Counters Challenge1. Set up a Divide-by-2 counter using one D-flop from a 74HCT74N chip. Drive the counter with a square wave from a 555 Timer that you've set up to have a period of about half a second. Drive a red LED with the 555 Timer's square wave, and a green LED with the Q output from the D-flop. At what rate should the green LED blink? How can we interpret the green and red LED's as numbers? 2. Add two more stages to the Divide-by-2 counter from above, making a 3-bit ripple counter. Drive an output LED with each Q outout, and watch it count happily. Now, use a scope to watch two of the Q outputs. Expand the time axis to see the propagation delay. How much delay is there per stage? 3. Set up a synchronous counter using an SN74HC193N chip, or similar. Drive the UP and DOWN counters with straight (not-debounced) logic-level pushbutton inputs. Drive LED's from the Q-outputs. Click along with your pushbutton UP. What problems do you find using a not-debounced switch to clock the counter? 4.Add a debouncer to the UP clock. Design and build a Divide-by-5 counter, using only the SN74HC193N, and the debounced UP input. The Divide-by-5 counter should light an LED every 5th time the user has pressed the UP pushbutton. Hint: you'll need to use the LOAD' function of the chip, in conjunction with CO'. |
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