[参考译文] MSP430FR5994：需要帮助以使用 UART 验证 C 代码、从而实现 MSP430FR5994

#include <msp430.h>
#include <stdint.h>

void Software_Trim();            // Software Trim to get the best DCOFTRIM value
#define MCLK_FREQ_MHZ 8                     // MCLK = 8MHz

// Déclarations des fonctions

void initUART(void);
void initPort(void);
void sendBuffer(void);

int main(void)
{
// Stop watchdog timer
    WDTCTL = WDTPW + WDTHOLD;

// Initialisation des périphériques
    initPort();
    PM5CTL0 &= ~LOCKLPM5; // Disable the GPIO power-on default high-impedance mode
                          // to activate 1previously configured port settings

    __bis_SR_register(SCG0);                 // disable FLL
    CSCTL3 |= SELREF__REFOCLK;               // Set REFO as FLL reference source
    CSCTL1 = DCOFTRIMEN_1 | DCOFTRIM0 | DCOFTRIM1 | DCORSEL_3; // DCOFTRIM=3, DCO Range = 8MHz
    CSCTL2 = FLLD_0 + 243;                  // DCODIV = 8MHz
    __delay_cycles(3);
    __bic_SR_register(SCG0);                // enable FLL
    Software_Trim();             // Software Trim to get the best DCOFTRIM value

    CSCTL4 = SELMS__DCOCLKDIV | SELA__REFOCLK; // set default REFO(~32768Hz) as ACLK source, ACLK = 32768Hz
                                               // default DCODIV as MCLK and SMCLK source
    initUART();

    while (1)
    {
// Send a predefined buffer via UART
        sendBuffer();



        P1OUT ^= BIT0; // Toggle LED to indicate sending data
        __delay_cycles(1000000); // Add a delay to avoid too fast a loop
    }

}
// Initialisation de l'horloge
void Software_Trim()
{
    unsigned int oldDcoTap = 0xffff;
    unsigned int newDcoTap = 0xffff;
    unsigned int newDcoDelta = 0xffff;
    unsigned int bestDcoDelta = 0xffff;
    unsigned int csCtl0Copy = 0;
    unsigned int csCtl1Copy = 0;
    unsigned int csCtl0Read = 0;
    unsigned int csCtl1Read = 0;
    unsigned int dcoFreqTrim = 3;
    unsigned char endLoop = 0;

    do
    {
        CSCTL0 = 0x100;                         // DCO Tap = 256
        do
        {
            CSCTL7 &= ~DCOFFG;                  // Clear DCO fault flag
        }
        while (CSCTL7 & DCOFFG);               // Test DCO fault flag

        __delay_cycles((unsigned int) 3000 * MCLK_FREQ_MHZ); // Wait FLL lock status (FLLUNLOCK) to be stable
                                                             // Suggest to wait 24 cycles of divided FLL reference clock
        while ((CSCTL7 & (FLLUNLOCK0 | FLLUNLOCK1)) && ((CSCTL7 & DCOFFG) == 0))
            ;

        csCtl0Read = CSCTL0;                   // Read CSCTL0
        csCtl1Read = CSCTL1;                   // Read CSCTL1

        oldDcoTap = newDcoTap;               // Record DCOTAP value of last time
        newDcoTap = csCtl0Read & 0x01ff;       // Get DCOTAP value of this time
        dcoFreqTrim = (csCtl1Read & 0x0070) >> 4;       // Get DCOFTRIM value

        if (newDcoTap < 256)                    // DCOTAP < 256
        {
            newDcoDelta = 256 - newDcoTap; // Delta value between DCPTAP and 256
            if ((oldDcoTap != 0xffff) && (oldDcoTap >= 256)) // DCOTAP cross 256
                endLoop = 1;                   // Stop while loop
            else
            {
                dcoFreqTrim--;
                CSCTL1 = (csCtl1Read & (~DCOFTRIM)) | (dcoFreqTrim << 4);
            }
        }
        else                                   // DCOTAP >= 256
        {
            newDcoDelta = newDcoTap - 256; // Delta value between DCPTAP and 256
            if (oldDcoTap < 256)                // DCOTAP cross 256
                endLoop = 1;                   // Stop while loop
            else
            {
                dcoFreqTrim++;
                CSCTL1 = (csCtl1Read & (~DCOFTRIM)) | (dcoFreqTrim << 4);
            }
        }

        if (newDcoDelta < bestDcoDelta)         // Record DCOTAP closest to 256
        {
            csCtl0Copy = csCtl0Read;
            csCtl1Copy = csCtl1Read;
            bestDcoDelta = newDcoDelta;
        }

    }
    while (endLoop == 0);                      // Poll until endLoop == 1

    CSCTL0 = csCtl0Copy;                       // Reload locked DCOTAP
    CSCTL1 = csCtl1Copy;                       // Reload locked DCOFTRIM
    while (CSCTL7 & (FLLUNLOCK0 | FLLUNLOCK1))
        ; // Poll until FLL is locked
}

// Initialisation de l'UART
void initUART(void)
{
    // Configure UART pins
    P1SEL0 |= BIT6 | BIT7;                  // set 2-UART pin as second function

    UCA0CTLW0 = UCSWRST; // Mise à la réinitialisation du module UART
    UCA0CTLW0 |= UCSSEL__SMCLK; // Sélection de SMCLK comme source d'horloge UART
    UCA0BRW = 52; // Configuration du débit en bauds à 9600 bauds
    UCA0MCTLW = UCOS16 | UCBRF_1 | 0x49; // Configuration des paramètres de modulation
    UCA0CTLW0 &= ~UCSWRST; // Sortie de la réinitialisation
    UCA0IE |= UCRXIE; // Activation des interruptions de réception UART
}

// Initialisation des ports GPIO
void initPort(void)
{
    P1OUT = 0x00;
    P1DIR = 0xFF;
    P1OUT |= BIT0;

    P2OUT = 0x00;
    P2DIR = 0xFF;

    PAOUT = 0x00;
    PADIR = 0xFF;

    PJOUT = 0x00;
    PJDIR = 0xFF;

    P2SEL0 &= ~(BIT0 | BIT1);
    P2SEL1 |= (BIT0 | BIT1);
}

// Function to send a predefined buffer via UART
void sendBuffer(void)
{
// Data buffer to send
    uint8_t buffer[] = { 0x01, 0x02, 0x03, 0x04, 0x05 };

// Send buffer via UART
    int i;

    for (i = 0; i < (sizeof(buffer)); i++)
    {
// Wait until transmission register is ready
        while (!(UCA0IFG & UCTXIFG))
            ;

// Send buffer element
        UCA0TXBUF = buffer[i];

// Wait until transmission is complete
        while (UCA0STATW & UCBUSY)
        ;
    }
}