I am working on an STM32f401 Nucleo board(STM32f401 datasheet for reference: http://www.kynix.com/uploadfiles/pdf65976/STM32F401CCU6.pdf) and ESP8266-01 wifi module. I am using Eclipse gcc-arm tool chain and cubeMx to generate code. I can transfer and receive data perfectly with USART/UART DMA. Now ...