pwmgen.c

Stellaris公司推出1美元ARM,这是Stellaris驱动库源程序

//*****************************************************************************
//
// pwmgen.c - PWM signal generation example.
//
// Copyright (c) 2005,2006 Luminary Micro, Inc.  All rights reserved.
//
// Software License Agreement
//
// Luminary Micro, Inc. (LMI) is supplying this software for use solely and
// exclusively on LMI's Stellaris Family of microcontroller products.
//
// The software is owned by LMI and/or its suppliers, and is protected under
// applicable copyright laws.  All rights are reserved.  Any use in violation
// of the foregoing restrictions may subject the user to criminal sanctions
// under applicable laws, as well as to civil liability for the breach of the
// terms and conditions of this license.
//
// THIS SOFTWARE IS PROVIDED "AS IS".  NO WARRANTIES, WHETHER EXPRESS, IMPLIED
// OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE.
// LMI SHALL NOT, IN ANY CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR
// CONSEQUENTIAL DAMAGES, FOR ANY REASON WHATSOEVER.
//
// This is part of revision 920 of the Stellaris Driver Library.
//
//*****************************************************************************

#include "../../hw_memmap.h"
#include "../../hw_types.h"
#include "../../src/debug.h"
#include "../../src/gpio.h"
#include "../../src/pwm.h"
#include "../../src/sysctl.h"
#include "../../utils/diag.h"
#include "../osram96x16.h"

//*****************************************************************************
//
//! \addtogroup ev_lm3s811_list
//! <h1>PWM (pwmgen)</h1>
//!
//! This example application utilizes the PWM peripheral to output a 25% duty
//! cycle PWM signal and a 75% duty cycle PWM signal, both at 50 kHz.  Once
//! configured, the application enters an infinite loop, doing nothing while
//! the PWM peripheral continues to output its signals.
//
//*****************************************************************************

//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, unsigned long ulLine)
{
}
#endif

//*****************************************************************************
//
// This example demonstrates how to setup the PWM block to generate signals.
//
//*****************************************************************************
int
main(void)
{
    unsigned long ulPeriod;

    //
    // 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);

    //
    // Initialize the OLED display.
    //
    OSRAMInit(false);

    //
    // Bail out if there is not a PWM peripheral on this part.
    //
    if(!SysCtlPeripheralPresent(SYSCTL_PERIPH_PWM))
    {
        OSRAMStringDraw("This part has no", 0, 0);
        OSRAMStringDraw("PWM", 36, 1);
        DiagExit(0);
    }

    //
    // Clear the screen and thell the user what is happening.
    //
    OSRAMStringDraw("Generating PWM", 6, 0);
    OSRAMStringDraw("on PD0 and PD1", 6, 1);

    //
    // Enable the peripherals used by this example.
    //
    SysCtlPeripheralEnable(SYSCTL_PERIPH_PWM);
    SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOD);

    //
    // Set GPIO D0 and D1 as PWM pins.  They are used to output the PWM0 and
    // PWM1 signals.
    //
    GPIOPinTypePWM(GPIO_PORTD_BASE, GPIO_PIN_0 | GPIO_PIN_1);

    //
    // Compute the PWM period based on the system clock.
    //
    ulPeriod = SysCtlClockGet() / 50000;

    //
    // Set the PWM period to 50 kHz.
    //
    PWMGenConfigure(PWM_BASE, PWM_GEN_0,
                    PWM_GEN_MODE_UP_DOWN | PWM_GEN_MODE_NO_SYNC);
    PWMGenPeriodSet(PWM_BASE, PWM_GEN_0, ulPeriod);

    //
    // Set PWM0 to a duty cycle of 25% and PWM1 to a duty cycle of 75%.
    //
    PWMPulseWidthSet(PWM_BASE, PWM_OUT_0, ulPeriod / 4);
    PWMPulseWidthSet(PWM_BASE, PWM_OUT_1, ulPeriod * 3 / 4);

    //
    // Enable the PWM0 and PWM1 output signals.
    //
    PWMOutputState(PWM_BASE, PWM_OUT_0_BIT | PWM_OUT_1_BIT, true);

    //
    // Enable the PWM generator.
    //
    PWMGenEnable(PWM_BASE, PWM_GEN_0);

    //
    // Loop forever while the PWM signals are generated.
    //
    while(1)
    {
    }
}