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Unit 3: Simulation of Continuous System (II)
Digital Simulation Notes
You will simulate a 4 bit Successive Approximation ADC prepared up of a DAC, comparator, D
flip flops, J-K flip flops, and NAND gates. You will enter a DC input voltage, run the simulation,
and read out the digital state of the circuit under the control of CLK pulses. The circuit also
involves START and CLEAR lines.
1. Enter the circuit via schematic capture.
2. The initial conditions for the various lines are entered using the Word Generator tool,
which permits you to enter the CLK, START and CLEAR pulses and execute them as a
sequence either step by step or as an automatic series at a specified frequency.
3. Use the Logic Analyzer tool to exhibit the circuit output. This permits you to display the
waveform on up to 16 channels concurrently. The analog output can be viewed on the
Oscilloscope instrument. The DAC ouput is Vout = Vref × D/256 where Vref = 5 V. The
binary outputs can also be viewed with LEDs which light up on a logical “1”.
4. Make a plot of the DAC output as a function of consecutive clock pulses. You should observe
the DAC output congregate to the analog input voltage with an accuracy reliable with the
4bits of the circuit, i.e. one part in fifteen. The digital result exists in the four D flip flops.
Try numerous different DC input voltages.
Case Study Indiasoft Tech to Market Simulation Tool
he Pune-based Indiasoft Technologies and the UK-based software developer Lanner
launched Witness 2006, a modelling-cum-simulation software targeted mainly at
Tmanufacturing companies in Chennai.
The product has been developed by Lanner and Indiasoft Technologies will distribute and
maintain the product in India.
The software will focus on optimising workflow in a manufacturing organisation. Using
simulation tools, the software will arrive at the most efficient workflow or process for the
company, said Mr R.K. Irani, Director- Operations, Indiasoft Technologies. The company
is aiming to address supply chain logistics process that is inefficient in most organisations,
he said.
Six modules of the software are available. The basic one “Witness 2006”, is a modelling
and simulation tool, the next one Optimiser helps optimise results derived from Witness
2006. “We expect to see maximum demand for these two modules,” said Mr Irani.
The other modules are Virtual Reality (VR) that helps create a 3D virtual plant complete
from inventory to finished product, Documentor (that stores the logic of processes and
other results), Witness Miner (for data mining) and Witness SDX (a communicative tool
that links Witness with Factory CAD).
Witness 2006 has a standalone and a Network (Enterprise) edition and is priced between
13 lakh and 23 lakh, depending on the modules incorporated.
The company is looking at discrete component manufacturers, specifically in the
automotive, mechanical and aerospace division.
Indiasoft’s clients include Bajaj Auto, Varroc Group and SKF. The company recently
distributed Witness-2006 to eight educational institutes.
Source: http://www.thehindubusinessline.in/2006/07/07/stories/2006070703320400.htm
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