UPC EETAC Bachelor's Degree in Telecommunications Systems and in Network Engineering EEL

Chapter 2 problems

      - A2.6 -

-- Analysis of an asynchronous circuit




1. Specifications

Fig. 1 represents the internal circuit of chip 74LS290 containing several chained flip-flops and logic gates from its datasheet. Let us adapt it as usual to our naming style and conventions.

We can use our set of tools to analyse Circuit_B represented in Fig. 2 built using this chip resources and external logic gates.

Circuit 74LS290

Fig. 1. 74LS290 chip equivalent internal circuit.

Read its datasheet to determine how does it work (what is the funcion of each pin). Some J and K inputs are not driven, we will assume that they are connected to '1'.

Analyse Circuit_B in Fig. 2 using method 2: Proteus capture and simulation, or method 3: VHDL synthesis and test. Determine how does the circuit work, meaning finding the vector output P(4..1) in a clocked (CLK) timing diagram. 

What is the maximum CLK frequency when picking the PLD target chip indicated below?

 - Cyclone IV


Test your solutions using method 1: handwritten analysis.


Fig. 2. Circuit_B to be analysed using our three methods.