Course appearing in the tracks Embedded Systems and Software and Digital Systems). Students acquire the skills to describe digital systems at various levels of abstraction with the VHDL language. The Verilog language is introduced by difference. The course completes the design methodologies acquired in previous basic digital design courses and extends them to the register-transfer level. The course uses simulation-based verification techniques to develop in a lab several RT-level designs and deals with verification techniques based on formal methods, in particular combinational and sequential equivalence check and model checking. The course introduces the basic knowledge on testing digital circuits.

• Knowledge of the syntax and semantics of VHDL • Ability to describe complex digital systems in VHDL at various levels of abstraction • Basic knowledge of the Verilog language by difference w.r.t. VHDL • Knowledge of the fundamental features of embedded systems • Knowledge of the metrics to evaluate designs • Knowledge of the design methodologies for register-transfer level systems • Ability to design complex digital systems at the register-transfer level with CAD tools • Ability to verify by simulation complex digital system designs • Knowledge of the main formal verification techniques with particular emphasis on combinational and sequential equivalence check and model checking

Knowledge of basic design techniques for combinational and synchronous sequential circuits.

• VHDL: structure of VHDL files: entity/architecture; description styles: behavioral, dataflow, structural; lexical elements; objects: signals, variables and constants; data types: scalar types, composite types; operators and attributes; concurrent statements: concurrent signal assignments, generate statements, concurrent processes, component instantiations; sequential statements: processes, conditional statements, iterative statements; partitioning techniques: blocks, packages, libraries, components, configurations. Examples of combinational, synchronous and basic register-transfer level designs in VHDL. • Register Transfer-level embedded systems design: design metrics and their optimization; key technologies for embedded systems: processor technology, IC technology, design technology; single-purpose processor design: High-Level State Machines, the FSM-D model, from the algorithm to the FSM-D, synthesis of the datapath, synthesis of the control unit, description in VHDL; optimization of single-purpose processors: algorithm, FSM-D, datapath, FSM; optimization of Finite State Machines (FSMs): state minimization (simplified and exact equivalent state detection algorithm), state encoding heuristics. • Formal verification: approaches to design verification: simulation vs. formal verification; theorem proving: propositional logic, first-order logic, higher-order logic; equivalence checking: Binary Decision Diagrams, combinational equivalence check, sequential equivalence check (symbolic reachability analysis, the product machine model); Model Checking: linear-time temporal logic, branching-time temporal logic, liveness and safety properties, model checking algorithms. • Verilog by difference w.r.t. VHDL: descriptions of combinational circuits, sequential circuits and RTL designs.

Lectures (40h) covering the syllabus + 20h lab work: students work with the Xilinx® Vivado HLS package to develop RT-level designs according to the methodologies described in the lectures. An optional short assignment is available. It is an individual project, assigned mid-December, to be handed in for evaluation before the oral exam and no later than the end of February exam session. It entails max 2/30 bonus on the final mark.

Handouts published on the course site. Additional readings: • F. Vahid, “Digital Design with RTL design, VHDL and Verilog”, 2nd edition, John Wiley, 2010 • D. Pellerin, D. Taylor “VHDL Made easy!”, Prentice Hall 1997 • F. Vahid, T. Givargis “Embedded System Design: a unified hardware/software introduction”, John Wiley, 2002 • M.Ercegovac, T. Lang, J. Moreno “Introduction to digital systems”, John Wiley, 1999 •

Modalità di esame: Prova orale obbligatoria; Prova scritta su carta con videosorveglianza dei docenti;

The online and the blended online/onsite exams are identical. They consist in a written and in an oral part. Written exam (max 150 minutes): designs on paper of combinational networks, Finite State Machines and RT-level complex systems described in VHDL. Number of exercises varies according to difficulty. No books, slides or any other material allowed, except a VHDL primer. The goal of the written part is to ascertain that the student has acquired the ability to design complex digital systems and to describe them in VHDL at various levels of abstraction. Evaluation criteria: understanding of specifications, functional completeness of solution, correctness of VHDL code. No later than 3 days after the written exam, the student has to upload a simulable VHDL file and its testbench, as well as a short report focusing on the design choices and on the differences between the version handed in at the written exam and the uploaded one. If the VHDL files are uploaded before the deadline, the written exam is corrected and ranked. If the mark is sufficient (>= 15), follows a mandatory oral exam on all the topics dealt with during the course. Questions concern knowledge (definitions, concepts, etc.) and short exercises (in particular related to formal verification and Verilog). The oral exam aims at ascertaining that the student has acquired the notions in Formal Verification and Verilog that are part of the course syllabus. The final mark takes into account the results both in the written and the oral parts as a whole and not as an average. An optional short assignment is available. It is an individual project, assigned mid-December, to be handed in for evaluation before the oral exam and no later than the end of February exam session. It entails max 2/30 bonus on the final mark. Texts of past exams and solutions are available on the website. Modes: two identical modes are foreseen: online and blended online/onsite. In the online mode, the written exam is on-paper under videosurveillance of the lecturer. The video conferencing application is Virtual Classroom, available on the course site. Requirements: personal computer with webcam or tablet, printer/scanner, browser, adequate access to the network, blank paper sheets, pen/pencil. Preliminaries • the student must show his/her identification document and this will be compared with the student’s photo available in the database of the University; • a witness (who is not a member of the Board of Examiners) will be present during the exam; • the student must declare that he/she is not using any aid or support tool and that nobody is in the room to help him/her during the exam. Written exam: • the student receives the exam text by email and prints it • the student takes the exam in front of a webcam • the student must clear the desk of all objects and the PC must be placed at a security distance • at the end of the exam, the student must show his/her paper in front of the webcam and send a scanned copy (clearly legible) together with a copy of his/her identification document. Oral exam: the student joins the Virtual Classroom when invited. In the blended online/onsite mode, some students are in a classroom, other students work in remote, the exam being identical.

Modalità di esame: Prova scritta (in aula); Prova orale obbligatoria; Prova scritta su carta con videosorveglianza dei docenti;

Basic principle: adapt the existing exam modes to the remote exam mode, changing as little as possible. Structure of the exam (unchanged): • written exam (design of one or more circuits in VHDL and Verilog). Duration depends on difficulty, max duration 2h30 o focus on design: VHDL o focus on syntax: Verilog o mandatory upload of code and report • mandatory oral exam on all the topics dealt with during the course. The date of the oral exam is agreed upon by email. Requirements: personal computer with webcam or tablet, printer/scanner, browser, adequate access to the network, blank paper sheets, pen/pencil. Preliminaries • the video conference application is Virtual Classroom, available on the course site; • the student must show his/her identification document and this will be compared with the student’s photo available in the database of the University; • a witness (who is not a member of the Board of Examiners) will be present during the exam; • the student must declare that he/she is not using any aid or support tool and that nobody is in the room to help him/her during the exam. Written exam: The online and the blended online/onsite exams are identical. They consist in a written and in an oral part. Written exam (max 150 minutes): designs on paper of combinational networks, Finite State Machines and RT-level complex systems described in VHDL. Number of exercises varies according to difficulty. No books, slides or any other material allowed, except a VHDL primer. The goal of the written part is to ascertain that the student has acquired the ability to design complex digital systems and to describe them in VHDL at various levels of abstraction. Evaluation criteria: understanding of specifications, functional completeness of solution, correctness of VHDL code. No later than 3 days after the written exam, the student has to upload a simulable VHDL file and its testbench, as well as a short report focusing on the design choices and on the differences between the version handed in at the written exam and the uploaded one. If the VHDL files are uploaded before the deadline, the written exam is corrected and ranked. If the mark is sufficient (>= 15), follows a mandatory oral exam on all the topics dealt with during the course. Questions concern knowledge (definitions, concepts, etc.) and short exercises (in particular related to formal verification and Verilog). The oral exam aims at ascertaining that the student has acquired the notions in Formal Verification and Verilog that are part of the course syllabus. The final mark takes into account the results both in the written and the oral parts as a whole and not as an average. An optional short assignment is available. It is an individual project, assigned mid-December, to be handed in for evaluation before the oral exam and no later than the end of February exam session. It entails max 2/30 bonus on the final mark. Texts of past exams and solutions are available on the website. Modes: two identical modes are foreseen: online and blended online/onsite. In the online mode, the written exam is on-paper under videosurveillance of the lecturer. The video conferencing application is Virtual Classroom, available on the course site. Requirements: personal computer with webcam or tablet, printer/scanner, browser, adequate access to the network, blank paper sheets, pen/pencil. Preliminaries • the student must show his/her identification document and this will be compared with the student’s photo available in the database of the University; • a witness (who is not a member of the Board of Examiners) will be present during the exam; • the student must declare that he/she is not using any aid or support tool and that nobody is in the room to help him/her during the exam. Written exam: • the student receives the exam text by email and prints it • the student takes the exam in front of a webcam • the student must clear the desk of all objects and the PC must be placed at a security distance • at the end of the exam, the student must show his/her paper in front of the webcam and send a scanned copy (clearly legible) together with a copy of his/her identification document. Oral exam: the student joins the Virtual Classroom when invited. In the blended online/onsite mode, some students are in a classroom, other students work in remote, the exam being identical.