NB2DSK01 - NanoBoard-PC Interface (USB Port)

The NB2DSK01 can be connected to your PC via one of the computer's standard USB 2.0 ports. The NB2DSK01 provides a corresponding port through use of a USB B-type connector.

Figure 1. USB interface port for
connection to a PC.

Providing the high-speed interface between the NanoTalk Controller and the USB bus is an EZ-USB SX2™ device (CY7C68001-56LFC, from Cypress Semiconductor). This device has a built-in USB transceiver and a Serial Interface Engine (SIE), which automatically manages the USB protocol. The device is powered by the NB2DSK01's 3.3V supply and is configured to provide a 16-bit bidirectional data bus to/from the NanoTalk Controller.

Internal clocking for the USB transceiver (and various internal logic) is supplied from an internal PLL, which itself is driven by an external 24MHz crystal connected across the device's XTALIN and XTALOUT pins.

Reset of the USB interface device is provided through use of a supervisory reset circuit device – a MAX6315US26D1, from Maxim. This device will assert the reset signal to the CY7C68001 (active Low) if its 3.3V supply voltage dips below 2.3V, or if it receives an external reset signal from the NanoTalk Controller. The reset signal will remain asserted for a minimum of 1ms (typically 1.4ms) after the supply voltage rises above this threshold, and/or the NanoTalk Controller deasserts its reset signal.

The USB data lines (D+, D-) are protected against high transient voltages through the use of a low-capacitance transient voltage suppressor device – a NUP2201MR6, from ON Semiconductor.
 

 
When you launch Altium Designer, the system loads a driver that configures the USB port to run as a single multiplexed JTAG link between the NB2DSK01 and the PC. Three distinct JTAG chains present on the NB2DSK01 constitute this multiplexed link (NanoBoard JTAG chain, Hard Devices JTAG chain, Soft (Nexus) Devices JTAG chain), the multiplexing being handled by the NanoTalk Controller. Demultiplexing of the link is performed at the PC end, by the Altium Designer software.

Location on Board

The USB connector (designated J4) is located on the component side of the board, to the right of the CAN port.

The CY7C68001 device (designated U52) and the NUP2201MR6 device (designated U51) are also located on the component side of the board, directly below the USB port itself.

Figure 2. USB high-speed interface device (U52)
and voltage suppressor (U51).

The MAX6315 device (designated U50) is located on the solder side of the board.

Schematic Reference

The USB circuitry can be found on the following sheets of the motherboard schematics:

• Sheet 22 (USB_CY7C68001-56LFC.SchDoc, entitled High-Speed USB 2.0 Controller)

• Sheet 23 (CON_USBB_RA.SchDoc, entitled USB 2.0 Type B Connector).

Further Device Information

For more information on the CY7C68001 device, refer to the datasheet (CY7C68001.pdf) available at www.cypress.com.

For more information on the MAX6315 device, refer to the datasheet (MAX6315.pdf) available at www.maxim-ic.com.

For more information on the NUP2201MR6 device, refer to the datasheet (NUP2201MR6-D.pdf) available at www.onsemi.com.

See Also