Can the BT_CFG pin be used as a GPIO after booting from an eMMC or SD card? In that case, at what timing should the register assigned to BT_CFG be rewritten?
Yes, BT_CFG pin can be used as GPIO after booting from an eMMC or SD card. For details, please refer to the chapter 8.2.2 'High-level boot sequence" in Reference Manual.
