Digital Logic Design Aaron Tan Pdf
Vannessa Rataj
A fellow student at my University asked me the other day if I could design a circuit board for a workshop teaching how to solder. I immediately accepted because I've been wanting more experience with designing boards for the CNC machine at our school. Deciding what I wanted to make was hard, because it had to meet the obvious criteria of being cheap to produce and having a low part count, but it also had to be fun. I thought about sound circuits since that was how I first learned electronics and later went on to design Analog Synthesizer boards.
In the end however, I decided I wanted to be more educational about things. So I choose to combine the basic comparative logic circuits onto one PCB so they could see how they work. The final design allows the user to use a 8 Pin DIP Switch Package as inputs to the circuits and see the result on an LED.
You can almost tell how it's layed out if you looked at the Hyper Physics page. Each row, of resistors and transistors is a gate. The 8 resistors are the inputs into the base of transistors. In the AND and OR configurations, the drop down resistor is placed at the bottom, and in the NOT configurations they are at the top. Finally, each output signal is passed through a current limiting resistor before heading into the LEDs.
If you want to build this too, I have the EAGLE schematic and board files on my Github Page. The board was designed specifically for CNC milling, but I may go ahead and make a version thats more compact and suitable for fabrication in the future.
I am officially back in the world of "I don't know what the hell I am doing or why I am doing it" ?. I think I understand the components and the math behind them, but in my experience, there's a big gap between theory and practice when it comes to electronics. I have never designed a PCB before, and have very little experience making circuits at all, but I am excited to learn more. Electronics is a big part of my field so I need to get comfortable with it. The group assignment this week is to use test equipment in the lab to observe a microcontroller circuit board during operation; and the individual project is to redraw an echo-hello-world board and to add at least a button and an LED to it.
This week, Ahmed took us step-by-step through the electronics design workflow. Using KiCad, he walked us through the process of how to create a schematic that defines the logical connections in the circuit and then to generate from that, a blueprint to define all of the physical placements and connections. He also showed us how to access the Fab libraries in KiCad so we can use the footprints for the specific components that are available in the lab. I can only imagine how much time and effort that saved us so I appreciated it. Looking forward to getting started.
We have been encouraged to try to make these weekly projects relevant for our final projects, so I sat down with Marcello and discussed my project, what I would like it to do, and what I will need to be able to accomplish it. He told me that I would basically just need an Arduino Uno, and advised me to attempt my own satshakit. Originally designed by Daniele Ingrassia, the satchkit, is an open source board that is 100% compatible with the Arduino IDE and libraries. This board is definitely more ambitious than I would have attempted this week, but I will feel great if I am able to pull it off! I was also worried that it might not count for this week's assignment, but he assured me that it would as long as I added at least an LED and a button to it. I decided to add a button and six LEDs for reasons that will become apparent in my final project soon ?. Using a very difficult to read schematic from another version of the satshakit as a reference, I set out to build my own.
I wanted to be careful to not make the schematic so busy that I couldn't read it anymore, so I also employed a lot of tags using the Add a Global Label tool. This is very convenient for keeping the number of wires down on complex boards.
In the Run Footprint Assignment tool, I chose the proper footprint for all of the components. Apparently, there is no footprint for the ATmega328P so I had to use the footprint from the Microchip library, once again, after stopping off to double check the datasheet to make sure they were the same as the ones we have in the lab.
I tried to use the Auto-Place Footprints tool from the Place menu, but it just took a long time and didn't really give me anything that made sense so I ignored it and just moved things around by hand for a while until I was satisfied that I would be able to connect the necessary traces.
Using a combination of adjusting the Constraints, Pre-Defined Sizes, and Net Classes in the Board Setup and playing around with the Edit Track and Via Properties tool in the Edit menu, I was able to change my track width from the default 0.25 mm to 0.35 mm.
So I got back in Inkscape. I had changed the color to white already so I knew I had to be missing something. Eventually, I found this handy guide that explained what I needed to do. Turns out, I had changed the color to white already, but the A-Level (A for alpha) defines the opacity of that chosen color. I set it to 100 and my problem was solved.
The image was working properly, so I was finally able to use MODS to create the gcode for cutting the PCB on the Genmitsu. I did the traces and drills first using the parameters that I discovered a few weeks ago during the Electronics Production week.
...and this line that tells the machine to pause for one second after not turning on the coolant. I have no idea why these two lines created such a problem, or why I did not encounter it the first few times I used the 3018 Pro, but the solution was easy enough once I discovered the problem.
Then, using the method Ahmed showed us a couple weeks ago, I collected all of my components. Unfortunately, we didn't have any 16 MHz crystals that were SMD, so I decided to use one that is 20 MHz. According to the datasheet for the ATmega328P, this is no problem as long as I supply 4.5 - 5.5 volts. Apparently it might cause a problem later with the bootloader, but it can always be replaced if necessary.
Soon after starting, the missing trace was FINALLY noticed and the haunting began. Thankfully I still had some material between the two pads that were meant to be connected, but unfortunately, the mill had already cut all the way around them both. The only option I could think of was to finish cutting the trace with a razor blade, and then to carefully bridge the gaps with solder.
I also managed to completely mangle the installation of the 1x2 pinheader. I bumped it with the soldering iron and pulled up the very thin copper traces on both sides. I couldn't leave it that way, so I cut the traces where they were still connected to the board, and I used small jumper wires to bridge the long gaps. This was tedious, and I wished I had more hands throughout the whole process. These two solutions are pretty janky, but they worked in the end.
I am pretty happy with my work overall! This is a challenging board for somebody who has never made a PCB from scratch before...and the SMB components tested both my skill and my patience. I really hope it works! I am confident that the connections are good, but not noticing that missing trace really shook my confidence in the design itself. Fingers crossed!
A fundamental question in Josephson junction physics is the temperature at which quantum tunneling becomes the dominant source of junction escape as opposed to thermal excitation. This quantum crossover temperature is important to the design of classical superconducting circuits, as it dictates the minimum error rate that can be achieved for a given junction size. This property has been previously described and measured for over forty years, but the measurement technique is limited to single junctions and not extensible to junctions embedded in a larger circuit. Here we demonstrate a technique for measuring the quantum crossover temperature for a superconducting digital circuit by examining the width of the transition from operation to failure in a basic Reciprocal Quantum Logic digital circuit. This transition width is extracted from the broadband noise generated from the circuit errors and further, disambiguates from spectral noise, such as line noise, that can broaden this transition and artificially increase the crossover temperature. Application of this technique to a medium sized circuit demonstrates that the quantum crossover temperature of a junction embedded in a larger circuit is indistinguishable from the crossover temperature extracted from an isolated junction.
The power consumed by digital integrated circuits has grown with increasing transistor density and system complexity. One of the particularly power-hungry design features is the generation, distribution, and utilization of one or more synchronization signals (clocks). In many state-of-the-art designs, up to 30%-50% of the total power is dissipated in the clock distribution network.
In this work, we examine the application of sequential logic synthesis techniques to reduce the dynamic power consumption of the clocks. These optimizations are sequential because they alter the structural location, functionality, and/or timing of the synchronization elements (registers) in a circuit netlist. A secondary focus is on developing algorithms that scale well to large industrial designs.
The first part of the work deals with the use of retiming to minimize the number of registers and therefore the capacitive load on the clock network. We introduce a new formulation of the problem and then show how it can be extended to include necessary constraints on the worst-case timing and initializability of the resulting netlist. It is then demonstrated how retiming can be combined with the orthogonal technique of intentional clock skewing to minimize the combined capacitive load under a timing constraint.
The second part introduces a new technique for inserting clock gating logic, whereby a clocks propagation is conditionally blocked for subsets of the registers in the design that are not actively switching logic state. The conditions under which the clock is disabled are detected through the use of random simulation and Boolean satisfiability checking. This process is quite scalable and also offers the potential for additional logic simplification.
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