USB Peripheral Interface

Github: http://github.com/ultraembedded/cores

This component is a simple USB Peripheral Interface (Device) implementation with an AXI4-Lite slave register interface, and with a UTMI interface for connection to a USB PHY.

It has been designed to support USB2.0, but currently has been only tested in Full Speed peripheral mode (12Mbit/s).

Features

• USB 2.0 Device mode support.
• Simple register data read/write interface (low performance / not DMA based).
• UTMI PHY interface (see my UTMI to ULPI Conversion wrapper project to allow connection to a ULPI PHY e.g. USB3300)
• Current build configuration has 4 endpoints

Limitations

• Only tested for USB-FS (Full Speed / 12Mbit/s) only.
• AXI4-L address and data must arrive in the same cycle.

Software

Provided with a USB-CDC test stack (USB Serial port) with loopback/echo example.

To make this functional on your platform;

• Set USB_DEV_BASE to the correct address for the peripheral.
• Implement the millisecond timer functions in timer.h.
• Change USB_BYTE_SWAP16 in usbf_defs.h if your CPU is big endian.

Testing

Verified under simulation then tested on FPGA as a USB-CDC mode peripheral (USB serial port) against Linux & Windows PCs.

References

• USB 2.0 Specification
• UTMI Specification
• USB Made Simple
• UTMI to ULPI Conversion

Register Map

Offset	Name	Description
0x00	USB_FUNC_CTRL	[RW] Control Register
0x04	USB_FUNC_STAT	[RW] Status Register
0x08	USB_FUNC_ADDR	[RW] Address Register
0x0c	USB_EP0_CFG	[RW] Endpoint 0 Configuration
0x10	USB_EP0_TX_CTRL	[RW] Endpoint 0 Tx Control
0x14	USB_EP0_RX_CTRL	[W] Endpoint 0 Rx Control
0x18	USB_EP0_STS	[R] Endpoint 0 status
0x1c	USB_EP0_DATA	[RW] Endpoint Data FIFO
0x20	USB_EP1_CFG	[RW] Endpoint 1 Configuration
0x24	USB_EP1_TX_CTRL	[RW] Endpoint 1 Tx Control
0x28	USB_EP1_RX_CTRL	[W] Endpoint 1 Rx Control
0x2c	USB_EP1_STS	[R] Endpoint 1 status
0x30	USB_EP1_DATA	[RW] Endpoint Data FIFO
0x34	USB_EP2_CFG	[RW] Endpoint 2 Configuration
0x38	USB_EP2_TX_CTRL	[RW] Endpoint 2 Tx Control
0x3c	USB_EP2_RX_CTRL	[W] Endpoint 2 Rx Control
0x40	USB_EP2_STS	[R] Endpoint 2 status
0x44	USB_EP2_DATA	[RW] Endpoint Data FIFO
0x48	USB_EP3_CFG	[RW] Endpoint 3 Configuration
0x4c	USB_EP3_TX_CTRL	[RW] Endpoint 3 Tx Control
0x50	USB_EP3_RX_CTRL	[W] Endpoint 3 Rx Control
0x54	USB_EP3_STS	[R] Endpoint 3 status
0x58	USB_EP3_DATA	[RW] Endpoint Data FIFO

Register: USB_FUNC_CTRL

Bits	Name	Description
8	HS_CHIRP_EN	High-speed Chirp Enable
7	PHY_DMPULLDOWN	UTMI PHY D+ Pulldown Enable
6	PHY_DPPULLDOWN	UTMI PHY D+ Pulldown Enable
5	PHY_TERMSELECT	UTMI PHY Termination Select
4:3	PHY_XCVRSELECT	UTMI PHY Transceiver Select
2:1	PHY_OPMODE	UTMI PHY Output Mode
0	INT_EN_SOF	Interrupt enable - SOF reception

Register: USB_FUNC_STAT

Bits	Name	Description
13	RST	USB Reset Detected (cleared on write)
12:11	LINESTATE	USB line state (bit 1 = D+, bit 0 = D-)
10:0	FRAME	Frame number

Register: USB_FUNC_ADDR

Bits	Name	Description
6:0	DEV_ADDR	Device address

Register: USB_EPx_CFG

Bits	Name	Description
3	INT_RX	Interrupt on Rx ready
2	INT_TX	Interrupt on Tx complete
1	STALL_EP	Stall endpoint
0	ISO	Isochronous endpoint

Register: USB_EPx_TX_CTRL

Bits	Name	Description
17	TX_FLUSH	Invalidate Tx buffer
16	TX_START	Transmit start - enable transmit of endpoint data
10:0	TX_LEN	Transmit length

Register: USB_EPx_RX_CTRL

Bits	Name	Description
1	RX_FLUSH	Invalidate Rx buffer
0	RX_ACCEPT	Receive data accepted (read)

Register: USB_EPx_STS

Bits	Name	Description
20	TX_ERR	Transmit error (buffer underrun)
19	TX_BUSY	Transmit busy (active)
18	RX_ERR	Receive error - CRC mismatch or buffer overflow
17	RX_SETUP	SETUP request received
16	RX_READY	Receive ready (data available)
10:0	RX_COUNT	Endpoint received length (RD)

Register: USB_EPx_DATA

Bits	Name	Description
7:0	DATA	Read or write from Rx or Tx endpoint FIFO