Connecting to the XP2 Brevia Board

Much to my surprise, my Lattice XP2 Brevia board arrived in the post today.  I printed out the User’s Guide with the schematic because I know I’ll be pouring over the schematics during my lunch break at work and when I get home in the evenings.  The kit contains a null-modem (serial port) cable, the 3 inch x 2 inch board, a parallel-port programming cable, and a power adapter with exchange sockets depending on the electrical standard in your region.  This is truly a versatile development kit for experimenting with FPGAs.

Because I don’t have a PC with a built in parallel port, I have to use a USB programmer, and I’m still waiting on my Lattice USB programming cable to arrive in the post.  Note: Lattice says that USB-to-parallel converters will not work with their parallel port programming cable.

It is often helpful to evaluate the status of the board before beginning with prototyping and development.  If I had designed the board myself, I would be checking the voltage levels at critical parts in the circuit and making sure they match they intended levels.  I’d also be checking the power-up sequence and reset circuits to make sure that these basic functions behave as expected.  I trust, however, that Lattice has taken care of this.

My test plan is:

  1. Connect to the board’s serial interface via a terminal and verify that the factory-installed demo application runs as expected
  2. Connect to the board’s serial interface with my own software and make sure I can interact with the factory-installed demo application

Connecting to the board with a terminal

If you have a Microsoft Windows workstation, you can follow the Lattice QuickState guide and use HyperTerminal to connect to the board.  Though I have Windows installed through a Virtual Machine, I only use it for the Lattice FPGA design software and device programmer.  I would like to use my preferred OS, Mac OS X, for interacting with the XP2 board.  While Mac OS X does not have a graphical application like Microsoft’s HyperTerminal pre-installed, we can use a terminal tool called screen.

Screen comes installed on Mac OS X and it is accessible via the terminal (of course).  The Lattice QuickStart guide says that the serial connection parameters are 8 data bits, no parity, 1 stop bit, no flow control and a baud rate (bits per second) or 115,200.  Most of the parameters, except for the baud rate, are rather standard, so I just have to specify the baud rate when I start a new screen session.

screen /dev/tty.usbserial-A600cGQW 115200

Now I just have to press the reset button on the XP2 board:

Voila!  I am now hooked up to the factory-installed demo application.  Next I will use some custom C software and make sure I can interact with the demo application.


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