![]() ![]() In the figure, the mechanical switch is connected to a latch. The figure shows that many bounces from "0" to "1" happen when a switch is pressed. What makes this a problem is the speed of the electronic circuits, since contact's vibrations can be confused with (fast) switching. When a switch is pressed, it briefly vibrates at the contact area, which causes the circuit to be closed and opened many times before the vibration ceased. Read below about contact bounces and how to avoid them by using a latch.Īll mechanical switches exhibit a phenomenon called "contact bounce".Preparation task 2 (done before the lab).Is it possible to say that P and Q are always inverses of each other? Do you have to prohibit some input combination to make the SR-latch valid?.Now identify a, b, P and Q with the variables used in a SR-latch.You should just remove the connections you have made yourself. A weak battery can make your measurements uncertain even if you wired everything right! - Attention! You should never "tear down" the basic connections we made in advance on the breadboard. Please note! Do not have the battery plugged in unnecessarily. Operate DIL switches with a screwdriver tip to change the order of their variables to the one indicated in the table and fill in the output values. Its output value depends not only on the input values, but also on the order in which they change. The latch is not a combinational circuit but a sequential circuit. You can also simulate the circuit with LTSpice on your own computer at home in advance.Ĭonnect the latch on the board using the provided soft cables.(Do not analyze the input combination a= b=0, this you will do at the lab with a real circuit). Try to reason your way to a truth table for the circuit. NOR-gates are in the chip 7402, choose two gates from the chip and enter their pin-numbers in the figures - it will facilitate the connection work at the lab. Preparation task 1 (done before the lab).In this case you have to read the course material yourself in advance - there are links to all slides off the lectures and exercises.Ī picture of the lab equipment. To the right there is a buffer circuit, this portion of the lab equipment is not normally used. Practicing measurement techniques, examining a sequential circuit by "forcing" it to run through different cycles.Īttention! Your lab time may be prior all lectures and exercises that may be needed for the lab have been given.Practicing the construction of a state machine using a systematic method.Showing how the high speed of electronics cause problems, and giving a practical example of a solution.Orienting yourself on programs for electronic simulations.Orienting yourself on latches and clocked flip-flops.The task will be to "control" such a sequential circuit to run through various cycles. Other sequential circuits with simple structure, such as feedback shift registers, can often be examined directly. With a systematic method you will construct a state machine, a controlled counter, which you then test in the laboratory. On the breadboard you will connect and measure some basic sequential circuits like latches and clocked D flip-flops. ![]() CMOS gates only consume power at the clock pulse edges! (In the lab equipment it is the LEDs that are the big "power consumers"). It's the CMOS technology that has enabled extremely low-power battery-operated portable devices. We continue to use standard CMOS circuits. ![]() This lab is about designing synchronously clocked sequential circuits. Save the receipt until you have received the full course registered in the database (Ladok). Your booklet's front page is used as a receipt that the lab is completed. Both students should bring their lab booklets. If a preparation task has this "label", you must also be prepared to present an oral solution for your peers at the lab.ĭuring the lab you work in groups of two, but both students are responsible individually for their preparation and implementation. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |