I'm using a EK-TM4C123GXL board to run a tower pro sg90 servo motor.My system clock is running at 16Mhz and im using Keil to program.Given below is the code I wrote, but there is no movement on the servo.
#include "tm4c123gh6pm.h" //header file, tm4c123gh6pm register descriptions
/***************************************Definition************************************/
#define SIGNAL (01U << 7) //PWM signal
#define LOAD 0x270FF //LOAD value = 159,999
/***************************************************************************************/
void PWM_init()
//PWM_init function enables PWM at PortB7 to work in a countdown mode.
{
SYSCTL_RCGC0_R |= SYSCTL_RCGC0_PWM0; //Enable pwm clock
SYSCTL_RCGC2_R |= SYSCTL_RCGC2_GPIOB; //PORT B clock enable
__asm{nop
nop} //Two NOP delay to stabilize clock (Mixed ASM C Programming)
GPIO_PORTB_DIR_R |= SIGNAL; //Set the B7 pin as output
GPIO_PORTB_AFSEL_R |= SIGNAL; //Enable Alternate function for B7
GPIO_PORTB_PCTL_R &= ~(GPIO_PCTL_PB7_M); //PORT mux control for PB7 - Clear bit
GPIO_PORTB_PCTL_R |= GPIO_PCTL_PB7_M0PWM1; //PORT mux control for PB7 - set PWM
GPIO_PORTB_DATA_R |= SIGNAL; //Data enable for PB7
SYSCTL_RCC_R |= SYSCTL_RCC_USEPWMDIV; //Enable PWM divider
SYSCTL_RCC_R &= ~(SYSCTL_RCC_PWMDIV_M); //Clear PWM divider filed
SYSCTL_RCC_R |= SYSCTL_RCC_PWMDIV_2; //Set PWM divide as /2
PWM0_1_CTL_R = 0x00000000; //Disable PWM timer
//Masking the action for Bdown & counter = LOAD
PWM0_1_GENB_R &=~(PWM_0_GENB_ACTCMPBD_M | PWM_0_GENB_ACTLOAD_M);
PWM0_1_GENB_R |= (PWM_0_GENB_ACTLOAD_ONE | PWM_0_GENB_ACTCMPBD_ZERO);
PWM0_1_LOAD_R = LOAD; //LOAD value set as 159,999
PWM0_1_CMPB_R = LOAD*(0.9); //Initial value for comparator B is 0.9*LOAD
PWM0_1_CTL_R = PWM_0_CTL_ENABLE; //Enable PWM timer
PWM0_ENABLE_R = PWM_ENABLE_PWM1EN; //Enable PWM
}
int main()
{
PWM_init();
}
Please can somebody tell me whats wrong in the code?
