//
// Set the clocking to run directly from the crystal.
//
SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_6MHZ);
// SysCtlPWMClockSet(SYSCTL_PWMDIV_1);

SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM);


//////////////////////////////PWM INIT//////////////////////////////
// 1 - Enable the PWM clock by writing a value of 0x0010.0000
// to the RCGC0 register in the System Control module.

SYSCTL_RCGC0_R = 0x00100000;

// 2 - In the GPIO module, enable the appropriate
// pins for their alternate function using the GPIOAFSEL register.

GPIO_PORTB_AFSEL_R = 3; // enable alternate function

// 3 - Configure the Run-Mode Clock Configuration (RCC)
// register in the System Control module
// to use the PWM divide (USEPWMDIV) and set the divider
// PWMDIV) to divide by 2 (000).

SYSCTL_RCC_R = 0x00D03AC0; //USEPWMDIV set /2


// 4 - Configure the PWM generator for countdown mode with immediate
//updates to the parameters.
//¦ Write the PWM0CTL register with a value of 0x0000.0000.
//¦ Write the PWM0GENA register with a value of 0x0000.008C.

PWM_2_CTL_R = 0;

PWM_2_GENA_R = 0x0000008C;
PWM_2_GENB_R = 0x0000080C;

// 5 - Set the period. For a 25-KHz frequency,
// the period = 1/25,000, or 40 microseconds. The PWM
// clock source is 10 MHz; the system clock divided by 2.
// This translates to 400 clock ticks per
// period. Use this value to set the PWM0LOAD register.
// In Count-Down mode, set the Load field
// in the PWM0LOAD register to the requested period minus one.
// Write the PWM0LOAD register with a value of 0x0000.018F

PWM_2_LOAD_R = 0x0000018F; //400


// 6 - Set the pulse width of the PWM1 pin for a 25% duty cycle.
// ¦ Write the PWM0CMPA register with a value of 0x0000.012B.

PWM_2_CMPA_R = 0x0000012B; // 300
PWM_2_CMPB_R = 0x00000063; //100

// 8 - Start the timers in PWM generator 1.
// ¦ Write the PWM0CTL register with a value of 0x0000.0001.

PWM_2_CTL_R = 0x01;// update

// 9 - Enable PWM outputs.

PWM_ENABLE_R = 0x3F;

while (1)
{}