I have an issue where a PWM pulse of varying duration appears before the proper PWM starts. PWMs are on pins PD0 and PD1. I use the eval board buttons to start and stop the PWM. The first time I boot I roughly get the duration of the green pulse. If I stop then start the PWM again the PWM at the start is of different shape and could be the yellow or green trace. I think this is due to the PWM counter being non zero at the start but not sure.
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The start of the PWM should be the yellow trace but the green trace appears prior. Code is:
//To make complimentary PWMs using deadband //Includes #include "inc/tm4c123gh6pm.h" #include <stdint.h> #include <stdbool.h> #include <stdlib.h> #include <string.h> #include <ctype.h> #include "inc/hw_memmap.h" #include "inc/hw_types.h" //#include "inc/hw_ints.h" #include "driverlib/sysctl.h" #include "driverlib/adc.h" #include "driverlib/gpio.h" #include "driverlib/debug.h" #include "driverlib/interrupt.h" #include "driverlib/pwm.h" #include "driverlib/timer.h" //just added in v3 #include "driverlib/pin_map.h" #include "driverlib/uart.h" #include "inc/hw_gpio.h" #include "utils/ustdlib.h" //#include "C:/ti/TivaWare_C_Series-2.1.0.12573/utils/ustdlib.h" //#include "utils/uartstdio.h" //#include "utils/cmdline.h" #include "driverlib/rom.h" void InitPWMs(void); //Frequency stuff unsigned int ui32PWMFreq = 126000;//Default boot frquency void InitPWMs(void) { uint32_t ui32LoadIn; uint32_t ui32PWMDeadband; //Setup for bridge drive with 2 PWMs on M1PWM0 PD0, M1PWM1 PD1 ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM1);//changed from PWM1 ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);//for M1PWM0 M1PWM1 and UART2 //Configure PWM0 on module 1 which is pin PD0 and PWM1 on mondule 1 on pin PD1 ROM_GPIOPinTypePWM(GPIO_PORTD_BASE, GPIO_PIN_0);//Sets PD0 to PWM ROM_GPIOPinTypePWM(GPIO_PORTD_BASE, GPIO_PIN_1);//Sets PD1 to PWM ROM_GPIOPinConfigure(GPIO_PD0_M1PWM0);//Module 1 PWM0 ROM_GPIOPinConfigure(GPIO_PD1_M1PWM1);//Module 1 PWM1 //Setup clock and frequency ui32LoadIn = (ROM_SysCtlClockGet() / ui32PWMFreq);//Determine count to put in timer reg (already has -1 in PWMGenPeriodSet ui32PWMDeadband = ui32LoadIn*5/100;//deadband count //Setup PWM1 ROM_PWMGenConfigure(PWM1_BASE, PWM_GEN_0, PWM_GEN_MODE_DOWN | PWM_GEN_MODE_DBG_RUN |PWM_GEN_MODE_GEN_SYNC_LOCAL | PWM_GEN_MODE_DB_SYNC_LOCAL); //Set PWM period and Duty Cycle ROM_PWMGenPeriodSet(PWM1_BASE, PWM_GEN_0, ui32LoadIn);//Load value into PWM should be 16 bit and already has -1 in funciton ROM_PWMPulseWidthSet(PWM1_BASE, PWM_OUT_0, ui32LoadIn/2);//Sets PWM Pulse Width (DutyCycle) //setup out output enable config for local update //HWREG(0x40029000+0x028)=0b1010; //Setup deadband ROM_PWMDeadBandEnable(PWM1_BASE,PWM_GEN_0,ui32PWMDeadband>>1,ui32PWMDeadband>>1);//Configure deadband on PWM1 PMW0 }//End of InitPWM1 //Start of main---------------------------------------------------------------------- int main(void) { //40MHz clock, use ROM command to save space! ROM_SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_OSC_MAIN|SYSCTL_XTAL_16MHZ); ROM_SysCtlPWMClockSet(SYSCTL_PWMDIV_1);//Sets PWM, set to 40MHz? ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);//Enable clock on peripheral for LEDS //wait for GPIOF module to be ready while(!SysCtlPeripheralReady(SYSCTL_PERIPH_GPIOF)) { } //Config LEDS ROM_GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);//Set PF1,2,3 to output type APB which can toggle every two cycles //Turn LED REd on GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1, 2);//Turn Red LED on //Sets up buttons SW1 and SW2 I think... HWREG(GPIO_PORTF_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY; HWREG(GPIO_PORTF_BASE + GPIO_O_CR) |= 0x01; HWREG(GPIO_PORTF_BASE + GPIO_O_LOCK) = 0; ROM_GPIODirModeSet(GPIO_PORTF_BASE, GPIO_PIN_4|GPIO_PIN_0, GPIO_DIR_MODE_IN); ROM_GPIOPadConfigSet(GPIO_PORTF_BASE, GPIO_PIN_4|GPIO_PIN_0, GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD_WPU); //Enable PWM Module 1 PWM0,PWM1 here InitPWMs(); while(1) { //Turns On PWM if((ROM_GPIOPinRead(GPIO_PORTF_BASE,GPIO_PIN_4)==0x00)) { //Turn on PWM ROM_SysCtlDelay(5000000);//Blocks X seconds? //Turn PWM10 ON ROM_PWMOutputState(PWM1_BASE, PWM_OUT_0_BIT | PWM_OUT_1_BIT , true);//PWM0 set to output //HWREG(0x40029054)=0x0000; ROM_PWMGenEnable(PWM1_BASE, PWM_GEN_0);//Runs PWM }//End of switch1 Turns on PWM //Turns off PWMs if((ROM_GPIOPinRead(GPIO_PORTF_BASE,GPIO_PIN_0)==0x00)) { //Turn off PWM ROM_SysCtlDelay(5000000);//Blocks X seconds? ROM_PWMOutputState(PWM1_BASE, PWM_OUT_0_BIT | PWM_OUT_1_BIT, false);//PWM0 set to output off ROM_PWMGenDisable(PWM1_BASE, PWM_GEN_0);//turns off PWM //Sets PD0 low since seems to off can be high... //Setoutputs low }//End of switch 2 turn off PWM }//end of main while loop }//******************end of main************************
