ECPE174
ADVANCED DIGITAL DESIGN
LECTURE NOTES
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USING DEVELOPMENT SYSTEMS TO CREATE COMBINATIONAL CIRCUITS
- Circuits can be designed much the same as when using discrete logic ...
1. DESIGN
- all you need is Schematic Capture software
- or use PALASM or VHDL or Verilog
- just make sure the logic blocks you use are available in the software's library
- you can create your own hardware macros to create your own ALUs, for example.
2. FUNCTIONAL SIMULATION
- checks for proper function, but does not account for circuit delays (not known yet - not
until actually in PLD)
3. ROUTING
- a router determines how to configure & interconnect FPGA modules to produce your
circuit. It may require some help from you. It may request circuit simplification. It may not be
able to get your whole design on 1 FPGA, requiring you to split the designbetween two or more
FPGAs.
4. BACK ANNOTATION
- the development system determines the circuit delays and back annotates those delays
into the simulation.
5. SIMULATION - The normal steps of logic design should be:
a. block diagram
b. schematic capture, HDL
c. computer simulation
d. redesign/re simulation until it works
e. prototype and testing
5. PROGRAMMING
- some PLDs can be programmed only once. XILINX uses RAM, however. ALTERA
uses true EPLDs; however, its largest PLDs also use RAM to store program data.
6. TESTING - if it doesn't work, start over.
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