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USB 1.1 Host Controller

This IP core is a cutdown USB host controller which allows communications with full-speed (12mbps) USB devices.

The IP is accessed via an AXI4-Lite slave register interface for control, status and data.

Data to be sent or received is stored in some internal FIFOs. The data is accessed through the AXI4-Lite slave port. There is no DMA engine (e.g. a bus mastering interface) associated with this IP.

The core functions well, is very small, but is fairly inefficient in terms of CPU cycles required to perform USB transfers. This core is not compliant with any standard USB host interface specification, e.g OHCI or EHCI.

Instantiation

Instance usbh_host and hookup to UTMI PHY interface and a AXI4-Lite master (e.g. from your CPU). The core requires a 48MHz/60MHz clock input, which the AXI4-Lite and UTMI interfaces are expected to be synchronous to.

Limitations
  • Only tested for USB-FS (Full Speed / 12Mbit/s) only.
Testing

Verified under simulation and on FPGA with various USB devices attached (hubs, mass storage, network devices).

References
Configuration
  • USB_CLK_FREQ - Core clock frequency (supports: 60000000 or 48000000)
Size / Performance

With the default configuration...

  • the design contains 317 registers, 392 LUTs (Xilinx ISE - Spartan 6)
  • synthesizes to more than the required 48MHz on a Xilinx Spartan 6 LX9 (speed -3)
Register Map
Offset Name Description
0x00 USB_CTRL [RW] Control of USB reset, SOF and Tx FIFO flush
0x04 USB_STATUS [R] Line state, Rx error status and frame time
0x08 USB_IRQ_ACK [W] Acknowledge IRQ by setting relevant bit
0x0c USB_IRQ_STS [R] Interrupt status
0x10 USB_IRQ_MASK [RW] Interrupt mask
0x14 USB_XFER_DATA [RW] Tx payload transfer length
0x18 USB_XFER_TOKEN [RW] Transfer control info (direction, type)
0x1c USB_RX_STAT [R] Transfer status (Rx length, error, idle)
0x20 USB_WR_DATA [W] Tx FIFO address for write data
0x20 USB_RD_DATA [R] Tx FIFO address for read data
Register: USB_CTRL
Bits Name Description
8 TX_FLUSH Flush Tx FIFO
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 ENABLE_SOF Enable SOF (start of frame) packet generation
Register: USB_STATUS
Bits Name Description
31:16 SOF_TIME Current frame time (0 - 48000)
2 RX_ERROR Rx error detected (UTMI). Clear on new xfer.
1:0 LINESTATE_BITS Line state (1 = D-, 0 = D+)
Register: USB_IRQ_ACK
Bits Name Description
3 DEVICE_DETECT Interrupt on device detect (linestate != SE0).
2 ERR Interrupt on error conditions.
1 DONE Interrupt on transfer completion.
0 SOF Interrupt on start of frame.
Register: USB_IRQ_STS
Bits Name Description
3 DEVICE_DETECT Interrupt on device detect (linestate != SE0).
2 ERR Interrupt on error conditions.
1 DONE Interrupt on transfer completion.
0 SOF Interrupt on start of frame.
Register: USB_IRQ_MASK
Bits Name Description
3 DEVICE_DETECT Interrupt on device detect (linestate != SE0).
2 ERR Interrupt on error conditions.
1 DONE Interrupt on transfer completion.
0 SOF Interrupt on start of frame.
Register: USB_XFER_DATA
Bits Name Description
15:0 TX_LEN Tx transfer data length
Register: USB_XFER_TOKEN
Bits Name Description
31 START Transfer start request
30 IN IN transfer (1) or OUT transfer (0)
29 ACK Send ACK in response to IN data
28 PID_DATAX DATA1 (1) or DATA0 (0)
23:16 PID_BITS Token PID (SETUP=0x2d, OUT=0xE1 or IN=0x69)
15:9 DEV_ADDR Device address
8:5 EP_ADDR Endpoint address
Register: USB_RX_STAT
Bits Name Description
31 START_PEND Transfer start pending
30 CRC_ERR CRC error detected
29 RESP_TIMEOUT Response timeout detected (no response)
28 IDLE SIE idle
23:16 RESP_BITS Received response PID
15:0 COUNT_BITS Received data count
Register: USB_WR_DATA
Bits Name Description
7:0 DATA Date byte
Register: USB_RD_DATA
Bits Name Description
7:0 DATA Date byte

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