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CCS/MSP430FR4133: PWM for P1.0 or P4.0

Daniel Warner
Prodigy 150 points
Part Number: MSP430FR4133


Tool/software: Code Composer Studio

int main(void) {
		WDTCTL = WDTPW | WDTHOLD;               // Stop watchdog timer
		P1DIR |= 0x00; //Set pin 1.0 to the output direction.
	    P1SEL0 |= 0x00; //Select pin 1.0 as our PWM output.
	    TA0CCR0 = 1000-1; //Set the period in the Timer A0 Capture/Compare 0 register to 1000 us.
	    TA0CCTL1 = OUTMOD_7;
	    TA0CCR1 = 800; //The period in microseconds that the power is ON. It's half the time, which translates to a 50% duty cycle.
	    TA0CTL = TASSEL_2 + MC_1; //TASSEL_2 selects SMCLK as the clock source, and MC_1 tells it to count up to the value in TA0CCR0.
	    __bis_SR_register(LPM0_bits); //Switch to low power mode 0.
}

The LED 1.0 doesn't work in PWM-mode. Also if I change the code to:

int main(void) {
		WDTCTL = WDTPW | WDTHOLD;               // Stop watchdog timer
		P1DIR |= 0x04; //Set pin 1.2 to the output direction.
	    P1SEL0 |= 0x04; //Select pin 1.2 as our PWM output.
	    TA0CCR0 = 1000-1; //Set the period in the Timer A0 Capture/Compare 0 register to 1000 us.
	    TA0CCTL1 = OUTMOD_7;
	    TA0CCR1 = 800; //The period in microseconds that the power is ON. It's half the time, which translates to a 50% duty cycle.
	    TA0CTL = TASSEL_2 + MC_1; //TASSEL_2 selects SMCLK as the clock source, and MC_1 tells it to count up to the value in TA0CCR0.
	    __bis_SR_register(LPM0_bits); //Switch to low power mode 0.
}

...there is no function of the connected LED.

Does the MSPFR4133 supports the PWM-mode to this qutputs?
  • 0
    Guru 100405 points

    As I read the data sheet, P1.0 is not connected to any timer, and so can't be used for (hardware) PWM output.

    P4.0 is TA1.1, i.e. it is controlled using TA1CCR1/TA1CCTL1, and connected to TimerA1 by setting BIT0 of P4DIR and P4SEL0 (per SLAS865B Table 6-17):

    TA1CCR0 = 1000-1;
    TA1CCTL1 = OUTMOD7; // TA1.1
    TA1CCR1 = 800;
    TA1CTL = TASSEL_2 | MC_1;
    P4DIR |= BIT0; // P4.0
    P4SEL0 |= BIT0;

  • 0 in reply to Bruce McKenney
    Prodigy 150 points
    Thx for your reply, but it didn't work. Maybe I should try P1.5 tp P1.7 according to Table 6-14 with TA0-1....
  • 0 in reply to Daniel Warner
    Guru 100405 points
    Oh, I forgot

    PM5CTL0 &= ~LOCKLPM5;

    I was reminded of this by the example code; there's a link to it on the product page.
  • 0 in reply to Bruce McKenney
    Prodigy 150 points
    Hi Bruce,
    here is my full code, but even with your last hint it didn't work. The only thing what happened was P4.0 is activated and remains in this state.

    #include <msp430fr4133.h>
    #include <driverlib.h>
    #include "main.h"
    #include "hal_LCD.h"
    #include <stdio.h>
    #include <stdlib.h>

    void main(void)
    {
    while(1)
    {
    WDTCTL = WDTPW + WDTHOLD; // Stop WDT
    PM5CTL0 &= ~LOCKLPM5;

    TA1CCR0 = 512-1;
    TA1CCR1 = 200;
    TA1CTL = TASSEL_2 | MC_1;
    TA1CCTL1 = OUTMOD_7;

    P4DIR |= BIT0; // P4.0
    P4SEL0 |= BIT0;
    __bis_SR_register(LPM0_bits); //Switch to low power mode 0.
    }
    }
  • 0 in reply to Daniel Warner
    Guru 100405 points
    I'm not sure what you expect to happen.

    I expect that the P4.0 LED will come on at about 40% (200/512) brightness and stay there indefinitely. It sounds as though that is what is happening.

    If you want the LED brightness to vary, you need to change TA1CCR1.
  • 0 in reply to Bruce McKenney
    Prodigy 150 points

    Here is my code, what increase the brightness. I have had a wrong understanding of PWM with a LED.

    #include <msp430fr4133.h>
#include <driverlib.h>
#include "main.h"
#include "hal_LCD.h"
#include <stdio.h>
#include <stdlib.h>

void main(void)
{
while(1)
	{
	WDTCTL = WDTPW + WDTHOLD; // Stop WDT
	PM5CTL0 &= ~LOCKLPM5;

	TA1CCR0 = 1000-1;
	TA1CCR1 = 0;
	TA1CTL = TASSEL_2 | MC_1;
	TA1CCTL1 = OUTMOD_7;

	P4DIR |= BIT0; // P4.0
	P4SEL0 |= BIT0;

	while (TA1CCR1<900)
	{
		TA1CCR1 ++;
		_delay_cycles(80000);
	}
	//__bis_SR_register(LPM0_bits); //Switch to low power mode 0.
	}
}

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