Main ComponentsTransmitting/Receiving Nodes:

Four Xilinx Spartan IIE FPGAs

Serializer/Deserializers: Four National DS92LV16’s

LVDS Crossbar:One National SCAN90CP02

Power Supply:+12V Power InputTwelve Datel LSN DC/DC ConvertersVarious Decoupling Capacitors

SolutionLow Voltage Differential Signaling (LVDS)A widely recognized standard which uses differential current direction to represent logic levels. This allows very high speed serial data to be sent through two 100 ohm matched impedance traces, using approx. 8 times less space than parallel signaling.

PurposeGoal:

Provide a proof of concept design and documentation that highlight the benefits of using a low-voltage differential serial communications scheme rather than standard single-ended parallel interconnect.

Specifications:•Transfer data at a speed of 800 Mbps from either of two transmitting nodes to either of two receiving nodes

•Show the stability of the system with a Bit Error Rate Test giving no errors in a 15 minute period.

•Deliver documentation comparing serial differential signaling and parallel single-ended signaling on the basis of power consumption and circuit board area.

Reconfigurable Computing for SpaceChris Canine, Cameron Dennis, Terseer Ityavyar

Sponsored by Dr. Greg Donohoe, NASA, University of Idaho CAMBR

The ProductPCB SpecificationsSize: 12” W x 10.5” HLayers: Six w/ two planesSmallest Trace: 7 microns# of Components: 398

DC/DC ConvertersProvide efficient, point of use power conversion from +12V to required voltage. Includes enable and trim.

DC/DC ConvertersProvide efficient, point of use power conversion from +12V to required voltage. Includes enable and trim.

LVDS CrossbarRetransmits incoming data to receiving FPGAs. Can act as splitter, repeater or crossover as needed.

LVDS CrossbarRetransmits incoming data to receiving FPGAs. Can act as splitter, repeater or crossover as needed.

Spartan IIE FPGAsGenerate the semi-random data used during the BERT and control the sending and receiving of data.

Spartan IIE FPGAsGenerate the semi-random data used during the BERT and control the sending and receiving of data.

LCD Display ScreenAllows the board to display the number of errors during the Bit Error Rate Test, or other information needed.

LCD Display ScreenAllows the board to display the number of errors during the Bit Error Rate Test, or other information needed.

Decoupling CapacitorsProvide quick, temporary energy during high power demand. Reduces effects of under-voltage situations.

Decoupling CapacitorsProvide quick, temporary energy during high power demand. Reduces effects of under-voltage situations.

Serializer/DeserializerSerializes 16-bit parallel data and clock into a serial stream at 1.25Gbps. Also recovers data at receiver.

Serializer/DeserializerSerializes 16-bit parallel data and clock into a serial stream at 1.25Gbps. Also recovers data at receiver.

3.5mA

3.5mA

Tx Rx+

350mV

-

Basic LVDS communication

Pros• 350mV switching results in fewer power losses• Differential design creates little noise and rejects

outside interference• Uses only two lines, no matter what the data transfer rate is

Cons• Matched impedance lines are more difficult to lay out when creating PCB• Requires that the components used support the

standard and may require component changes

The team would like to thank the followingpeople for their contributions and help:

Dr. Joe Law, Dr. Herb Hess, Greg Klemesrud and John Geidl