CCS/MSP430FR2111: MSP Low-Power Microcontroller Forum

/******************************************************************************
 * The following code shows how I am setting up the eCOMP module.
 * The main clock is running at 1 MHz.
 *
 * The comment header for the subroutine Init_eCOMP to see how the eCOMP module
 * is configured.
 *
 * I run the main loop in one of two ways.  When the registers configuration of
 * P1SEL0, P1SEL1, P2SEL0, and P2SEL1 are commented out, the while loop check
 * the front panel switch (FPS) to see if it is active.  If it is active, three
 * different LEDs are turned on.  If the FPS is inactive, all LEDs are turned
 * off.
 *
 * When the P1.0 is configured to drive the eCOMP (the registers configuration of
 * P1SEL0, P1SEL1, P2SEL0, and P2SEL1 are not commented out), the while loop
 * always reads P1.0 as low.  Which is okay, as the P1.0 signal is routed to the
 * positive input of the comparator.  The output of the comparator is
 * routed to P2.0.  P2.0 should output a low signal.  Out of six boards, one
 * works correctly and the other five to not.
 *
 * I understand that there is likely a board problem, but the only reason for
 * the P2.0 output to be high is when P1.0 is greater than 2.475 volts.  Which
 * is not the case.  The input signal P1.0 is low as can be verified by checking
 * the signal on pin 2.
 *****************************************************************************/
#include <msp430.h>

#define MCLK_FREQ_MHZ 1         // Set MCLK here (1 MHz)

// Forward function declarations
void Init_CS(void);
void Init_eCOMP(void);
void Software_Trim(void);

//*****************************************************************************
//************************  FRAM persistent variables  ************************
//*****************************************************************************
// FRAM persistent variables do not get initialized by the C startup routine,
// but rather the debug tool chain initializes them for the first time as the
// application code is loaded onto the target.  These variables are persistent
// across power cycles.
#pragma PERSISTENT(FAILSAFE_count)
unsigned int FAILSAFE_count = 0;

int main(void)
{
    unsigned int FS_temp = 0xE;
    WDTCTL = WDTPW | WDTHOLD;           // Stop watchdog timer

    Init_CS();                          // Set system clock
    Init_eCOMP();               // Set up comparator

    P1DIR = 0xD8;               // Set direction of pins
    P2DIR = 0xFF;

    P1OUT = 0xD0;               // On-board LED on, DTR on, high = MPS off
    P2OUT = 0x02;               // FPS LED high = off

    // Configure Comparator input & output
    P1SEL0 |= BIT0;       // Select 3rd module function
    P1SEL1 |= BIT0;       // eCOMP input function on P1.0/C0
    P2DIR |= BIT0;
    P2SEL0 &= BIT0;       // Select 2nd module function
    P2SEL1 |= BIT0;       // Select CPOUT function on P2.0/COUT

    PM5CTL0 &= ~LOCKLPM5;



    while(1)                       // Capture loop
    {
        if(P1IN & BIT0)
        {
            P1OUT |= BIT6;      // On-board LED on
            P1OUT &= ~BIT7;     // MPS LED on
            P2OUT &= ~BIT1;     // FPS LED on
        }
        else
        {
            P1OUT &= ~BIT6;     // On-board LED off
            P1OUT |= BIT7;     // MPS LED off
            P2OUT |= BIT1;     // FPS LED off
        }
    }

}

//******************************************************************************
//  Init_CS - Initialize configuration of clock systems
//******************************************************************************
//  Configure MCLK for 1MHz.
//  FLL reference clock is REFO.
//  ACLK = default REFO ~32768Hz.
//  SMCLK = MCLK = 1MHz.
//  Use DCO software trim to lock FLL. If FLL is locked and
//  DCO tap is closest to 256, the DCOFTRIM value is the best one.
//******************************************************************************
void Init_CS(void)
{
    __bis_SR_register(SCG0);            // Disable FLL
    CSCTL3 = SELREF__REFOCLK;           // Set REFO as FLL reference source
    CSCTL1 = DCOFTRIMEN_1 | DCOFTRIM0 | DCOFTRIM1 | DCORSEL_0;  // DCOFTRIM=3,
                                                                //DCO Range=1MHz
    CSCTL2 = FLLD_0 + 30;               // DCODIV = 1MHz
    __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
}

//******************************************************************************
//  Init_eCOMP - Initialize configuration of comparator
//******************************************************************************
//  The eCom module is set up so that the Front panel switch on port pin P1.0 is
//  connected to the positive input of the comparator.  The negative input of the
//  comparator is connected to the DAC output.  The DAC output is controlled by
//  two buffers.  Buffer 1 is set for 3/4 of VCC so that the output of the
//  comparator goes positive only after the positive input is above 3/4 of VCC.
//  When the comparator output goes high, the DAC output switches to buffer 2.
//  Buffer 2 is setup for 1/4 of VCC.  Now the positive input must go below 1/4
//  of VCC for the comparator output to switch back to a low level.  This provides
//  hysteresis for the switch input.
//
//  The output of the comparator is then filtered to further prevent
//  oscillations in the output due to switch bounce.
//
//  The output of the comparator is then connected to both the port pin P2.0 and
//  the capture/compare block 1.  The capture 1 register is set up to capture both
//  the rising and falling edges of the comparator output.  The difference
//  between the rising and falling edges determines how long the switch is pressed.
//
//  When the rising edge is detected, it start the compare block 0.  The
//  compare block 0 is set to trigger an interrupt 6 seconds after the rising
//  edge.  If the falling edge occurs before the 6 second compare interrupt
//  occurs, then the button press is processed normally.  If the 6 second compare
//  interrupt occurs before the falling edge, then the state changes to the
//  FAILSAFE mode.
//******************************************************************************
void Init_eCOMP(void)
{
    // Configure reference
      PMMCTL0_H = PMMPW_H;                      // Unlock the PMM registers
      PMMCTL2 |= INTREFEN;                      // Enable internal reference
      __delay_cycles(400);                      // Delay for reference settling

      // Setup comparator
      CPCTL0 |= CPPSEL_0;         // Select C0 as input for V+ terminal
      CPCTL0 |= CPNSEL_6;         // Select DAC as input for V- terminal
      CPCTL0 |= CPPEN | CPNEN;    // Enable both eCOMP inputs
      CPDACCTL = CPDACEN;         // Select VCC as reference and enable DAC
      CPDACDATA = 0x1030;         // CPDACBUF1=VCC *3/4   CPDACBUF2=VCC *1/4
      CPCTL1 |= CPFLT | CPFLTDLY_3 | CPMSEL | CPEN;
//                |         |          |        |--- Turn on eCOMP
//                |         |          |------------ Low power low speed mode
//                |         |----------------------- Analog filter delay 3.6 ms
//                |--------------------------------- Enable analog filter

    // Setup capture/compare block 0 for compare mode
      TB0CCTL0 |=  CCIS_2;       // Defaults to compare mode and load on write
    //               |------------- Input set to GND

    // Setup capture/compare block 1 for capture mode
    TB0CCTL1 |= CM_3 | CCIS_1 | CCIE | CAP | SCS;
    //           |      |        |      |     |---- Synchronous capture
    //           |      |        |      |---------- Capture mode, not compare mode
    //           |      |        |---------------- Enable capture interrupt
    //           |      |------------------------- Capture input CCI0B = eCOMP output
    //           |-------------------------------- Capture both edges

    // Timer0_B3 Setup
     TB0CTL |= TBSSEL_1 | ID_2 |  MC_2 | TBCLR;
    //           |         |      |        |---- Clear TB0R and divider logic
    //           |         |      |------------- Timer in continuous mode
    //           |         |-------------------- Input clock divided by 4 (8192 Hz)
    //           |------------------------------ Clock source = ACLK (32768 Hz)

}


//******************************************************************************
//  Software_Trim - To get the best DCOFTRIM value
//******************************************************************************
//  Code provided by TI examples
//******************************************************************************
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
}