Changes

== Design example ==

== Design example ==

To illustrate the discussions in this tutorial, a design example is discussed along the way.  The design example is the [[http://zeus.phys.uconn.edu/wiki/index.php?title=Programming_the_FPGA#Emulator_.28D.29|emulator for the AD5535 DAC]].  As each step of the design process is discussed, the DAC emulator will be used for illustration.

To illustrate the discussions in this tutorial, a design example is discussed along the way.  The design example is the [[Programming_the_FPGA#Emulator_.28D.29|emulator for the AD5535 DAC]].  As each step of the design process is discussed, the DAC emulator will be used for illustration.

== Where to start ==

== Where to start ==

=== Example: the block box ===

=== Example: the block box ===

For the DAC emulator, the inputs are clearly defined for us.  The AD5535 data sheet discusses the [[http://zeus.phys.uconn.edu/wiki/index.php?title=Programming_the_FPGA#Interface_.28D.29|serial interface protocol]] in detail.  We need four input lines:

For the DAC emulator, the inputs are clearly defined for us.  The AD5535 data sheet discusses the [[Programming_the_FPGA#Interface_.28D.29|serial interface protocol]] in detail.  We need four input lines:

* ''/Reset'': an asynchronous, active-low reset line

* ''/Reset'': an asynchronous, active-low reset line

* ''D_in'': serial data line

* ''D_in'': serial data line