Two pwm signal with 180 degree phase shift USING msp430g2553

Thank you for the reply..!!

Weather this is possible with single timer or i have to use two timer for this operation.?

Thank you so much..!!

I have gone through the user's guide of MSP430G2553.

This method is possible when we operate Timer in UP-DOWN Mode, where i can get the dead band also but i have NO clue as how to get this done using timer in UP MODE.

Any suggestion is highly appreciable.!!

I have written code for the same by using Timer_A1 in up down mode. Since i don't want the dead time stuff, i have used same duty cycle in CCR1 and CCR2.

Can you please verify the same if possible as i don't have oscilloscope to check the output now OR can u suggest the alternate method as how to verify the same without oscilloscope at present.

My code is given below:

void timer_init(void)

{

 P2DIR |= BIT1|BIT4;                          //set as output pin P2.1/TA1.1(O/P OF CCR1 Register), P2.4/TA1.2(O/P OF CCR2 Register)

 P2SEL |= BIT1|BIT4;                         //pin selected for special purpose; here for pwm

 TA1CTL |= TASSEL_2 + MC_3;       //SMCLK and up down mode

TA1CCR0 |= 160 ;                             //pwm frequency 100 khz; DCO = MCLK = SMCLK = 16 Mhz i.e. 16M/160 = 100KHZ

 TA1CCR1 |= Duty;                              //VARIABLE Duty cycle

 TA1CCR2 |= Duty;                               // VARIBLE Duty Cycle

 TA1CCTL1 |= OUTMOD_6;               // TA1CCR1, toggle/set

 TA1CCTL2 |= OUTMOD_2;              // TA1CCR2, toggle/reset

}

Pin Diagram of MSP430G2553:

NOTE: I have used TIMER_A1 in UP DOWN MODE and i want the output as shown below.

Thank you in advance..!!

Thank you for the reply.!!

What parameters will be affected by generating 2 PWM signal with 180 degree phase shift by using only 1 timer in comparison to generating 2 PWM signal with 180 degree phase shift using both the TIMER_A0 and TIMER_A1.

Is there really any difference in max PWM width etc.

Which one is a better option?

First of all thank you so much for the reply..!

I am stuck in this PWM generation for so long and want to come out of it asap.

Using UP MODE is not a concern. I can use any mode. I just want to generate 2 PWM signal with 180 degree phase shift.

NOTE: Duty cycle of PWM will vary as per application need.

I made function for 2 PWM generation. one by using only one timer and other by using two timer, which is written below

USING ONLY 1 TIMER_A1

void timer_init(void)

{

P2DIR |= BIT1|BIT4;                                //set as output pin (P2.1 and P2.4)
P2SEL |= BIT1|BIT4;                                //pin selected for PWM operations (P2.1/TA1.1 AND P2.4/TA1.2)

TA1CTL |= TASSEL_2 + MC_1;            //SMCLK and up mode count till ccr register
TA1CCR0 = 160 - 1;                             //pwm frequency 100 khz; DCO = MCLK = SMCLK = 16 Mhz
TA1CCR1 = Duty;                               //Duty cycle 
TA1CCR2 = Duty;                               //Duty cycle 
TA1CCTL1 = OUTMOD_3;               //set/reset mode 
TA1CCTL2 = OUTMOD_7;               //reset/set mode

}

USING 2 TIMERS, TIMER_A0 AND TIMER_A1

void timer_init(void)

{

P2DIR |= BIT1|BIT6;                                //set as output pin (P2.1 AND P2.6)
P2SEL |= BIT1|BIT6;                                //pin selected for PWM operations (P2.1/TA1.1 AND P2.6/TA0.1)

TA0CTL |= TASSEL_2 + MC_1;            //SMCLK and up mode count till ccr register
TA0CCR0 = 160 - 1;                             //pwm frequency 100 khz; DCO = MCLK = SMCLK = 16 Mhz
TA0CCR1 = Duty;                               //Duty cycle 

TA1CTL |= TASSEL_2 + MC_1;            //SMCLK and up mode count till ccr register
TA1CCR0 = 160 - 1;                             //pwm frequency 100 khz; DCO = MCLK = SMCLK = 16 Mhz
TA1CCR1 = Duty;                               //Duty cycle 

TA0CCTL1 = TA1CCTL1 = OUTMOD_7;               //reset/set mode 

}

Can you please confirm whether both the functions are correct or am i missing something??

Moreover as per your previous reply can i consider that using two timer is a better option in comparison to using only one timer as it will provide more range of CCR value. so, i will get more range of duty cycle variation??

 

Thank you Clemens Ladisch in advance.

 

Hi,

i have modified the last line of the  second function as given below

TA0CCTL1 =  OUTMOD_3;

TA1CCTL1 = OUTMOD_7;

Now, as you said "Two timers do not give you more range for the duty cycle, because both use the same PWM frequency (160 ticks)."

So, what is the advantage of using two timer instead of a single timer as two PWM signals of different duty cycle can be generated by a single timer too having three CCR. Any specific reason to use two timers??

Thank  you..!!

Thank you so much, i got it completely... It's better to use one timer as there is no need for synchronizing the time base. Moreover, it's a bit complex to synchronize the two time base. So, i have no other option left, but to use single timer for such application and luckily msp430g2553 has three CCR'S.
Thank you again..!!