用SAM-BA或JLINK跑ATSAM4E16的程序(9)寄存器PWM

在这个程序里，利用PWM点亮两个LED。

而这两个LED的PWM定义及GPIO的第几功能在

以下宏中定义：


/** PWM LED1 pin definitions. */
#define PIN_PWM_LED1_GPIO     PIO_PC20_IDX
#define PIN_PWM_LED1_FLAGS    (IOPORT_MODE_MUX_B)
#define PIN_PWM_LED1_CHANNEL  PWM_CHANNEL_2

/** PWM LED0 pin definitions. */
#define PIN_PWM_LED0_GPIO     PIO_PA0_IDX
#define PIN_PWM_LED0_FLAGS    (IOPORT_MODE_MUX_A)
#define PIN_PWM_LED0_CHANNEL  PWM_CHANNEL_0

以LED1为例，其数据手册，通道B正好是PWM通道2




这样PWM就同LED连接上了。

以下是程序：

复制

#include "asf.h"

#include "stdio_serial.h"

#include "conf_board.h"

#include "conf_clock.h"



/** PWM frequency in Hz */

#define PWM_FREQUENCY      1000

/** Period value of PWM output waveform */

#define PERIOD_VALUE       100

/** Initial duty cycle value */

#define INIT_DUTY_VALUE    0



#define STRING_EOL    "\r"

#define STRING_HEADER "-- PWM LED Example --\r\n" \

                "-- "BOARD_NAME" --\r\n" \

                "-- Compiled: "__DATE__" "__TIME__" --"STRING_EOL



/** PWM channel instance for LEDs */

pwm_channel_t g_pwm_channel_led;



/**

 * \brief Interrupt handler for the PWM controller.

 */

void PWM_Handler(void)

{

        static uint32_t ul_count = 0;  /* PWM counter value */

        static uint32_t ul_duty = INIT_DUTY_VALUE;  /* PWM duty cycle rate */

        static uint8_t fade_in = 1;  /* LED fade in flag */

        uint32_t events = pwm_channel_get_interrupt_status(PWM);



        /* Interrupt on PIN_PWM_LED0_CHANNEL */

        if ((events & (1 << PIN_PWM_LED0_CHANNEL)) ==

                        (1 << PIN_PWM_LED0_CHANNEL)) {

                ul_count++;



                /* Fade in/out */

                if (ul_count == (PWM_FREQUENCY / (PERIOD_VALUE - INIT_DUTY_VALUE))) {

                        /* Fade in */

                        if (fade_in) {

                                ul_duty++;

                                if (ul_duty == PERIOD_VALUE) {

                                        fade_in = 0;

                                }

                        } else {

                                /* Fade out */

                                ul_duty--;

                                if (ul_duty == INIT_DUTY_VALUE) {

                                        fade_in = 1;

                                }

                        }



                        /* Set new duty cycle */

                        ul_count = 0;

                        g_pwm_channel_led.channel = PIN_PWM_LED0_CHANNEL;

                        pwm_channel_update_duty(PWM, &g_pwm_channel_led, ul_duty);

                        g_pwm_channel_led.channel = PIN_PWM_LED1_CHANNEL;

                        pwm_channel_update_duty(PWM, &g_pwm_channel_led, ul_duty);

                }

        }

}



/**

 *  \brief Configure the Console UART.

 */

static void configure_console(void)

{

        const usart_serial_options_t uart_serial_options = {

                .baudrate = CONF_UART_BAUDRATE,

                .paritytype = CONF_UART_PARITY

        };



        /* Configure console UART. */

        sysclk_enable_peripheral_clock(CONSOLE_UART_ID);

        stdio_serial_init(CONF_UART, &uart_serial_options);

}



/**

 * \brief Application entry point for PWM with LED example.

 * Output PWM waves on LEDs to make them fade in and out.

 *

 * \return Unused (ANSI-C compatibility).

 */

int main(void)

{

        /* Initialize the SAM system */

        sysclk_init();

        board_init();



        /* Configure the console uart for debug information */

        configure_console();



        /* Output example information */

        puts(STRING_HEADER);



        /* Enable PWM peripheral clock */

        pmc_enable_periph_clk(ID_PWM);



        /* Disable PWM channels for LEDs */

        pwm_channel_disable(PWM, PIN_PWM_LED0_CHANNEL);

        pwm_channel_disable(PWM, PIN_PWM_LED1_CHANNEL);



        /* Set PWM clock A as PWM_FREQUENCY*PERIOD_VALUE (clock B is not used) */

        pwm_clock_t clock_setting = {

                .ul_clka = PWM_FREQUENCY * PERIOD_VALUE,

                .ul_clkb = 0,

                .ul_mck = sysclk_get_cpu_hz()

        };

        pwm_init(PWM, &clock_setting);



        /* Initialize PWM channel for LED0 */

        /* Period is left-aligned */

        g_pwm_channel_led.alignment = PWM_ALIGN_LEFT;

        /* Output waveform starts at a low level */

        g_pwm_channel_led.polarity = PWM_LOW;

        /* Use PWM clock A as source clock */

        g_pwm_channel_led.ul_prescaler = PWM_CMR_CPRE_CLKA;

        /* Period value of output waveform */

        g_pwm_channel_led.ul_period = PERIOD_VALUE;

        /* Duty cycle value of output waveform */

        g_pwm_channel_led.ul_duty = INIT_DUTY_VALUE;

        g_pwm_channel_led.channel = PIN_PWM_LED0_CHANNEL;

        pwm_channel_init(PWM, &g_pwm_channel_led);



        /* Enable channel counter event interrupt */

        pwm_channel_enable_interrupt(PWM, PIN_PWM_LED0_CHANNEL, 0);



        /* Initialize PWM channel for LED1 */

        /* Period is center-aligned */

        g_pwm_channel_led.alignment = PWM_ALIGN_CENTER;

        /* Output waveform starts at a high level */

        g_pwm_channel_led.polarity = PWM_HIGH;        

        /* Period is left-aligned */

        g_pwm_channel_led.ul_prescaler = PWM_CMR_CPRE_CLKA;

        /* Period value of output waveform */

        g_pwm_channel_led.ul_period = PERIOD_VALUE;

        /* Duty cycle value of output waveform */

        g_pwm_channel_led.ul_duty = INIT_DUTY_VALUE;

        g_pwm_channel_led.channel = PIN_PWM_LED1_CHANNEL;

        pwm_channel_init(PWM, &g_pwm_channel_led);



        /* Disable channel counter event interrupt */

        pwm_channel_disable_interrupt(PWM, PIN_PWM_LED1_CHANNEL, 0);









    

        

        /* Configure interrupt and enable PWM interrupt */

        NVIC_DisableIRQ(PWM_IRQn);

        NVIC_ClearPendingIRQ(PWM_IRQn);

        NVIC_SetPriority(PWM_IRQn, 0);

        NVIC_EnableIRQ(PWM_IRQn);



        /* Enable PWM channels for LEDs */

        pwm_channel_enable(PWM, PIN_PWM_LED0_CHANNEL);

        pwm_channel_enable(PWM, PIN_PWM_LED1_CHANNEL);





  

    ioport_set_pin_level(LED2_GPIO, IOPORT_PIN_LEVEL_LOW);

        ioport_set_pin_level(LED3_GPIO, IOPORT_PIN_LEVEL_LOW);



        /* Infinite loop */

        while (1) {

                

                

                

                

                

        }

}

经测试，两个LED,渐明渐暗。