ISP Cable Overview

There are two cables available for use with Xilinx Alliance and Foundation software. The XChecker Cable (model DLC4) is an RS232 serial cable. The Parallel Cable III (model DLC5) supports the JTAG standard.

Selecting A Cable

Determine the most suitable cable to use, depending on the tasks you wish to perform.

• The Parallel Cable III has significantly faster run times than the XChecker cable. This cable can be used to download and readback configuration data. The Parallel Cable III connects to the parallel printer port of a PC.
  
  
• The XChecker Cable connects to the serial port of both workstations and PCs. This cable can be used for design verification and debugging in addition to data download and readback.
  
  

NOTE

Always set the configuration mode of the device being configured to slave serial, no matter which cable you use.

Supported Devices

Since both cables can be used to configure FPGAs and CPLDs, the following Xilinx families are supported.

• XC3000, XC3100, XC3000A, XC3000L
  
  
• XC3100A
  
  
• XC4000, XC4000E
  
  
• Spartan Families
  
  
• XC9500
  
  

  ---

  NOTE

  The two Spartan families are named XCSnn and XCSnnXL, where "n" represents the device number.

  ---

Software Support

Make sure that you use the appropriate configuration software for your device type.

• JTAG Programmer Software is used to configure FPGAs and CPLDs, and supports both the XChecker and the Parallel Cable III.
  
  
• Hardware Debugger Software supports both download cables and is used for FPGA configuration. This is a GUI-based program with a waveform-viewer.
  
  
• XChecker Software is used for FPGA configuration. XChecker is a command-line text only software package, and it only supports the XChecker Cable.
  
  

NOTE

For specific information on using the download cables with the Hardware Debugger Software, see the Hardware Debugger Reference/User Guide. Consult the JTAG Programmer Guide for more information about using this software.

Previous Cable Versions

This section details considerations for using previous download cables with the Hardware Debugger Software.

You can use Hardware Debugger software with all previous parallel and serial download cables. However, these previous cables can only be used to download a configuration bitstream, they cannot be used for readback.

You are also encouraged to use the XChecker cable with the Hardware Debugger software to replace previous download cables and download programs.

If you do use Hardware Debugger with a previous download cable, keep the following points in mind.

• Previous versions of the download cable were made to download XC3000 and XC2000 designs, not XC4000 designs. The basic limitation of the previous cables is that they do not have a PROG pin to initiate a re-program in XC4000 devices. They also do not have an INIT pin to check for Cyclical Redundancy Check (CRC) errors during configuration.
  
  

  ---

  NOTE

  To use a parallel download cable to download designs to the XC4000 family devices, you must manually toggle the PROG pin to low. PROG is active when it is low. (The Parallel Cable III has a wire for the PROG pin.)

  ---

• Previous download cables do not support readback or verification.
  
  
• For the PC, the download cable is a parallel cable, requiring connection to the parallel port. (The XChecker cable is serial.)
  
  

There are only two situations when you might prefer using previous download cables instead of the XChecker cable.

• You have circuit boards with header connectors keyed to match the previous cable headers. However, you could use the XChecker cable with its flying lead connectors. Simply match the labeled flying leads to the equivalent signals on your system.
  
  
• You have circuit boards where power consumption is a critical factor. (The XChecker cable requires about 100 mA; the parallel cable used with PCs draws less power from the target LCA board.) In such cases, you may use the Hardware Debugger software to download the bitstream.