I am working on connecting a ESP8266-01 WiFi chip to the STM32F769NI-DISCO board. I have enabled UART5 in STM32CUBE and put EXT_SCL, EXT_RST and EXT_SDA into high impedance mode by putting them as inputs with NOPULL (as per the user manual: page 20). Once I connect the boards, I get a Fault Power error with LED LD7 blinking. I have root caused this to Pin 6 (CH_PD/EXT_RST). The Fault Power does not show if that wire is not connected.