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Powering Nucleo-F042K6 from external +5V

Question asked by Jerome Chapdelaine on Sep 7, 2017
Latest reply on Sep 8, 2017 by Jerome Chapdelaine


I am trying to power a Nucleo-F042K6 from the external +5V only, i.e. without USB connected since my code is completed and fully functionnal. According to the user manual this shoud be possible and the only limitation is that the ST-LINK must be connected after.


However the F042K6 will not start because its NRST is kept low (at arount 1.2V),  probably clamped by the protection diodes of the ST-LINK which does not have any power.  


I suppose I could remove SB9 but then I'm afraid of losing some ST-LINK capabilities if I want to re-flash my code.


Am I missing something in the user manual?  SB9 is only mentioned if we want to power the board with 3.3V.


Thanks to all.