priority and enable interrupt for port A
    NVIC_SetPriority(PIOA_IRQn, 3);
    NVIC_EnableIRQ(PIOA_IRQn);
    
}

void InitializeUart(void)
{
    PMC->PMC_PCER0 = ID_UART;
    // baud rate is 84Mhz/(16*45)
    UART->UART_BRGR = uint32_t(45);
    UART->UART_CR = UART_CR_TXEN|UART_CR_RXEN;
    
    NVIC_SetPriority(UART_IRQn,2);
    NVIC_EnableIRQ(UART_IRQn);
}


void SysTick_Handler(void)
{
    if (LED_status == 0)
    {
        PIOA->PIO_SODR = PIO_PER_P0;
        LED_status = 1;
    }
    else
    {
        PIOA->PIO_CODR = PIO_PER_P0;
        LED_status = 0;
    }
    
}

void PIOA_Handler(void)
{
    uint32_t PORTA_interrupt_status = 0;
    PORTA_interrupt_status = PIOA->PIO_ISR;
    
    if ((PORTA_interrupt_status&PIO_PER_P3) == 1)
    {
        left_tick = left_tick+1;  
    }
    if ((PORTA_interrupt_status&PIO_PER_P4) == 1)
    {
        right_tick = right_tick + 1;
    }
}


void UART_Handler(void)
{
    
}


int main(void)
{
    /* Initialize the SAM system */
    SystemInit();
    InitializeSystemTimer();
    InitializeIOPorts();

    /* Replace with your application code */
    while (1) 
    {
    }
}