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Discussion Groups | MSP430 | how to generate variable pwm using msp430x20x1
The purpose of this group is to foster exchange of information on the Texas Instruments MSP430 family of microcontrollers and related tools. Everyone welcome, all levels of familiarity/expertise.
how to generate variable pwm using msp430x20x1 - madh_86 - Aug 25 23:59:08 2009
Hi,I am new to msp430 i dont have any knowledge on embedded programming kindly help me, i
am working on msp430X20X1 to generate varibale pwm but as i debug the program when i am
checking output with CRO at P1.2 i am unable to get varibale pwm i am getting constant
duty cycle of first CCR1 vaule. once the timer is configured in OUTMODE_7 i am unable to
stop it even with CCIE it is not going to ISR.How to use ISR that will return a value with
updated CCR1 register.plz help me out.....
This is the program what i have coded
#include
void main(void)
{
int i,j=90;
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= 0x0C; // P1.2 and P1.3 output
P1SEL |= 0x0C; // P1.2 and P1.3 TA1/2 options
CCR0 = 512-1; // PWM Period
CCTL1 = OUTMOD_7; // CCR1 reset/set
TACTL = TASSEL_2 + MC_1; // SMCLK, up mode
while(1==1)
{
if(CCR1
{
CCR1 = j+30; // CCR1 PWM duty cycle
}
else
{
CCR1=90;
}
}
}_BIS_SR(CPUOFF); // Enter LPM0
}
------------------------------------
(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )
This is the program what i have coded
#include
void main(void)
{
int i,j=90;
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= 0x0C; // P1.2 and P1.3 output
P1SEL |= 0x0C; // P1.2 and P1.3 TA1/2 options
CCR0 = 512-1; // PWM Period
CCTL1 = OUTMOD_7; // CCR1 reset/set
TACTL = TASSEL_2 + MC_1; // SMCLK, up mode
while(1==1)
{
if(CCR1
{
CCR1 = j+30; // CCR1 PWM duty cycle
}
else
{
CCR1=90;
}
}
}_BIS_SR(CPUOFF); // Enter LPM0
}
------------------------------------
(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )
Re: how to generate variable pwm using msp430x20x1 - old_cow_yellow - Aug 26 2:37:52 2009
Very strange code!
You set CCR0 to 512-1 and use up mode, it takes 512 clocks to generate a single pulse. But before that pulse is generated, you "changed" the pulse-width (CCR1)dozens of times. Each time you "changed" it to the same value 90+30=120. So goes the next pulse, and the next, etc. Thus the period is always 512, and the pulse width keeps "changing" all the time to the same 120.
--- In m...@yahoogroups.com, "madh_86" wrote:
>
> Hi,I am new to msp430 i dont have any knowledge on embedded programming kindly help me, i am working on msp430X20X1 to generate varibale pwm but as i debug the program when i am checking output with CRO at P1.2 i am unable to get varibale pwm i am getting constant duty cycle of first CCR1 vaule. once the timer is configured in OUTMODE_7 i am unable to stop it even with CCIE it is not going to ISR.How to use ISR that will return a value with updated CCR1 register.plz help me out.....
>
> This is the program what i have coded
>
> #include void main(void)
>
> {
>
> int i,j=90;
>
> WDTCTL = WDTPW + WDTHOLD; // Stop WDT
>
> P1DIR |= 0x0C; // P1.2 and P1.3 output
>
> P1SEL |= 0x0C; // P1.2 and P1.3 TA1/2 options
>
> CCR0 = 512-1; // PWM Period
>
> CCTL1 = OUTMOD_7; // CCR1 reset/set
>
> TACTL = TASSEL_2 + MC_1; // SMCLK, up mode
>
> while(1==1)
>
> {
>
> if(CCR1
> {
>
> CCR1 = j+30; // CCR1 PWM duty cycle
>
> }
>
> else
>
> {
>
> CCR1=90;
>
> }
>
> }
>
> }_BIS_SR(CPUOFF); // Enter LPM0
>
> }
>
------------------------------------
______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.
(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )
You set CCR0 to 512-1 and use up mode, it takes 512 clocks to generate a single pulse. But before that pulse is generated, you "changed" the pulse-width (CCR1)dozens of times. Each time you "changed" it to the same value 90+30=120. So goes the next pulse, and the next, etc. Thus the period is always 512, and the pulse width keeps "changing" all the time to the same 120.
--- In m...@yahoogroups.com, "madh_86"
>
> Hi,I am new to msp430 i dont have any knowledge on embedded programming kindly help me, i am working on msp430X20X1 to generate varibale pwm but as i debug the program when i am checking output with CRO at P1.2 i am unable to get varibale pwm i am getting constant duty cycle of first CCR1 vaule. once the timer is configured in OUTMODE_7 i am unable to stop it even with CCIE it is not going to ISR.How to use ISR that will return a value with updated CCR1 register.plz help me out.....
>
> This is the program what i have coded
>
> #include
>
> {
>
> int i,j=90;
>
> WDTCTL = WDTPW + WDTHOLD; // Stop WDT
>
> P1DIR |= 0x0C; // P1.2 and P1.3 output
>
> P1SEL |= 0x0C; // P1.2 and P1.3 TA1/2 options
>
> CCR0 = 512-1; // PWM Period
>
> CCTL1 = OUTMOD_7; // CCR1 reset/set
>
> TACTL = TASSEL_2 + MC_1; // SMCLK, up mode
>
> while(1==1)
>
> {
>
> if(CCR1
> {
>
> CCR1 = j+30; // CCR1 PWM duty cycle
>
> }
>
> else
>
> {
>
> CCR1=90;
>
> }
>
> }
>
> }_BIS_SR(CPUOFF); // Enter LPM0
>
> }
>
------------------------------------
______________________________
Stellaris® MCU Family: New Parts, New Package, New Price.
(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )