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MSP430F6721A: Assigning PWM to the chosen pinouts in metering MSP430 SoC's

Expert 5920 points
Other Parts Discussed in Thread: MSP430F6721A

Hello team,

As we discussed offline, can you help to provide a code example on how to assign PWM output signal from TA1.1 to TA1.0 in MSP430F6721A?

Thanks for your help.

msp430f673xA_ta1_20.c

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//******************************************************************************
//  MSP430F673xA Demo - Timer1_A1, PWM TA1.1, Up/Down Mode, 32kHz ACLK
//
//  Description: This program generates a PWM output on P8.5 using
//  Timer1_A configured for up/down mode. The value in CCR0, 128, defines the
//  PWM period/2 and the values in CCR1 the PWM duty cycle. Using
//  32kHz ACLK as TACLK, the timer period is 7.8ms with a 75% duty cycle
//  on P8.5. Normal operating mode is LPM3
//  ACLK = TACLK = LFXT1 = 32768Hz, MCLK = default DCO ~1.045MHz.
//
//              MSP430F673xA
//            ---------------
//        /|\|               |
//         | |               |
//         --|RST            |
//           |               |
//           |     P8.5/TA1.1|--> CCR1 - 75% PWM
//
//  M. Swanson
//  Texas Instruments Inc.
//  December 2011
//  Built with CCS Version: 5.1.0 and IAR Embedded Workbench Version: 5.40.1
//******************************************************************************
#include <msp430.h>

int main(void)
{
    WDTCTL = WDTPW | WDTHOLD;               // Stop WDT

    // Setup P8.5 TA1.1
    P8DIR |= BIT5;                          // P8.5/TA1.1 output
    P8SEL |= BIT5;                          // Output TA1

    // Setup LFXT1
    UCSCTL6 &= ~(XT1OFF);                   // XT1 On
    UCSCTL6 |= XCAP_3;                      // Internal load cap
    // Loop until XT1 fault flag is cleared
    do
    {
        UCSCTL7 &= ~(XT2OFFG | XT1LFOFFG | DCOFFG);
        // Clear XT2,XT1,DCO fault flags
        SFRIFG1 &= ~OFIFG;                  // Clear fault flags
    } while (SFRIFG1 & OFIFG);              // Test oscillator fault flag

    // Setup TA1
    TA1CCR0 = 128;                          // PWM Period/2
    TA1CCTL1 = OUTMOD_6;                    // CCR1 toggle/set
    TA1CCR1 = 32;                           // CCR1 PWM duty cycle
    TA1CTL = TASSEL_1 | MC_3;               // ACLK, up-down mode

    __bis_SR_register(LPM3_bits);           // Enter LPM3
    __no_operation();                       // For debugger
}

  • Hi Bart,

    Which package are you using? Is it the 80-pin or 100-pin package? The reason I ask is because you may need to use port mapping to output the signal if you're using the 80-pin package.

    If you want to use TA1.0 as the timer output, it's more challenging than just using the TA1.1 or TA1.2 outputs. Why? Well, Mode 6 (PWM toggle/set) uses CCR0 as the reference period and then changes CCR1 and CCR2 to achieve different pulse widths if necessary. You'd need to change modes for using TA1.0 as the output.

    You can technically support a PWM output on TA1.0 using TA1CCR0, BUT you will only be able to adjust the duty cycle and the frequency will be fixed.  To use the TA1CCR0 compare circuit, the Timer will need to be operating in Continuous mode which forces the Timer to count from 00000h to 0FFFFh.  Look specifically at Section 17.2.3.2.

    MSP430F5528 PWM on TA1.0 using TA1CCR0

    Thus, I think it'd be easier to use the TA1.2 pin if possible rather than TA1.0.

    Regards,

    James

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