Digilent Atlys Manuale di riferimento - Pagina 2

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Atlys Reference Manual

Configuration

After power-on, the

FPGA on the Atlys

board must be

configured (or

programmed) before it

can perform any

functions. The FPGA

can be configured in

one of three ways: a

USB-connected PC can

configure the board

using the JTAG port any

time power is on, a

configuration file stored

in the SPI Flash ROM

can be automatically

transferred to the FPGA

at power-on, or a

programming file can be transferred from a USB memory stick

attached to the USB HID port.

An on-board "mode" jumper (JP11) selects between JTAG/USB

and ROM programming modes. If JP11 is not loaded, the FPGA will

automatically configure itself from the ROM. If JP11 is loaded, the

FPGA will remain idle after power-on until configured from the

JTAG or Serial programming port.

Both Digilent and Xilinx freely distribute software that can be used

to program the FPGA and the SPI ROM. Programming files are

stored within the FPGA in SRAM-based memory cells. This data

defines the FPGA's logic functions and circuit connections, and it

remains valid until it is erased by removing power or asserting the

PROG_B input, or until it is overwritten by a new configuration file.

FPGA configuration files transferred via the JTAG port use the .bin

or .svf file types, files transferred from a USB stick use the .bit file

type, and SPI programming files can use .bit, .bin, or .mcs types.

The ISE/WebPack or EDK software from Xilinx can create bit, svf,

bin, or mcs files from VHDL, Verilog, or schematic-based source

files (EDK is used for MicroBlaze™ embedded processor-based

designs). Digilent's Adept software or Xilinx's iMPACT software can

be used to program the FPGA or ROM using the Adept USB port.

During FPGA programming, a .bit or .svf file is transferred from the

PC directly to the FPGA using the USB-JTAG port. When

programming the ROM, a .bit, .bin, or .mcs file is transferred to the ROM in a two-step process. First,

the FPGA is programmed with a circuit that can program the SPI ROM, and then data is transferred to

the ROM via the FPGA circuit (this complexity is hidden from the user – a simple "program ROM"

interface is presented by the programming software). After the ROM has been programmed, it can

automatically configure the FPGA at a subsequent power-on or reset event if the JP11 jumper is

Doc: 502-178

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