I thought I had identified a problem but it turned out some more pins I thought were connected weren't actually connected to the st morpho connector due to the diagram on this page: https://developer.mbed.org/platforms/ST-Nucleo-F746ZG/ Unless you search for pins you want to use in this: http://www2.st.com/content/ccc/resource/technical/document/user_manual/group0/26/49/90/2e/33/0d/4a/da/DM00244518/files/DM00244518.pdf/jcr:content/translations/en.DM00244518.pdf You may get caught like I did and think it was fine to use PC_15, PC_14, and PH_0 out of the box without changing solder jumpers/etc. I would very much like to see asterisks placed next to all pins on the st morpho breakout diagram on this page: https://developer.mbed.org/platforms/ST-Nucleo-F746ZG/ to indicate that those pins are either already connected to something else, or will require a solder bridge to be added/removed to be used as gpio.

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