STM32F4 Discovery 官方板子配套示例 外设示例: ADC3_DMA ADC_Interleaved_DMAmode2 DAC_SignalsGeneration DMA_FLASH_RAM EXTI FLASH_Program FLASH_Write_Protection IO_Toggle IWDG MEMS PWR_CurrentConsumption PWR_STANDBY PWR_STOP RCC SysTick TIM_ComplementarySignals TIM_PWM_Input TIM_PWM_Output TIM_TimeBase