XP2 Board: JTAG scan with ispVM

Back in business, and ain’t it grand! So I decided to go with option number two and bring my old PC back to life. I could not stand the though of having to reboot between Mac OS X and Windows.  With the old PC I have not tried to build any designs or run any simulations yet, but the machine should be able to handle it, perhaps quite slowly though.

To continue with my exploration of the XP2 board, I thought it best to make sure that I could see the FPGA in the JTAG programming chain.  JTAG is an simple interface used for testing silicon devices on a circuit board, and it is also a common interface for programming FPGAs during the design and testing phase in the development cycle.  Every FPGA vendor has its own tool for programming devices, and for Lattice FPGAs the tool is ispVM.

Lets get started.  First the XP2 board must be connected to a JTAG programming cable using the J3 connector labeled “JTAG” on the circuit board.  For the parallel port programming cable supplied with the XP2 Brevia Kit, just follow the directions in the QuickStart guide.  For the USB programming cable, note the the names of the different wires, and then use the QuickStart guide to match the wire name to the right pin.

Once the cable is connected correctly, supply power to the XP2 board and launch ispVM.  After it opens, I like to close all of the open windows in the GUI and start fresh, as shown below.

To perform a simple JTAG chain scan, press F2 or select from the menu bar ispTools->Scan Chain.  ispVM reports all of the devices in the JTAG chain connected to connector J1 on the board. For this XP2 Brevia board, the only device is the XP2 FPGA itself.  In more complex designs, it is not uncommon to have several devices in the chain, such as a flash memory for device configuration, FPGAs, CPLDs, and even embedded processors like PowerPC or DSPs.  When the scan is complete, the XP2 FPGA should be visible and the only device:


XP2 FPGA found from the JTAG chain scan

As expected, the device is visible and we have also gained some basic familiarity with the ispVM tool.  With both the serial port verified with the demo program and the JTAG scan completed, the basic connections to the outside world are verified.  Before creating a simple design and programming it to the device, there is one more critical step that requires attention: power and clock systems on the circuit board.  And that shall be the topic of the next post!


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