USB 2.0 Controller

LimeSDR XTRX may be powered and programmed via USB 2.0, by connecting it to a Micro-B port or Mini PCIe connector.

Note

Data transfer via USB 2.0 interface requires custom gateware.

USB 2.0 is implemented using Microchip USB3333E-GL transceiver. The controller signals description are shown below:

• USB_D[7:0] – 8-bit data interface is connected to FPGA.

• USB_NRST, USB_NXT, USB_DIR, USB_STP – interface control signals.

• USB_CLK – interface clock. Clock from transceiver is fed to XILINX FPGA.

• USB_26M – interface clock. Clock from FPGA is fed to Lime transceiver.

USB 2.0 controller pins, schematic signal names, FPGA interconnections and I/O standard are described in Table 9.

Table 9. USB 2.0 controller interface

Chip pin (IC19)	Chip reference (IC19)	Schematic signal name	FPGA pin	I/O standard
C2	RESETB	USB_NRST	M18	3.3V
E3	DAT7	USB_D7	C15	3.3V
E4	DAT6	USB_D6	A14	3.3V
E5	DAT5	USB_D5	A15	3.3V
D4	DAT4	USB_D4	B15	3.3V
D5	DAT3	USB_D3	A16	3.3V
C4	DAT2	USB_D2	B16	3.3V
C5	DAT1	USB_D1	A17	3.3V
B4	DAT0	USB_D0	B17	3.3V
A3	STP	USB_STP	C17	3.3V
B5	NXT	USB_NXT	A18	3.3V
A4	DIR	USB_DIR	B18	3.3V
A5	CLKOUT	USB_CLK	C16	3.3V
A2	REFCLK	USB_26M	E19	3.3V