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If the board does not appear to be working and the FPGA or voltage regulators are getting extremely hot it is likely that the FPGA has been destroyed. An
IC becoming too hot to touch is an indication of excessive current flow through the device, indicating that the FPGA or some other chip is shorted internally.
Your board is probably damaged beyond repair.
There are three likely causes of this kind of damage to the board:
The first is electrostatic discharge (ESD) damage to the I/O buffers on the FPGA. All electronic devices built using MOSFET transistors are susceptible to ESD
damage. The gate insulation layer on a MOSFET transistor is extremely thin and the high voltage associated with static charge can easily produce an arc across the gate, destroying the transistor. Xilinx devices have some internal ESD protection and Digilent places external ESD protection diodes on many of the I/O pins, but these can't always provide absolute protection. ESD safe-handling procedures should always be used when handling boards with MOSFET devices.
A second possible cause of damage to our boards is logic-level conflicts between pins on the FPGA or pins on other devices on the board or on peripheral
devices. If two output pins are inadvertently connected and attempt to drive opposing logic levels (i.e., one output driving a logic high connected to another
output driving a logic low), excessive current will flow. By default, the output buffers on most Xilinx FPGA and CPLD devices can drive 24mA of current. This
level of current drive is necessary to produce very short rise and fall times on output signals. However, output buffers are not able to sustain this current flow
continuously and will overheat and be destroyed. A common failure when this occurs is a short between VCC and ground through the destroyed output buffer.
Because the I/O assignments on FPGA and CPLD devices are flexible, it is extremely important to avoid this problem by not making conflicting assignments of
output pins and ensuring that the logic design doesn't allow output drive conflicts to occur. To help reduce the likelihood of this kind of problem, Digilent places
current limiting resistors in series with many of the I/O signals on our boards, but this is not always possible, particularly for signals that are intended to allow
operation at very high speeds.
The third possible cause of damage is the inadvertent creation of short circuits between I/O pins while probing the board with test equipment. If an
oscilloscope, logic analyzer, or multimeter probe accidentally touches two I/O signals that happen to be driving opposite logic levels, this will produce the same
situation as described above. This short circuit will cause excessive current to flow through the output buffers, possibly destroying one or both of them.
With all Digilent system boards users must be very careful not to create situations leading to the above described problems. In general, if this happens, the
board is not repairable. We can not accept returns on boards that are out of warranty.
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If the board does not appear to be working and the FPGA or voltage regulators are getting extremely hot it is likely that the FPGA has been destroyed. An
IC becoming too hot to touch is an indication of excessive current flow through the device, indicating that the FPGA or some other chip is shorted internally.
Your board is probably damaged beyond repair.
There are three likely causes of this kind of damage to the board:
The first is electrostatic discharge (ESD) damage to the I/O buffers on the FPGA. All electronic devices built using MOSFET transistors are susceptible to ESD
damage. The gate insulation layer on a MOSFET transistor is extremely thin and the high voltage associated with static charge can easily produce an arc across the gate, destroying the transistor. Xilinx devices have some internal ESD protection and Digilent places external ESD protection diodes on many of the I/O pins, but these can't always provide absolute protection. ESD safe-handling procedures should always be used when handling boards with MOSFET devices.
A second possible cause of damage to our boards is logic-level conflicts between pins on the FPGA or pins on other devices on the board or on peripheral
devices. If two output pins are inadvertently connected and attempt to drive opposing logic levels (i.e., one output driving a logic high connected to another
output driving a logic low), excessive current will flow. By default, the output buffers on most Xilinx FPGA and CPLD devices can drive 24mA of current. This
level of current drive is necessary to produce very short rise and fall times on output signals. However, output buffers are not able to sustain this current flow
continuously and will overheat and be destroyed. A common failure when this occurs is a short between VCC and ground through the destroyed output buffer.
Because the I/O assignments on FPGA and CPLD devices are flexible, it is extremely important to avoid this problem by not making conflicting assignments of
output pins and ensuring that the logic design doesn't allow output drive conflicts to occur. To help reduce the likelihood of this kind of problem, Digilent places
current limiting resistors in series with many of the I/O signals on our boards, but this is not always possible, particularly for signals that are intended to allow
operation at very high speeds.
The third possible cause of damage is the inadvertent creation of short circuits between I/O pins while probing the board with test equipment. If an
oscilloscope, logic analyzer, or multimeter probe accidentally touches two I/O signals that happen to be driving opposite logic levels, this will produce the same
situation as described above. This short circuit will cause excessive current to flow through the output buffers, possibly destroying one or both of them.
With all Digilent system boards users must be very careful not to create situations leading to the above described problems. In general, if this happens, the
board is not repairable. We can not accept returns on boards that are out of warranty.
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When we designed the 40-pin interface between system boards and accessory boards we decided to number pins the same way on both system boards
and accessory boards. If the board is positioned so that the connector is facing up, pin 1 is the left-most, inner pin toward the center of the board. Pin 2 is the
left-most, outer pin toward the edge of the board, and so on. The odd-numbered pins are on the inner row and the even-numbered pins are on the outer row.
This pin numbering is the same on both system boards and accessory boards.
To connect an accessory board to a system board, the accessory board must be rotated relative to the system board to mate the connectors. The odd-
numbered pins on the accessory board will mate with the odd-numbered pins on the system board, and similarly for the even-numbered pins. However, pin 1
on the accessory board doesn't mate with pin 1 on the system board, it mates with pin 39. Pin 2 on the accessory board mates with pin 40 on the system
board, and so on.
An easy way to remember the pin mating is as follows: the system board pin number and accessory board pin number must add up to 40 for odd-numbered
pins and 42 for even-numbered pins. For example, pin 3 mates with pin 37 (3 + 37 = 40) and pin 4 mates with pin 38 (4 + 38 = 42).
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All Digilent Atmel AVR microcontroller-based embedded control boards require an appropriate power supply, a programming cable,
software development tools, and in-system programming software. The power supply and programming cable are not included with the board and must be
purchased in addition to the board.
The type of power supply to use depends on the intended application. Digilent has available wall-wart type power supplies and battery packs that are suitable
for use with our embedded control boards. The reference manual for each board specifies the safe input voltage range to be used with the voltage regulator
on the board.
There are many options for software development tools to use with Atmel AVR microcontrollers.
For assembly language development, Digilent recommends Atmel AVR Studio. This is a free software toolset that can be downloaded from the Atmel web site.
It includes an integrated development environment, assembler, debugger that supports debugging via simulation and the Atmel JTAG ICE-MKII, and in-system
programming support using the Atmel AVR-ISP In-System Programmer.
For C programming language development, Digilent recommends the WinAVR toolset. WinAVR is based on the GCC compiler tool chain and is free for download
here. The WinAVR toolset provides a GCC-based compiler, debugger, and in-system programming software. The latest version of Atmel AVR Studio also
includes support for WinAVR-based C projects.
Programming a completed design into the microcontroller on the board requires both in-system programming hardware and software. All Digilent AVR-based
embedded control boards are designed to work with Digilent JTAG-USB or JTAG USB-FS cables. Some boards, like the Cerebot, also support the Atmel AVR-ISP
In-System Programmer as well as the JTAG ICE-MKII. This is a hardware device that provides in-system debugging as well as in system programming capability.
Digilent provides free in-system programming software, the Digilent AVR Programmer, for use with our programming cables. This tool can be downloaded from
the Digilent web site. The Atmel AVR Studio application provides in-system programming support using the Atmel AVR-ISP or JTAG ICE-MKII. The WinAVR
toolset provides in-system programming software that supports the Atmel AVR-ISP.
There are various other third-party development and programming toolsets available, but Digilent is unable to provide recommendations or support for them.
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Digilent programmable logic boards ship with an appropriate power supply and programming cable, as needed. All Digilent
programmable logic boards feature programmable logic devices from Xilinx. Appropriate software is needed to develop logic designs to be loaded onto the
boards. Digilent does not produce the logic design and synthesis software. Xilinx has three options for design and synthesis software.
Xilinx ISE is a complete, full-featured, logic design environment. It supports both schematic entry and HDL entry of designs and supports both the VHDL and
Verilog hardware definition languages. ISE must be licensed from Xilinx, although the Xilinx University Program (XUP) provides free licenses for most academic
users.
The Xilinx ISE WebPACK™ is a subset of the full ISE tool that anyone can download for free from the Xilinx web site. It requires a free license that can be
obtained via registration on the Xilinx web site. WebPACK provides basic design entry, synthesis, and simulation support for the smaller devices in most chip
families. It does not provide advanced floor-planning and optimization tools.
In addition to the ISE-based logic design tool sets, Xilinx provides the Embedded Development Kit (EDK). EDK is used to develop processor-based designs using
either the MicroBlaze soft processor core, or the PowerPC hard processor cores available on some of the Virtex FPGA families. EDK must be licensed from Xilinx
and there is no free subset currently available.
There are also various third-party design entry and synthesis tools available, but Digilent is unable to provide recommendations or support for them.
In addition to design entry and synthesis tools, software is needed to download the design into the board. There are two primary options for this. Most
Digilent programmable logic boards can be programmed using the Xilinx iMPACT tool, which is part of the ISE and WebPACK software products. Some Digilent
boards, such as the Basys2, require the Digilent Adept software to download designs onto the board.
The Xilinx iMPACT tool is compatible with any Xilinx programming cables, the Xilinx USB interface, and the JTAG-3 cable. The Digilent Adept software is
compatible with the Digilent USB interface. Xilinx and Digilent both have USB interfaces, but they are incompatible. Some Digilent boards, like the Basys2 and
Nexys2, provide the Digilent USB interface. Other Digilent boards, like the XUP-V2Pro and the Spartan 3E Starter Board, provide the Xilinx USB interface
(licensed from Xilinx). The appropriate programming software to use depends on the specific USB interface on the board.
Most Digilent programmable logic boards provide a 6-pin JTAG header. Any Digilent programming cable, either parallel port or USB-based, can be used to
program the board via this header, even if the board also contains an on-board programming circuit. Using this header and a JTAG-3 cable, any board can be
programmed using the Xilinx iMPACT tool.
XUP-V2Pro & XUPV5 boards: These boards ship with the necessary power supply and programming cables, and are primarily intended for use with the Xilinx
EDK, although the ISE tools can be used to develop logic-only designs. However, the feature sets of these boards are sufficiently large and complex that
taking full advantage of their capabilities requires the use of Xilinx EDK.
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Make sure you are using the latest version of the appropriate Xilinx design software. Uninstall the old version first, then install the newest version. Also make sure that you have installed the latest service pack for the design software you are using. We are able to answer board-specific software questions, but general software support questions should be directed to Xilinx.
If you still have questions, contact us at support@digilentinc.com. Please be sure to identify the software package that you're using, the service pack, your
operating system version, as well as a thorough description of the problem and any relevant screenshots or error messages.
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