PRESENTATION OF THE PROJECTX-FINAL LEVEL 1.

Transcription

1 Implementation of digital it frequency dividersid PRESENTATION OF THE PROJECTX-FINAL LEVEL 1.

2 Why frequency divider? Motivation widely used in daily life Time counting (electronic clocks, traffic lights, ) Events counting (counting parts on a conveyor, number of cars in self-parking area, ) Digital equipments for laboratory usage (signal generators, frequency meters, ) Computers, Video Systems, Electronic Advertising Boards, sequential logic circuits are not well represented in the curriculum and are not well assimilated/understood by students; To understand frequency dividers students must understand counters, to understand counters students must understand flip-flops, => they understand a lot of sequential circuits Frequency divider => Counters => Flip-Flops => A lot of sequential circuits must be understanding

3 What the student is going to do Project presentation This project has two parts: A. Theoretical Part Understand flip-flops and counters; Understand how to use counters as frequency dividers; B. Practical Part use dedicated di d computer programs to simulate counters and different types of frequency dividers; use breadboard and general purpose logic integrated circuits to implement and test any counter or frequency divider; use state of the art logic integrated circuits (reconfigurable circuits like CPLD or FPGA), to implement and test any counter or frequency divider;; improve their skills in handling laboratory equipment.

4 A. Theoretical Part

5 Understand flip flops A. Theoretical Part What is flip-flop, where we use? Types of flip-flops (D, T, JK) symbols, truth tables, functional equations; Flip-flop operation in synchronous mode; Flip-flop operation in asynchronous mode (important role of asynchronous inputs Clear and Preset ); Simple exercises with flip flops ( ); We are not focused on internal structures of the flip-flops!

6 Understand counters A. Theoretical Part What is a counter, where we use? Classification of counters after numeration system after counting directions after internal structures Special functions (other then counting) Terminal Count Parallel l Load Count Enable Representative (commercial) IC Counters Chips asynchronous counters (74LS93, 74LS90) synchronous counters (74LS192, 74LS193) We are not focused on internal structures of counters!

7 Design simple counters A. Theoretical Part 4-Bit Asynchronous counter made with JK Flip-Flops Counters Cascading Technique

8 What is a Frequency divider? A. Theoretical Part Frequency divider is a electronic circuit that: takes an input signal of a frequency f_in generates an output signal of a frequency f_out where K is an integer that is referred as division factor Frequency dividers are wildly used in modern electronic systems; Digital frequency dividers can be implemented with: Counters; Shift registers; Other circuits;

9 Types of Frequency dividers? A. Theoretical Part Frequency divider can have: Fixed division factor K and fixed duty-cycle ; (Usually made with asynchronous counters) Programmable division factor K and fixed duty-cycle ; (Usually made with synchronous counters) Programmable division factor K and programmable duty-cycle ; (Usually made with synchronous counters and (Usually made with synchronous counters and other supplementary logical circuits)

10 A. Theoretical Part Frequency divider with fixed K and fixed Example 1: Design process for frequency divider with K=12

11 A. Theoretical Part Frequency divider with Programmable K and fixed Example 2: Frequency divider with K=74 using two BCD counters Desired factor is translated in BCD code 74= For data inputs of units (U1) we put 4-1=0011; For data inputs of tens (U2) we put 7=0111; Borrow signal (TCD for U2) is memorized by latch and then is used to drive the load inputs (PE); Because of latch => obtained K is greater by one then programmed K!

12 B. Theoretical Knowledge Divider with Programmable K and Programmable In previous two examples: Output signal is the same with load signal; Output signal has short Low state; Duration of each logic state can not be controlled; We can control (change) only frequency division factor; In order to get access to K and, we have to improve the schematic; Main idea: Use division factor K=M for LOW state; Use different division factor K=N for HIGH state; P ll l l d d l i l h h Parallel load M and N alternatively when counter reach zero state;

13 B. Theoretical Knowledge Divider with Programmable K and Programmable Example 3

14 B. Practical Part

15 Brief description of the Practice B. Practice 1. simulate counters and frequency dividers using TINA software (or similar); 2. implement and test counters and frequency dividers on breadboard with general purpose logic IC; 3. implement and test simple counters and frequency dividers in modern digital circuits such as CPLD or FPGA; 4. Use oscilloscope to verifying different types of frequency dividers (input/output signal visualization, input/output frequency determination, input/output t t voltage levels l of each logic state) t

16 1.Simulating digital circuits (1/2) C. Practice We suggest TINA Design Suite due to the following features: - analyzing, designing, and real time testing of analog, digital, HDL, MCU, and mixed electronic circuits and their PCB layouts; - circuits are entered as schematics with an easy-to-use schematic editor; - interactive simulation: great facility for digital circuits; - powerful virtual instruments: Digital Multimeter, Digital Signal Generator, Storage Oscilloscope, Function Generator, Logic Analyzer, Signal Analyzer; - Great support from Texas Instruments; - Student Edition is free, Basic Edition is around 130EUR; We propose simulations for well chosen schematics with: - flip flops; - Binary/Decimal counters in connections with other circuits to facilitate t state t visualization of the counters; counters connected for increase the maximal number of states; - Different types of frequency dividers;

17 1.Simulating digital circuits (2/2) C. Practice

18 2. Implement circuits using breadboard C. Practice Implement and test the functionality of the divider on breadboard, using general purpose logic IC (such as 74LS93, 74LS192, )

19 3. Implement circuits using FPGA (1/6) What is FPGA? C. Practice Actual trend in the implementation of digital systems is to use reconfigurable circuits like FPGA You can configure these chips to implement custom hardware functionality without ever having to pick up a breadboard or soldering iron Advantage of FPGA (Field-Programmable Gate Array) Large number of digital circuits which can be interconnected by the end user by software means (using a configuration bitstream); Bitstream contains information on how the components should be wired together to Completely reconfigurable - instantly take on a brand new personality when you recompile a different configuration of circuitry (a new bitstream); Easy to use mature high-level design tools are available; Low cost do to the mass production;

20 3. Implement circuits using FPGA (2/6) C. Practice Design steps when working with FPGA use a computer to describe a "logic function" that you want: - draw a schematic; - create a text file describing the function (using hardware description language like VHDL or Verilog). compile the "logic function" on your computer, using a software provided by the FPGA vendor. After this step we obtain a binary file (bitstream) that can be downloaded into the FPGA. circuit configuration - connect a cable from your computer to the FPGA, and download the binary file to the FPGA; test your applications according to your specifications. in case of mistake in design, just fix your "logic function", recompile and re-download it. We can make downloads in FPGAs as many time as we need (almost no limit), it) with different functionalities every time we want.

21 3. Implement circuits using FPGA (3/6) C. Practice Why we insist on teaching FPGA? Student Perspective: - students have the feeling that they working in software; - easy to develop and test new application (even without learn a hardware description language like Verilog or VHDL); - increased chances of finding a god job; Technical advantage: - Easy to use: You can configure these chips to implement custom hardware functionality without ever having to pick up a breadboard or soldering iron ; - Large number of digital it circuits it which h can be interconnected t by the end user by software means - Completely reconfigurable: in case of mistake in design, just fix your "logic function", re-compile and re-download d it. - Low cost do to the mass production;

22 3. Implement circuits using FPGA (4/6) C. Practice We suggest: - FPGA: Spartan 3E from Xilinx - Free Software: ISEWebPack - Board: Basys 2 (69$ in academic program)

23 3. Implement circuits using FPGA (5/6) C. Practice Practical aspects: - Working with FPGA is not an easy task for beginners; - To make things easier, in each practical application, you will: - begin with one Template Project in which there are already implemented some circuits that are necessary for testing different diagrams with counters or frequency dividers Signal generator to provide the clock signal for counting under test. HexDisplay to display the state of the counter, in numeric format, on one of the four digits of the Basys2 board. BinDisplay to display the state of the counter, in binary format, using the last four LEDs of the Basys2 board. - use only schematic descriptions i of the logic circuits; i

24 3. Implement circuits using FPGA (6/6) C. Practice Example: Programmable Frequency divider implementation in FPGA

25 C. Learning Outcomes

26 Learning Outcome1 C. Final Conclusions & Final Evaluation Using computer-based simulation software and technique to design electronics systems (TOPMOST: ELIDS10); Knowledge: Skills: Competences: - Understand the advantage and disadvantage of circuits simulations; - Know how to convert an generic logic diagram into an implementable electrical diagrams using commercial logic IC. Skills for circuit simulation: - draw the electrical diagram; - choose the right type of analysis; - display electrical signals in different points of electrical diagram; - Use virtual instruments. Skills for circuit design: - understand initial technical specifications; - design the logic diagram; - convert the logic diagram into electric schematic; choose the right logic ICs, - make right allocation of internal resources of the IC to cover all components of the logic diagram; - make right ihtconnections for unused IC pins; - Simulate electronic circuits using dedicated computer programs. - Design electronic circuits using dedicated computer programs.

27 C. Final Conclusions & Final Evaluation Learning Outcome 2 Build, test and check performance of basic sequential logic circuits; Knowledge: Skills: Competences: Use Data Sheet of logic circuit Skills for build the project: - Build simple and medium - make a bill of materials; complexity circuits with general - identify the ICs needed to construct the schematic; use logic integrated circuits; - make connection between pins; - Test simple and medium Skill for test the project: complexity circuits with general - check the correct realization of the electrical use logic integrated circuits; diagram; - make right connection to signal generator and power supply; - use oscilloscope to display the input/output electrical signals.

28 C. Final Conclusions & Final Evaluation Learning Outcome 3 Implementation of logic circuits in modern logic circuits like CPLD or FPGA; Knowledge: Skills: Competences: - understand concept of reconfigurable device; - understand the advantage of reconfigurable device. Skill for design the circuits: -make new project, add new sources into project, draw the schematic of the divider; -make constrains file (specify the input/output FPGA pins); - generate configuration file; Skill for implement and test the circuits: -download d l dthe configuration i file into FPGA; -make connection to the signal generator and power supply; -make tests to verify the functionality of the circuit. - Use one dedicated software environment to implement logic circuits in FPGA; - Implement and test simple and medium logic circuit in CPLD/FPGA devices.

29 C. Final Conclusions & Final Evaluation Learning Outcome 4 Design frequency dividers; Knowledge: Skills: Competences: - deep understanding of how electronic counters works; - practicalapplications applications of the counters; - standard methodologies for design frequency dividers; - where to use an frequency divider; - understand the technical specification; - choose the rightmethod to design the logic diagram of the divider; - convert the logic diagram into an realizable electrical diagram; Design frequency dividers with different specifications.

30 C. Final Conclusions & Final Evaluation Learning Outcome 5 Use oscilloscope to verifying and testing a electronic circuits; Knowledge: Skills: Competences: Understand where and how to use oscilloscope. - make connection between grounds of power supply, FPGA board and oscilloscope; - use one channel to view the input signal and other channel to view the output signal; - make correct adjustment for time base, inputs attenuators, synchronization. Proper use of laboratory equipments.

31 Thanks for your attention!