demo

本 Demo 实现了通过 PWM 来控制背光的亮度：

void turn_on_lcd_backlight(void)
{
    struct rt_device_pwm *pwm_dev;

    /* turn on the LCD backlight */
    pwm_dev = (struct rt_device_pwm *)rt_device_find("pwm");
    /* pwm frequency:100K = 10000ns */
    rt_pwm_set(pwm_dev, LCD_PWM_DEV_CHANNEL, 10000, 10000);
    rt_pwm_enable(pwm_dev, LCD_PWM_DEV_CHANNEL);
}