CCS/MSP430G2231: msp430g2231 to pwm soft stop

eeengineer

Prodigy 80 points

Part Number: MSP430G2231

Tool/software: Code Composer Studio

hi everyone

i have msp430g2231 chip and i want to software pwm signals for soft stop led light

i researched datasheet and internet but i cant make output pwm signal from its.

could you help me for this .

i use CCS texas program.

P1.1 , P1.2 P1.5 P1.6 P2.6 those pins are i can use pwm signal with Timer_A

#include <msp430g2231.h>

int IncDec_PWM = 1;
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
DCOCTL = 0; // Select lowest DCOx and MODx
BCSCTL1 = CALBC1_1MHZ; // Set range
DCOCTL = CALDCO_1MHZ; // Set DCO step + modulation

P1DIR |= 0x06; // P1.1 and P1.2 output
P1SEL |= 0x06; // P1.1 and P1.2 TA0./1 otions

TA0CCR0 = 1000; // PWM Period/2
TA0CCTL1 = OUTMOD_7; // CCR1 toggle/set
TA0CCR1 = 1; // CCR1 PWM duty cycle
TA0CTL = TASSEL_2 + MC_1; // ACLK, up-down mode

_BIS_SR(LPM3_bits); // Enter LPM3

#pragma vector =TIMER0_A0_VECTOR
__interrupt void TIMER_A0 (void);
{
TA0CCR1 += IncDec_PWM*2; // Increase or decrease duty cycle

if( TA0CCR1 > 998 || TA0CCR1 < 2 ) // Reverse direction if it falls within values
IncDec_PWM = -IncDec_PWM;
}

over 7 years ago

0 Bruce McKenney over 7 years ago

Guru 99235 points

I don't see where you enable interrupts (GIE). Try:
> _BIS_SR(LPM3_bits|GIE); // Enter LPM3 with interrupts enabled

0 Bruce McKenney over 7 years ago in reply to Bruce McKenney

Guru 99235 points

Oh, and you'll also need to enable the CCR0 interrupt:
> TA0CCTL0 = CCIE; // Enable TIMER0_A0_VECTOR interrupt

0 eeengineer over 7 years ago in reply to Bruce McKenney

Prodigy 80 points

Firstly, thank you for interest my problem
I wrote other code for pwm , I took square wave and blik a led.
but i wanto soft stop led (dim led) . could you help me for this?
best regards

#include <msp430g2231.h>

void main(void)
{
WDTCTL = WDTPW | WDTHOLD; // stop watchdog timer
DCOCTL = CALDCO_1MHZ; //SET DCO STEP + MODULATION
BCSCTL1 = CALBC1_1MHZ; //SET RANGE

P1DIR |= BIT2; // P1.2 OUTPUT
P1SEL |= BIT2; // TA0.1 ENABLE
P1OUT |= BIT2; // P1.2 RESISTOR PULL-UP
P1REN |= BIT2; //RESISTOR ENABLE

TACCR0 = 1000; // PWM PERIOD
TACCR1 = 600; // DUTY CYCLE
TACCTL1 = OUTMOD_7; // RESET/SET
TACTL = TASSEL_2 + MC_1 ; //SMCLK, UP MODE,

while(1)
{

}

}

0 Bruce McKenney over 7 years ago in reply to eeengineer

Guru 99235 points

You haven't defined what "soft stop" means, but if it means not just abruptly going to 0% duty cycle, I think you had most of that in your original code -- just stop when you get to 0 ("<2") rather than reversing direction.

One thing I have done in the past is what might be called "soft switch": The control part of the program (presumably main()) sets a variable indicating the target duty cycle, then the CCR0 ISR steps (rather than just switching immediately) towards that target value. This is similar to what your original code did, but with a variable target (not just 0 and 1000). To switch the LED completely off ("softly") you just set the target to 0.

0 eeengineer over 7 years ago in reply to Bruce McKenney

Prodigy 80 points

for example dimmer led

When it is begin to stop led light not immediately stop, softly stop. for example when DC motor is stop softly.

Look at the graphical please.

0 Bruce McKenney over 7 years ago in reply to eeengineer

Guru 99235 points

That's more or less what I guessed. Did you try any of my suggestions?

0 eeengineer over 7 years ago in reply to Bruce McKenney

Prodigy 80 points

Hi again i used yours code but they didn't right work,
When i started debug this messages worning to me.
"MSP430: Can't Single Step Target Program: CPU is currently OFF and debugging capabilities will be limited."
And #pragma vector is didnt work . How can i used Timers for led dimming so soft stop brightness.

#include <msp430.h>
#include <sys/types.h>
#define LED BIT2

volatile uint16_t count;
volatile uint16_t pwm;

int main(void)
{
count=1000, pwm=5000;
WDTCTL = WDTPW | WDTHOLD; // stop watchdog timer

DCOCTL = CALDCO_1MHZ; //SET DCO STEP + MODULATION
BCSCTL1 = CALBC1_1MHZ; //SET RANGE

P1DIR |= LED;
P1SEL |= LED;
P1REN = 1;
P1OUT = 1;

TA0CCTL0 = CCIE; // Enable TIMER0_A0_VECTOR interrupt
TA0CCR0 = 10000; // pwm period
TA0CCR1 = 2000; // duty cycle
TA0CCTL1= OUTMOD_7 | OUT; // reset set mode
TA0CTL = TASSEL_2 | MC_1 | ID_0 ; //SMCLK, UP MODE, DIVIDER/1

__enable_interrupt();
_BIS_SR(LPM3_bits | GIE); // Enter LPM3 with interrupts enabled

#pragma vector=TIMER0_A1_VECTOR
__interrupt void Timer_A1(void);
{

if(count)
{
count--;
}
}

while (1)
{
for(pwm;pwm>0;pwm--)
{

TACCR1=pwm;
__delay_cycles(1000);
TACCR1=0;
}

}

return 0;
}

0 eeengineer over 7 years ago in reply to eeengineer

Prodigy 80 points

Also this messages worning to me too. how can i solve this.

Description Resource Path Location Type
#10443-D null: The ".stack" section size is required to be aligned to 4 bytes, but the specified size, 0x32, is not. The aligned size is 0x34 g2231_pwm C/C++ Problem

0 Bruce McKenney over 7 years ago in reply to eeengineer

Guru 99235 points

You appear to have placed your ISR in the middle of main(). Move it outside. You'll need to get rid of that semicolon (";") on the __interrupt line and change the vector= back to TIMER0_A0_VECTOR.
-----------
Now try adding this

// Add this as a global variable:
volatile unsigned int ccr1_target; // Shared between main and ISR

// then something like this in the ISR:
if (TA0CCR1 < ccr1_target)
  TA0CCR1 += 1; // Step up towards target
else if (TA0CCR1 > ccr1_target)
  TA0CCR1 -= 1; // Step down towards target
else
  /*EMPTY*/; // The target has been reached; don't change TA0CCR1, and maybe notify main()

Then assign ccr1_target to the duty cycle you want (maybe 0) and wait for it to get there.

Keep in mind that this can take a while -- with this TA0CCR0 value 10ms/step -- so delaying for 1000 cycles (1ms) is much too short. I suggest you go back to a 1ms period, both for this and to avoid flicker.

0 eeengineer over 7 years ago in reply to Bruce McKenney

Prodigy 80 points

Hi again

Thank you so much.

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CCS/MSP430G2231: msp430g2231 to pwm soft stop