2 PWM outputs on Tiva C Launchboard

Hi,

PB7 is in PWM base 0,  generator 0. So you got that wrong. Check Table 20-1

I imagen you are using the tm4c123 launchpad? remember that now there is another tiva launchpad

Thanks for your answer. I tried to change my pwm1_init() and pwm1_start() as follows :

void pwm0_init()
{
    SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
    GPIOPinConfigure(GPIO_PB6_M0PWM0);
    GPIOPinTypePWM(GPIO_PORTB_BASE, GPIO_PIN_6);
    PWMGenConfigure(PWM0_BASE, PWM_GEN_0, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
}

void pwm1_init()
{
    SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
    GPIOPinConfigure(GPIO_PB4_M0PWM2);
    GPIOPinTypePWM(GPIO_PORTB_BASE, GPIO_PIN_4);
    PWMGenConfigure(PWM0_BASE, PWM_GEN_1, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
}

void pwm0_start(unsigned long frequence, unsigned long duty_cycle)
{
    PWMGenPeriodSet(PWM0_BASE, PWM_GEN_0, ROM_SysCtlClockGet() / frequence);
    PWMPulseWidthSet(PWM0_BASE, PWM_OUT_0, (PWMGenPeriodGet(PWM0_BASE, PWM_OUT_0) * duty_cycle) / 100);
    PWMOutputState(PWM0_BASE, PWM_OUT_0_BIT, true);
    PWMGenEnable(PWM0_BASE, PWM_GEN_0);
}

void pwm1_start(unsigned long frequence, unsigned long duty_cycle)
{
	PWMGenPeriodSet(PWM0_BASE, PWM_GEN_(1, ROM_SysCtlClockGet() / frequence);
	PWMPulseWidthSet(PWM0_BASE, PWM_OUT_2, (PWMGenPeriodGet(PWM0_BASE, PWM_OUT_2) * duty_cycle) / 100);
	PWMOutputState(PWM0_BASE, PWM_OUT_2_BIT, true);
	PWMGenEnable(PWM0_BASE, PWM_GEN_1);
}

I still can't make this pwm1 work and I don't see why. What do you think about it?

Thanks,

Florent

PS : Yes it's the Tiva TM4C123GH6PM I'm using.

Hello Florent

What is the System Clock Frequency being used and what is the value of "frequence"?

Regards

Amit

Here is the main function where this information is :

int main(void)
{
	ROM_FPUEnable();
	ROM_FPULazyStackingEnable();

	ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
					   SYSCTL_XTAL_16MHZ);
	
    pwm0_init(); // PWM0
    pwm1_init(); // PWM1

    pwm0_start(1000,50); //1kHz, 50% duty cycle
    pwm1_start(1000,50); //1kHz, 50% duty cycle

    while(1)
    {
    }
}

The system clock is 16MHz and the frequence is 1kHz.

Regards,

Florent

Hello Florent,

Attached is the updated c file. I ran it on the LaunchPad and connected the output of the two PWM signals to the Blue and Red LED's and both of them are glowing fine. I did notice there was an error in the code due to the missing "{".

#include "stdint.h"
#include "stdbool.h"
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/fpu.h"
#include "driverlib/sysctl.h"
#include "driverlib/interrupt.h"
#include "driverlib/gpio.h"
#include "driverlib/timer.h"
#include "driverlib/pwm.c"
#include "driverlib/pwm.h"
#include "driverlib/pin_map.h"

void pwm0_init()
{
    SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
    GPIOPinConfigure(GPIO_PB6_M0PWM0);
    GPIOPinTypePWM(GPIO_PORTB_BASE, GPIO_PIN_6);
    PWMGenConfigure(PWM0_BASE, PWM_GEN_0, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
}
void pwm1_init()
{
    SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM0);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
    GPIOPinConfigure(GPIO_PB4_M0PWM2);
    GPIOPinTypePWM(GPIO_PORTB_BASE, GPIO_PIN_4);
    PWMGenConfigure(PWM0_BASE, PWM_GEN_1, PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
}
void pwm0_start(unsigned long frequence, unsigned long duty_cycle)
{
    PWMGenPeriodSet(PWM0_BASE, PWM_GEN_0, SysCtlClockGet() / frequence);
    PWMPulseWidthSet(PWM0_BASE, PWM_OUT_0, (PWMGenPeriodGet(PWM0_BASE, PWM_OUT_0) * duty_cycle) / 100);
    PWMOutputState(PWM0_BASE, PWM_OUT_0_BIT, true);
    PWMGenEnable(PWM0_BASE, PWM_GEN_0);
}
void pwm1_start(unsigned long frequence, unsigned long duty_cycle)
{
    PWMGenPeriodSet(PWM0_BASE, PWM_GEN_1, SysCtlClockGet() / frequence);
    PWMPulseWidthSet(PWM0_BASE, PWM_OUT_2, (PWMGenPeriodGet(PWM0_BASE, PWM_OUT_2) * duty_cycle) / 100);
    PWMOutputState(PWM0_BASE, PWM_OUT_2_BIT, true);
    PWMGenEnable(PWM0_BASE, PWM_GEN_1);
}

int main(void)
{
    FPUEnable();
    FPULazyStackingEnable();
    SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
                       SYSCTL_XTAL_16MHZ);

    pwm0_init(); // PWM0
    pwm1_init(); // PWM1
    pwm0_start(1000,50); //1kHz, 50% duty cycle
    pwm1_start(1000,50); //1kHz, 50% duty cycle
    while(1)
    {
    }
}

Regards

Amit

Thank you for your answer Amit,

I put the exact same code as you uploaded above, connected one probe of my scope to PB6 and one to PB4. Only the one on PB6 provides me the square wave.
I also tried to use another Launchpad but the problem remains the same.

May you try to visualise your 2 pwm on a scope ?

Regards,

Florent

Hello Amit,

Everything works perfectly now. Thank you for your help!

Regards,

Florent