12V Power Adapter - Everything will be powered using a 12V 5A power adapter.
12V - The whole system will receive 12V, but the only system that's using the full 12V directly is the motor and motor controller.
DC/DC Converter: 5V - The 5V will be generated by a DC/DC converter. It will power the components in the system such as the ultrasonic sensors and the STM32F746ZG.
DC/DC Converter: 3.3V - The 3.3V will be generated by a DC/DC converter. It will provide 3.3V to the STM32F746ZG VDD pins.
The power system was designed by me. I created the schematics and PCB layout in KiCAD.
12V
The power adapter I can get off ebay that supplies 12V, 5A. The motor itself will be powered at 12V. The 12V goes into the A4988 motor controller at the motor supply input across a 100uF capacitor. The windings of the motor are connected to the A1,B1,A2,B2 pins of the A4988, which power the motor. The DC/DC converters will receive the 12V to convert down to usable levels for the other components.
DC/DC Converter: 5V
The 5V will be generated by using the XL1509, a step down DC/DC converter that can drive up to a 2A load. It will take a 12V input. I have a fuse at the input for protection and a ferrite bead for filtering. The other parts are picked based off the datasheet. The 5V output will power the ultrasonic sensors, the audio amplifier, the logic level for the A4988, the bluetooth, and the hall sensors.
DC/DC Converter: 3.3V
The 3.3V will be generated by using another XL1509. This 3.3V is for the STM32F746ZG. It will have either a 12V input from the adapter or a 5V input from a USB source. The use of a FET and a zener I used essentially creates a OR gate and so the XL1509 can receive power from one or the other input. Since I will have to connect a USB to program the STM32, it should be powered by the USB during this. I have a fuse at the input for protection and a ferrite bead for filtering. The other parts are picked based off the datasheet.