cs_reference_oscillator.c

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/*******************************************************************************
 * MSP432 Clock System - Reference Oscillator
 *
 * 描述：
 * 这是一个简单的代码示例，它从内部参考振荡器REFOCLK获取MCLK,并使用SysTick模块使LED闪烁。
 * P1.1（开关）发生中断，这将改变两种模式（32khz和128 khz）之间参考振荡器的频率。
 *
 *              MSP432P401
 *             ------------------
 *         /|\|                  |
 *          | |                  |
 *          --|RST         P1.0  |---> P1.0 LED
 *            |                  |
 *            |            P1.1  |<--Toggle Switch
 *            |                  |
 *            |                  |
 *
 ******************************************************************************/
/* DriverLib Includes */
#include <ti/devices/msp432p4xx/driverlib/driverlib.h>

/* Standard Includes */
#include <stdint.h>
#include <stdbool.h>

/* Statics */
static volatile bool is32khz;

int main(void)
{
    //停用看门狗
    MAP_WDT_A_holdTimer();
    is32khz = true;

    //配置引脚P1.0为输出,外接LED
    MAP_GPIO_setAsOutputPin(GPIO_PORT_P1, GPIO_PIN0);
    //配置引脚P1.1为输入,使能内部上拉;
    MAP_GPIO_clearInterruptFlag(GPIO_PORT_P1, GPIO_PIN1);
    MAP_GPIO_setAsInputPinWithPullUpResistor(GPIO_PORT_P1, GPIO_PIN1);

    //配置MCLK=REFO,  REFOCLK默认为32768
    MAP_CS_initClockSignal(CS_MCLK, CS_REFOCLK_SELECT, CS_CLOCK_DIVIDER_1);

    //时钟为32khz,可以工作在模式LF
    MAP_PCM_setPowerMode(PCM_LF_MODE);

    //配置SysTick计数值为16000.
    //在32khz下,LED取反的频率约为0.5s, 如果时钟为128K,则4倍速率
    MAP_SysTick_enableModule();
    MAP_SysTick_setPeriod(16000);
    MAP_SysTick_enableInterrupt();
    MAP_GPIO_enableInterrupt(GPIO_PORT_P1, GPIO_PIN1);
    MAP_Interrupt_enableInterrupt(INT_PORT1);

    //使能全局中断
    MAP_Interrupt_enableMaster();

    while (1)
    {
        MAP_PCM_gotoLPM0();
    }
}

/* SysTick ISR */
void SysTick_Handler(void)
{
    MAP_GPIO_toggleOutputOnPin(GPIO_PORT_P1, GPIO_PIN0);
}

/* Port 1 ISR */
void PORT1_IRQHandler(void)
{
    uint32_t status;

    status = MAP_GPIO_getEnabledInterruptStatus(GPIO_PORT_P1);
    MAP_GPIO_clearInterruptFlag(GPIO_PORT_P1, status);

    if(status & GPIO_PIN1)
    {

        if(is32khz)
            MAP_CS_setReferenceOscillatorFrequency(CS_REFO_128KHZ);
        else
            MAP_CS_setReferenceOscillatorFrequency(CS_REFO_32KHZ);

        is32khz = !is32khz;

    }

}