Problem with generating PWM pulses on LPC2148 microprocessors

[jeevanmgp]

Hi, I am having some trouble with PWM on LPC2148 microprocessors. Pulses are not generated. It is a complete high signal. Here is the code I am using.
/* Oscillator frequency 12.000 Mhz */
/* Target board Keil MCB2100 */
/************************************************************/

#include "LPC214X.H"
#include "FreeRTOSConfig.h"


static int pwmPulseWidth = 2000;
static int pwmPercentage = 50;

int pwmDutyCycle (int percentage);
int pwmPulseWidthInMicroseconds (int us);
int pwmFrequency (int frequency);
void pwmInit (void);

//
//
//
int pwmDutyCycle (int percentage)
{
if ((percentage < 0) || (percentage > 100))
return -1;

PWM_MR5 = ((configCPU_CLOCK_HZ / pwmPulseWidth) * (pwmPercentage = percentage)) / 100;
PWM_LER = PWM_LER_M5L;

return 0;
}

//
//
//
int pwmPulseWidthInMicroseconds (int us)
{
unsigned int count = (configCPU_CLOCK_HZ / 1000000) * us;

if (count > PWM_MR0)
return -1;

PWM_MR5 = count;
PWM_LER = PWM_LER_M5L;

return 0;
}

//
//
//
int pwmFrequency (int frequency)
{
if ((frequency < 1) || (frequency >= (int) configCPU_CLOCK_HZ))
return -1;

PWM_MR0 = (configCPU_CLOCK_HZ / (pwmPulseWidth = frequency));
PWM_MR5 = ((configCPU_CLOCK_HZ / pwmPulseWidth) * pwmPercentage) / 100;
PWM_LER = PWM_LER_M5L | PWM_LER_M0L;

return 0;
}



void pwmInit (void)
{
SCB_PCONP |= SCB_PCONP_PCPWM0;
PCB_PINSEL1 = (PCB_PINSEL1 & ~PCB_PINSEL1_P021_MASK) | PCB_PINSEL1_P021_PWM5;

PWM_TCR = PWM_TCR_CR;
PWM_PR = 0;
PWM_MR0 = (configCPU_CLOCK_HZ / pwmPulseWidth);
PWM_MCR |= PWM_MCR_MR0R;
PWM_PCR |= PWM_PCR_ENA5;
PWM_TCR = (PWM_TCR_CE | PWM_TCR_PWME);

pwmDutyCycle (50);
}

void init_pll()
{
PLL0CFG = 0x00000025;
PLL0CON = 0x00000001;
PLL0FEED = 0x0000000AA;
PLL0FEED = 0x000000055;
while (!(PLL0STAT & 0x00000400));
PLL0CON = 0x00000003;
PLL0FEED = 0x0000000AA;
PLL0FEED = 0x000000055;
VPBDIV = 0x00000001;
}


void main()
{
init_pll();
pwmInit();
pwmFrequency (50);
pwmPulseWidthInMicroseconds(2000);
pwmDutyCycle(50);
while(1)
{


}

}

 

[bobcat1]

Re: PWM in LPC2148

HI

You need to setup the I/O pin as peripheral to see PWM out put
Also add some notes to your code it will be easy to understand

All the best

Bobi

 

[binojkumar]

Re: PWM in LPC2148

Configure ur PINSEL register for PWM output..
By default those bits configured for GPIOs.

 

[sushil909]

Re: PWM in LPC2148

Configure ur PINSEL register for PWM output..
By default those bits configured for GPIOs.

Even i am having the same problem. I even set PINSEL1 to take pin p0.21 as PWM5.

When i simulate it inside keil i see that the PWM is working. When i check it inside the peripheral for PWM i see the PWM5 going on and off. But there is no signal in the real hardware.

I am been stuck for a while on this. Could somebody please help me.