Two Semester Course Syllabus – Digital Term
Physics 123b/223b: Introduction, Spring 2023 |
| Feb 22, 2023
What’s in This Handout
Contents
1 Course Format and Goals1.1 Course coverage The spring 2023 version of 123b/223b will not teach the full course material of Learning the Art of Electronics. It will cover the digital half including programmable logic, the revamped microcontroller material, and [mixed signal] data conversion. We will not cover the analog portion of the material so if you you need to learn about bipolar transistors, JFETs, RC/RLC circuits in the frequency domain, filters, operational amplifiers, voltage regulators, instrumentation amplifiers, lock-in amplifiers and PID controllers, you should wait until the analog part of course is offered. The two parts of the course are designed to be self-contained, you can take, one, the other or both depending on your interests and needs. 1.2 About the course in general This course tries to teach you enough digital electronics so that you can do useful design work in a laboratory. The course achieves this very broad coverage at the expense of depth. But that does not mean that your designs will be second-rate: the premise of Horowitz & Hill’s text is that a person need not go through the rigors of three or four terms at engineering school before designing useful circuits. At term’s end you will have seen a lot of standard digital circuits, constructed circuits inside programmable logic and will have programmed a tiny computer to control a variety of peripherals. You will be a novice, but a novice well-equipped to continue learning. Datasheets that now are opaque to you should, by term’s end, be intelligible. Lots of scary schematics will have ceased to scare you. We will meet twice each week. Some lectures may be prerecorded and available prior to the class meeting so that we can begin building in lab after a short review (a “reverse classroom”). We will devote the first part of the afternoon to a discussion of the current topics, which are defined in part by the lab exercises and in part by the reading and, when available, the prerecorded video. The small class size permits us to work in an informal seminar-like atmosphere. After the discussion, you will spend the remainder of the afternoon building circuits on our breadboards with the course staff available to help get things working (you can’t learn electronics without actually doing it). The course covers a lot of material and does take a lot of time. It has the reputation of being equivalent to 1.5 to 2 full courses. The work is so different from what you are asked to do in an ordinary Physics course, however, that you may find it restful: an afternoon of occupational therapy, spent pushing little wires into holes: building things–then finding out why they don’t work. (Ok, that last part may not be so restful.) Because we are only covering the digital half of the course the pace should be somewhat slower than when we tried to cover the entire book in one semester. This course resembles (the late lamented) Engineering Sciences 54 in its hands-on quality, and in its emphasis on practical design rather than theory. It differs from ES54 in covering a broader set of digital topics in somewhat more depth, but we do not provide the final project-building experience of ES54. Until late in the course, each circuit that you build will require no more than perhaps 20 to 40 minutes to build and try. A few labs ask you to do more: Lab 18a, in which you build a digital circuit that you designed earlier and the final microcontroller lab, in which you implement a design of your own. In many cases we will ask you to design a circuit as part of the homework, then implement it in lab. Compared to a course like Engineering Sciences 154 (electronic devices and circuits) Physics 123b/223b is both broader and shallower. We will not cover the theory in depth, but we will build many more circuits. At the start, we remind you of Ohm’s Law; by the end you are programming a microcontroller. Note that because we are only covering the digital portion of the course, the content this term will be quite similar to CS141. This is a graded course. We don’t allow students to take it Pass/Fail and we don’t accept auditors. There are normally no additional requirements for students taking the course for Graduate credit; however, graduate students needing to show additional work for Graduate credit should contact the Instructor to discuss an additional design project. 2 A Rough Map of the Course Schedule2.1 A sketch of the course topics
Passive Circuits: DC, RC Time Domain Circuits, MOSFETs as switches (a review of the analog term if you took it already)
Logic: Gates, Flip-flops, Counters & FPGA’s (programmable logic devices), Memory, Project lab Conversion: Analog⇔Digital Microcontroller: C code, Assembly language, Programming Environments, Debugging, Peripheral devices, I/O interfacing, Parallel buses, Serial buses, RTOS 2.2 Relation to the analog portion of the full Physics 123/223 course The analog course is not a prerequisite for this course. Only occasionally will we speak in terms that require an understanding of analog electronics, and when we do, we’ll also pause to translate what we’re saying! The first two sessions will cover the basics of current voltage, resistance and capacitance. We will build logic gates from transistors in the first digital lab–but not before discussing the basis of all modern digital devices, the MOSFET switch. After that we’ll do what everyone else does: treat the digital devices as black boxes that work. We’ll return to consider the input and output characteristics of gates when we treat interfacing among logic families–but we will never ask you to understand a transistor as anything more complex than a switch: ON or OFF. 3 Staff3.1 LecturerDavid AbramsEmail dabrams@fas.harvard.eduTelephone:Office:Office Hours: Monday 10am to 11am or via Zoom by appointmentI encourage you to take advantage of my office hours. It is included in the price of tuition. I expect everyone to set up at least one initial meeting with me during the first two weeks of the course to get acquainted. 3.2 Teaching Assistant(s):TBD TF Office Hours TBD (but last term Sunday 2pm to 5pm in SC206) Extra Lab Time Same as TF office hours 3.3 Inclusion and BelongingWe strive to create a learning environment where every student belongs and feels welcome and valued. We need your help to accomplish this goal. If something is said by anyone in class or in a meeting that makes you uncomfortable, or if there is course material that feels insensitive, please talk to the instructor or TFs about it. If you prefer, piazza allows you to communicate with us anonymously. 4 Labs, Problem Sets, Quizzes & Exams4.1 ExamsA 90 minute midterm exam will cover the material in the first half of the course. The Mid-Term will be held on April 4, 2023, during the normal class session time. A final exam will cover all course material. The final exam is scheduled by the Harvard registrar for May 8 at 2pm. 4.2 Ungraded Quizzes (i.e., Warm Up Exercises)None that are graded—but often you can expect to be asked to try a task that does not count at all for a grade while watching the lecture/demonstration videos. The purpose of these short exercises is to give both you and the course staff an idea of what you understand and what you are confused about. 4.3 Reading AssignmentsThe Laboratory Manual for the course is almost 1200 pages (not including the online chapters) but we don’t expect you to read it all. We do expect you to read the day’s assigned classnotes and lab (the “N” and “L” portions of the chapter) before you come to class. You can read or ignore the other sections (explanations of particular topics and worked examples) unless specifically assigned, but you may find them helpful in preparing for the mid-term and final or understanding a confusing point or concept. We will list the notes and labs you have to read on the Daily Class/Lab Assignments page. Some parts of the notes will be skipped by design. For example, the second class only covers RC circuits in the time domain so you do not have you read the note covering frequency. 4.4 HomeworkWe will give out homework assignments, approximately one per week on Monday (on Canvas) and in hard copy in class in Tuesday. Homework is due a week later on Tuesday unless otherwise noted. Homework is due before class Tuesday in the Homework drop box as you come into class. If you are not attending class on a given Tuesday, there is a Physics 123 mail box on the first floor past the water fountain. (But if you use the drop box lets us know — we do not ordinarily check it.) Optionally, we will accept an electronic submission with advance permission. Extensions: We are generous with extensions, if you ask David for permission before the assignment is due. We are much grumpier when you offer an excuse after you’re late. Homework Late Without an Extension: We’ll keep some discretion, here. But our usual policy is to give a maximum of 50% of the points you would otherwise have earned, so long as we have not handed out the solutions. 5 Academic Integrity PolicyWe take the following policies very seriously. We will perform thorough investigation of any breaches and report them to the Honor Council. If you feel overwhelmed/concerned about your status in the class, please talk to us! Please do not jeopardize your academic career over this class – we will work with you to get you any help that you might need. 5.1 Collaboration on Homework AssignmentsWe hope that you will discuss homework questions with your peers (i.e., students currently enrolled in the course). For many students, such discussions are the principal activity at our review sessions. Since we assume such collaboration, you need not announce it on the work that you submit—but… because homework scores get considerable weight in the course grade, and because we don’t believe you can learn the material without practicing on problems, we do not allow one person simply to copy the work done by another. If someone explains to you how to approach a problem, fine. But write out your own answer—and often a good answer will include some explanation of your method. We will look with disfavor on multiple submissions that match, word-for-word. In some rare cases it may be appropriate to acknowledge that a problem stumped you, so that you must give credit to someone who told you how to solve it. Note, however, you may not use solutions to prior term’s homework in completing the assignments. We recognize that these judgments are subtle, and matters of degree. We don’t want to distract you with writing lawyer-like acknowledgments. We do want you to worry a bit about the issue. Here is a relevant excerpt from the FAS “Student Handbook: “Students must acknowledge any collaboration and its extent in all submitted work; however, students need not acknowledge discussion with others of general approaches to the assignment….” To the extent that our discussion of collaboration seems to modify this policy, our discussion controls. (Even though we allow you to collaborate on homework assignments there are good reasons not to. It is far too easy to believe you know how to attack the material after working with others only to be rudely surprised on the exams where you have to solve the problems by yourself.) 5.2 Midterm and Final ExamAll work on the midterm and final exam will be entirely individual. Collaboration or use of non-approved external resources is not allowed. In general, we do not have makeup examinations available. If you miss an exam for any reason, you must notify David Abrams by email as soon as possible with the reason for your absence, and you must provide us with documentation that justifies your absence. If you do not notify us by email before the missed exam or, in the case of an emergency, as soon after the missed exam as is possible, we will count the absence as an unexcused absence, and the missed exam will count as a score of zero. The midterm exam is scheduled for Tuesday, April 4, 2023, in class. Harvard has scheduled the course final exam for Monday, May 8th at 2pm. Note that Harvard may mandate stricter rules for the final exam. 6 Grading6.1 Grading Rubric The course grade rests on roughly the following basis:
If we had a good way to measure lab performance we would count labs more heavily than this. Lab work is the core of this course. On the other hand, we’re attached to the notion that the labs should be 1) fun and 2) serve your interest in learning, not our interest in evaluating. So we think it’s probably all right that labs don’t get much grade weight, despite their importance. Please note, again, that you are expected to do the labs. We don’t require that you do them brilliantly, or that you finish each long lab, but that you stay for the lab session and make a reasonable effort to do the labs. If you don’t want to do labs, don’t take this course. If you don’t do nearly all the labs, you will not pass the course. (Probably this remark strikes you as strange, but it reflects occasional misunderstandings in past years.) Part of this evaluation is class participation. The course is more enjoyable for me with your active participation (and it gives me feedback on what you are having trouble with) so we include it in this section of your grade. Note, we are not grading you on providing the correct answer in class, only your willingness to participate in the class discussion. 6.2 Grading PolicyI have a reputation as a harsh grader. This reputation is not wholly undeserved. I don’t see how you can learn if I don’t point out what is wrong with your work. I hope you will use my notes and comments on homework and exams (in ugly red ink) to figure out what you don’t understand and what you need to study so you will do better the next time. To make up for the scary grades on homework and exams, I curve the final grades based on a number of factors. Usually, students receive a final grade one to two grades higher than their numeric scores would suggest (unless your numeric score is 93 or higher in which case you are out of luck for a curve upwards). This is not a guarantee but I do try to make the grading fair considering the amount of time and work the course takes and my grading philosophy that telling you something is correct when it is not is not conducive to learning the material. 6.3 Lab reports? No!We do not expect lab reports, and we barely grade lab performance (see just above). But we do expect you to do all the labs. If you don’t do the labs, you can’t pass the course. As we have said elsewhere, people often fail to finish the labs, and we don’t want you to worry if that happens to you. You should worry if you fall far short of finishing, and do this repeatedly. If that is happening, you should try to push yourself to move faster on the early sections, so as to distribute your precious time more evenly over the lab work. Don’t stay stuck for long: ask for help, when something in lab refuses to work, or makes no sense. We understand that much of our job is to get you unstuck. 7 Texts7.1 The Main TextThis is a book that embodies the course, in day-by-day doses: Learning the Art of Electronics, 2nd Edition by Tom Hayes and David Abrams with Paul Horowitz (2016, 2024). We’ll refer to this book as “LAoE.” It is available in hard copy and Adobe eBook Reader format. You will need to buy or rent this book for the course. (However, the material for the first two classes is posted on Canvas so you can hold off if you are still deciding if you want to take the course.) Warning – the second half of new edition (2nd ed. 2024) is entirely different from the first edition. You should not try to economize by buying a used copy of the old edition (which we will refer to as “LAoE_1”). We will cover a half or full chapter from the book in each class period. Each daily dose includes. . . Class Notes (“N”) These present the day’s topics much as the live or recorded talk does—but the typed class notes are much tidier and more complete. These you should read before coming to class. Lab (“L”) There is one for each of our meetings. You should flip through this so that you know what you’ll be doing in lab. The building of circuits goes much more smoothly when you can anticipate what you’ll be building. And knowing what’s in the lab will let you make choices about what parts of a lab to hurry through—or even to skip— in the event (not rare) that you find yourself strapped for time. We will be adding some additional lab material to take advantage of the FPGA and trimming some of the labs or splitting them over two sessions. Supplementary Notes (“S”) These you can read or ignore (unless specifically assigned). They treat a topic, offering an explanation that you may or may not find necessary. For example, on the first day, you’ll find a handout on reading resistors. If you’re familiar with this process, skip this handout entirely. Worked Examples (“W”) These are design problems, and may not interest you much as you prepare for class. But these can become keenly interesting when you’re working on a design for homework. Online Content (“O”) To avoid giving you a hernia (and to make the book publishable in one volume), we have moved some material online. These chapters are usually something you never need or only need once, or something that could change often and does not belong in hard copy. We will occasionally assign some material from an online chapter to read before class. 7.2 Posted ReadingsWe will also post modifications to the readings in LAoE on the Daily Class/Lab Assignments page so always check there before doing each assignment’s reading. 7.3 An Excellent Reference Book (not required)Horowitz & Hill, The Art of Electronics, (Third Edition, 2015). This is a great reference book— almost surely the best general trove of circuit-design wisdom that you will find. But you don’t need it to get through this course happily. After the course, you will appreciate its depth and comprehensiveness. During the course, you’ll probably feel busy enough just reading the main text. We’ll refer to this book as “AoE.” LAoE is full of cross-references to AoE—but don’t let those worry you. Those cross references are for perhaps a second pass through LAoE, when you’re digging deeper into some topic. My suggestion is that you not buy this until you finish the course. 7.4 Other Resources You Might Find Helpful7.4.1 BooksWe don’t recommend paralleling your reading in LAoE or AoE with reading another, more conventional electronics textbook. You’d end up spending a good deal of energy translating from the terms of one into the terms of the other. The engineers’ treatment would be much more mathematical than ours (and, we think, less helpful for development of intuition). But if you’d like a second source. . . . . . this is the text that was used in the SEAS’ introductory electronics course, Eng Sci 54: Scherz & Monk, Practical Electronics for Inventors, (Fourth Edition, 2016) ISBN-13: 978-1259587542 ISBN-10: 1259587541 This book is available in the Science Library, at the Coop and for online order at Amazon, Barnes & Noble, Walmart, Alibris, AbeBooks, and other vendors. The list price for the book is $40. It (or an earlier version) may also be available online in the Harvard Library system. Some books for hobbyists and tinkerers can help to fill in background that we forget to explain (how instruments work, for example). Here are a few that looked good, to our hasty appraisal, plus one conventional treatment of electronics, in the style of an ordinary engineering course:
These may be less useful this semester since we are not covering the analog material. The “Additional Resources and Interesting Stuff” Canvas page has links to some sites that may be helpful if you need some additional review of course topics. Additional books, as well as several of the resources listed above, are available on the Library Reserves Canvas page. 7.4.2 SimulatorsAnalog: This analog simulator shows currents flowing–kind of like what a science museum’s interactive demo might show: http://www.falstad.com/circuit/e-index.html Digital: This digital simulator is pretty good, too (30 day free trial; $29 to purchase): There is also a very nice, free digital timing diagram editor available at: Mixed Signal: We may try an online circuit simulator in the first few classes if there is interest. It is free but you need to register for access. Programmable Logic: We will be using EDAPlayground to check our FPGA designs. I also strongly recommend the hdlbits web site problem sets as a way to learn Verilog HDL programming. See the FPGA page in Canvas for more information. https://www.edaplayground.com/ https://hdlbits.01xz.net/wiki/Problem_sets 8 A Few Innovations, in recent years:8.1 We post just about everything on the web, including our daily handwritten notesWe’ll use the Canvas page: Lecture Slides, Notes, and Handouts 8.2 Frequent “anonymous quizzes” (warm up exercises)On many class days you will be asked to try a short quiz—without putting your name to the paper. We’ll talk about one or two of your responses in class. These quizzes are meant to let you—and your teachers—test whether ideas and skills are getting through to you. Since these quizzes are anonymous, they really test the teachers rather than you. When the material is prerecorded, the anonymous quizzes will be embedded in the lectures. While it is theoretically possible to match online material to individual students, we do not plan to nor is that our goal. We are much more interested in seeing what gives the group trouble and what seems clear. The exercise will sometimes ask about the material that is new on the day it is given. We do that in order to encourage you to read before coming to class. Sometimes the exercise will look back a day, on the theory that you are likely to understand better what you had a chance to try out in lab. The solutions will be posted on the Lecture Notes tab of the course Canvas site. 8.3 Problem solutions and practice examsWe hand out problem set and exam solutions in hard copy, usually on Thursday. Please do not share them or post them to the web. They are for your own use only. We normally post a practice exam followed by the solutions a few weeks before the exam date. 8.4 A New Microcontroller
The first edition of teh text offers a choice of building up a computer from parts or an alternative scheme using a single-chip microcontroller. Both employ a relatively old 8051 micrcontroller. We will do neither. Rather, the second edition uses a modern ARM M0+ microcontroller with code written in the C language. However, we will learn enough ARM assembly language to understand the debugger dissassembly and see how the compiler translates your C code to something the uController can understand. Our emphasis will be less on programming and more on interfacing the processor to external devices. We will also use a Real Time Operating System [RTOS] to control multiple processes simultaneously. 8.5 Programmable Logic Devices (PLDs)PLD’s are Programmable Logic Devices (PALs, GALs and FPGAs). PLDs provide an efficient way to make complex logic circuits with very little strain on either your brain or fingers (nothing to wire except inputs and outputs!). We’ve been including them in this course for several years, although you will not find them in the Student Manual. We will devote class, homework and significant lab time, to these devices. You will use a 5,000 Look Up Table (LUT) FPGA device to program and test multiple digital devices and systems.
9 Class Size/ConstraintsWe will have supplies and equipment to support up to 20 students (or possibly a few more) this term. We plan to have students work in pairs during lab. If the course is oversubscribed, we normally admit by enrollment date. The class requires “permission of instructor” only to avoid being oversubscribed. We grant permission in the order it is requested until the class is full then admit on a provisional basis. 10 ScheduleSee the Canvas Calendar and the Class/Lab Assignments page. |