Obviously a copy-paste error.
This typos is raised internally.
We confirm that this line in the table 7 of UM1879 Rev 3 is not correct.
It will be corrected in next revision of the document as followed:
SB17, SB15 (MFX USART RX,TX)
PA2, PA3 of STM32F103CBT6 are not connected to MFX USART RX,TX
May I ask you to forward to the documentation team also my request to arrange in all DISCO UMs the pinout table in the way it is done now in the 'F4DISCO's UM1472rev.6, i.e. for each pin having listed its alternative functions (including analog and other non-matrix), pin number on the chip used on the DISCO, function on DISCO, position on any DISCO connector, and any SB or jumper relevant to that pin.
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