The USB peripheral registers can be divided into the following groups:
• Common Registers: Interrupt and Control registers
• Endpoint Registers: Endpoint configuration and status
• Buffer Descriptor Table: Location of packet memory used to locate data buffers
All register addresses are expressed as offsets with respect to the USB peripheral registers base address 0x4000 5C00, except the buffer descriptor table locations, which starts at the address specified by the USB_BTABLE register. Due to the common limitation of APB1 bridges on word addressability, all register addresses are aligned to 32-bit word boundaries although they are 16-bit wide. The same address alignment is used to access packet buffer memory locations, which are located starting from 0x4000 6000.
• Base address: 0x40005C00
• USB_BTABLE(Buffer Descriptor Table): 0x50
• Packet Buffer: 0x40006000