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

This component is a USB (CDC-ACM / USB Serial) to AXI4-Lite bus master bridge.
This IP enumerates as a full speed (12Mbit/s) USB device which can then be used to read / write to memories / peripherals in your FPGA based SoC.

The PHY / transceiver are built in requiring no additional external hardware other than a USB port connected to the FPGA I/Os.

This repo contains submodules, and to clone them run the following command;

git clone --recursive https://github.com/ultraembedded/core_usb_bridge.git

usb_bridge_top.v├── usb_bridge│   └── src_v│       ├── usb_bridge_fifo.v│       └── usb_bridge.v├── usb_cdc│   └── src_v│       ├── usb_cdc_core.v│       ├── usb_desc_rom.v│       ├── usbf_crc16.v│       ├── usbf_defs.v│       ├── usbf_device_core.v│       ├── usbf_sie_ep.v│       ├── usbf_sie_rx.v│       └── usbf_sie_tx.v└── usb_fs_phy    └── src_v        ├── usb_fs_phy.v        └── usb_transceiver.v

• Top: usb_bridge_top
• Clock: clk_i - 48MHz
• Reset: rst_i - Asynchronous, active high
• VID/PID can be changed in usb_desc_rom.v

Connection from your FPGA I/Os can be made simply using a breakout board;

• https://www.sparkfun.com/products/12035

In order to enumerate as a USB FS device, there must be a pull-up on the D+ pin (but not on the D- pin).
This can be achieved using the internal pull-ups on some FPGAs (though how reliable this is remains to be seen).

Example constraints (Xilinx Vivado);

set_property -dict { PACKAGE_PIN N4    IOSTANDARD LVCMOS33 } [get_ports { usb_dp_io }]; # USB D+set_property -dict { PACKAGE_PIN P3    IOSTANDARD LVCMOS33 } [get_ports { usb_dn_io }]; # USB D-set_property PULLUP TRUE [get_ports usb_dp_io]

For Xilinx FPGAs, pad pull-ups should be disabled before configuration is completed (PUDC_B).

Included python based utils provide peek and poke access, plus binary load / dump support.

Examples:

# Read a memory location (0x0)./sw/peek.py -d /dev/ttyACM0 -a 0x0# Write a memory word (0x0 = 0x12345678)./sw/poke.py -d /dev/ttyACM0 -a 0x0 -v 0x12345678

• USB Full Speed PHY
• USB CDC Device