1、硬件连接
2、PWM通道
可以看出，PC6对应的是TIME2的CH0通道。
3、实现方法
通过调节占空比，递增占空比，led逐渐变亮，视觉上是呼吸灯的效果。
4、核心代码
（1）pwm初始化
代码语言：javascript复制void PwmInit(void)
{
rcu_periph_clock_enable(RCU_GPIOC);
/* TIMER1 GPIO */
gpio_mode_set(GPIOC, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO_PIN_6 );
gpio_output_options_set(GPIOC, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, GPIO_PIN_6);
gpio_af_set(GPIOC, GPIO_AF_1, GPIO_PIN_6);
//64000000/6400=10k
//TIMER2CLK = SystemCoreClock/6400 = 0.01MHz, the period is 1s(100/10000).=0.01s=10ms=100hz
timer_oc_parameter_struct timer_ocinitpara;
timer_parameter_struct timer_initpara;
/* enable the peripherals clock */
rcu_periph_clock_enable(RCU_TIMER2);
/* deinit a TIMER */
timer_deinit(TIMER2);
/* initialize TIMER init parameter struct */
timer_struct_para_init(&timer_initpara);
/* TIMER2 configuration */
timer_initpara.prescaler = 6399;
timer_initpara.alignedmode = TIMER_COUNTER_EDGE;
timer_initpara.counterdirection = TIMER_COUNTER_UP;
timer_initpara.period = 99;
timer_initpara.clockdivision = TIMER_CKDIV_DIV1;
timer_init(TIMER2, &timer_initpara);
/* initialize TIMER channel output parameter struct */
timer_channel_output_struct_para_init(&timer_ocinitpara);
/* configure TIMER channel output function */
timer_ocinitpara.outputstate = TIMER_CCX_ENABLE;
timer_ocinitpara.ocpolarity = TIMER_OC_POLARITY_HIGH;
timer_channel_output_config(TIMER2, TIMER_CH_0, &timer_ocinitpara);
timer_channel_output_pulse_value_config(TIMER2, TIMER_CH_0, 99);
/* CH0 configuration in OC timing mode */
timer_channel_output_mode_config(TIMER2, TIMER_CH_0, TIMER_OC_MODE_PWM0);
/* enable a TIMER */
timer_enable(TIMER2);
}
（2）更改占空比
代码语言：javascript复制void PwmOut(void)
{
static uint32_t tick=0;
static uint8_t out=1;
if(SystemGetTick()-tick>200)
{
tick=SystemGetTick();
out=out 10;
if(out>100)
{
out=1;
}
timer_channel_output_pulse_value_config(TIMER2, TIMER_CH_0, out-1);
}
}
5、现象
6、示波器测量波形
