STM32 prototype unable to connect to PC using ST-Link/V2 SWD
You must separate pin VDDA (analog) from pins VDD (digital). You need to use L (inductor or SMD ferrite bead) and C (capacitor) between VDDA and VDD pins. Capacitor must be as close as possible to pin VDDA. Or use second LDO for only VDDA and VSSA pins.