Solved
STM32L053DISCO - How to enable 3V_O or 5V_O
In the document UM1775 there is stated the following:
"5 V and 3 V can be used as output power supplies when an extension board is
connected to pins P2 and P3.
...
In this case, the 5V_O and 3V_O pins deliver a 5 V or 3.3 V power supply and the
power consumption of the extension board must be lower than 100 mA."
Yet, the Supply for 3V_O is gated through T2 which in turn is controlled by PB15 on the SM32F103 (PWR_ENn); I guess that this is the controller which handles the ST-Link and cannot be changed.
How does this controller determine if there is an extension board connected to P2 or P3 so that it enables that supply?
