Xilinx Virtex-6 Manual page 110

Chapter 4: About Design Elements
DNA_PORT
Primitive: Device DNA Data Access Port
Introduction
This element allows access to a dedicated shift register that can be loaded with the Device DNA data bits (unique
ID) for a given device. In addition to shifting out the DNA data bits, this component allows for the inclusion of
supplemental bits of your data, or allows for the DNA data to rollover (repeat DNA data after initial data has
been shifted out). This component is primarily used in conjunction with other circuitry to build added copy
protection for the FPGA bitstream from possible theft. Connect all inputs and outputs to the design to ensure
proper operation. To access the Device DNA data, you must first load the shift register by setting the active high
READ signal for one clock cycle. After the shift register is loaded, the data can be synchronously shifted out by
enabling the active high SHIFT input and capturing the data out the DOUT output port. Additional data can be
appended to the end of the 57-bit shift register by connecting the appropriate logic to the DIN port. If DNA
data rollover is desired, connect the DOUT port directly to the DIN port to allow for the same data to be shifted
out after completing the 57-bit shift operation. If no additional data is necessary, the DIN port can be tied to a
logic zero. The attribute SIM_DNA_VALUE can be optionally set to allow for simulation of a possible DNA data
sequence. By default, the Device DNA data bits are all zeros in the simulation model.
Port Descriptions
Port Direction
CLK Input
DIN Input
DOUT Output
READ Input
Input
SHIFT
Design Entry Method
Instantiation
Inference
CORE Generator™ and wizards
Macro support
Connect all inputs and outputs to the design to ensure proper operation.
110
Width Function
1
Clock input.
1
User data input pin.
1
DNA output data.
1
Active high load DNA, active low read input.
1
Active high shift enable input.
Recommended
No
No
No
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Virtex-6 Libraries Guide for HDL Designs
UG623 (v 14.5) March 20, 2013