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STM32F405 UART CTS RTS flow control issue

Question asked by Deep Gadhia on Dec 14, 2017



We are using STM32F405 controller with CUBE MX library for UART communication with hardware flow control. Our aim is to wakeUp STM board from STOP mode when UART data comes. So I monitor RTS and CTS lines and connect them to interrupt pin. So that it will wake up host device.


When sending data from Other peripheral to STM32 host controller, STM32F4 RTS line give pulse otherwise it will be logic level 0 and also CTS line will remain Logic level 0 of STM32. If I send data from host STM32F4 controller it will not generate any signal on CTS or RTS line. It looks I am missing something. Communication is correct and verified on both end but logic level of CTS and RTS do not behave correct.


Also I have read some article about CTS and RTS of UART that suggest its logic level should be 1 when configure but here I found it remain 0. Please help us on this behaviour of STM32f4 UART.