基于PWM外设轮询模式编写呼吸灯程序

软件实现 软件代码见 examples/pwm/pwm_breath_led #define BSP_PWM_CLOCK_SOURCE ROOT_CLOCK_SOURCE_XCLK#define BSP_PWM_CLOCK_DIV 1 配置 PWM 设备时钟源，见 bsp/board/bl706_iot/clock_config . h #define CONFIG_GPIO22_FUNC GPIO_FUN_PWM 配置 PWM 设备复用引脚，见 bsp/board/bl706_iot/pinmux_config . h #define BSP_USING_PWM_CH2 #if defined ( BSP_USING_PWM_CH2)#ifndef PWM_CH2_CONFIG#define PWM_CH2_CONFIG \{ \ . ch = 2, \ . frequency = 1000000, \ . dutycycle = 0, \ . it_pulse_count = 0, \}#endif#endif 使能 BSP_USING_PWM_CH2 并配置 PWM 设备配置，见 bsp/board/bl706_iot/peripheral_config . h pwm_register( PWM_CH2_INDEX, " led_breath " ) ; struct device *led_breath = device_find ( " led_breath " ) ; if ( led_breath ) { PWM_DEV( led_breath ) - >period = 32; //frequence = 32M/1/32 = 1Mhz PWM_DEV( led_breath ) - >threshold_low = 16; PWM_DEV( led_breath ) - >threshold_high = 32; device_open ( led_breath, DEVICE_OF LAG_STREAM_TX) ; pwm_channel_start ( led_breath ) ; } 首先调用 pwm_register 函数注册 PWM 设备的一个通道，当前注册 PWM_CH2 然后通过 find 函数找到设备对应的句柄，保存于 led_breath 句柄中 设置 PWM_CH2 的频率为 1Mhz，占空比为 50% 使用 device_open 以轮询模式来打开 led_breath 设备 for ( pwm_cfg . threshold_high = 0; pwm_cfg . threshold_high <= 32; pwm_cfg . threshold_high++) { device_control ( led_breath, DEVICE_CTRL_PWM_DUTYCYCLE_CONFIG, &pwm_cfg) ; bflb_platform_delay_ms ( 50) ; } for ( pwm_cfg . threshold_high = 32; 0 <= pwm_cfg . threshold_high && pwm_cfg . threshold_high <= 32; pwm_cfg . threshold_high - - ) { device_control ( led_breath, DEVICE_CTRL_PWM_DUTYCYCLE_CONFIG, &pwm_cfg) ; bflb_platform_delay_ms ( 50) ; } 使用 device_contorl 函数，配合 DEVICE_CTRL_PWM_DUTYCYCLE_CONFIG 指令，可以修改当前 PWM 通道的占空 比。 详情请下载~~~