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STM32 Nucleo F411RE: power up issue with USB battery

Question asked by Robert Kwan on Feb 28, 2017
Latest reply on Mar 6, 2017 by Robert Kwan



I am encountering problem that the USB battery cannot power up the STM32 Nucleo F411RE 

after I enabled the UART communication with ESP8266 Nodemcu.


I can have the PC USB working ok and see the UART communication from the COM port on PC.


However, after I replace the PC USB with the USB battery on either the STM32 Nucleo F411RE or the ESP8266 Nodemcu, I would not see any UART communication at all via the COM port.


My USB battery is already with output 5V 1000mA and it is able to drive either the Nucleo board or the ESP8266 Nodemcu before I used the UART communication between them and so I can tell that it's somehow related the UART communication enabled.  But I can't understand why UART would make such a difference?!  My UART setup is primitive and so no sleep mode is used yet.


I even tried directly with USB Wall Charger but I still could not see any UART communication from the COM port then.

Therefore, I doubt if it would help even if I buy new 2000mA USB battery?!


I checked from the other post that this may help:- 


But since I have no experience on this, I would like to see if anyone would have similar experience first please.



Thanks & Best Regards,