VHDL or sometimes known
HDL (High Descriptor Language) is a programming language used in describing
a hardware (i.e digital systems). It is also known as a documentation
for the construction of hardware chips, IC(s), devices. The VHDL concept
was initiated by the American Department of Defense.
Previous approach in designing electronic circuits;
If we are suppose to construct a very big electronic
system like a small microprocessor system application, we can either
try to use CAD tools to draw the schematic diagram. The schematic capture
software will then convert it into a netlist file and then use a PCB
CAD software to generate the PCB layout. Looks simple at that point
of view.
The problem with that approach is that the engineer
must make sure that all his connections are correct, block to block
inter-connectivity, and the most tedious of them all pin to pin connections.
One small mistake can damage the whole design proccess. If the system
is really big, it would take a very big amount of time to develop and
an exhausted engineer. Try to imagine how to construct a 32 bit microprocessor
with millions of connections involved.
The HDL Concept;
In HDL, we do not talk about any physical parts like
electronic chips. In HDL, every digital electronic device can be represented
by lines of program. Pin to pin connections are not that important here
in this level. Since digital electronic devices are represented by programs,
interconnectivity of the different electronic devices is done by programs
also, making the whole process flexible. At this level, construction
of electronic devices can be acheived through programming.
The HDL programming can do simulations to verify functionality
of the electronic design. If the testing and simulations are complete,
the HDL programming software will produce the Synthesizable File which
is actually the blueprint or layout of the whole electronic system being
designed.
The synthesizable file can be dumped to an FPGA (Field
Programmable Gate Array) chip which will do the routing inside the chip
or can be given to a foundry to manufacture an ASIC (Application Specific
Integrated Circuit).
RPB
