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digi mul ppt

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digi mul ppt

  1. 1. Project on DIGITAL MULTIMETER DESIGN (USING VHDL) Presented by: o Mohit Mukul 1104030 o Harsh Prakash Singh 1104062 o Rahul Kumar 1104063 Under the supervision of : Mr. Bibhuti Bikramaditya (TekBrains Pvt.ltd.) and Dr. Bijay Kumar Sharma Deptt. Of ECE, NITP DEPARTMENT OF ELECTRONICS & COMMUNICATION ENGINEERING, NIT PATNA
  2. 2.  Introduction  Objectives  Platforms used  Mechanism  Working parts  Work done  Conclusion  Future scope  References Phases of the project
  3. 3. 1.1 Digital Multimeter(DMM)  An electronic measuring instrument that combines several measurement functions in one unit, viz. voltage, current, resistance, beta of the transistors, etc.  Display the measured value in numerals  More common than the analog multimeters.  The signal under test is converted into voltage and an amplifier with electronically controlled gain preconditions the signal. Introduction
  4. 4. 1.2 VHDL  VHDL stands for VHSIC (Very High Speed Integrated Circuits) Hardware Description Language  A hardware description language which describes the behaviour of the circuit based on the logic implemented  Intended for circuit synthesis and circuit simulation  A standard, technology/vendor independent language and so is portable and reusable.  Applications in the field of Programmable logic devices(PLD’s) -- Complex Programmable Logic Devices (CPLD’s) -- Field Programmable Gate Arrays (FPGA’s) and in the field of Application Specific Integrated Circuits (ASIC’s)  Statements are concurrent i.e., executed parallely. So VHDL is sometimes also called code.  In VHDL, statements inside a PROCESS, FUNCTION and PROCEDURES are processed serially. Contd.
  5. 5. Summary of VHDL design flow: Contd.
  6. 6. 1.3 FPGA  FPGA stands for Field Programmable Gate Array is an IC designed to be configured by a designer after manufacturing. So, Field Programmable.  Configured using a HDL  An array of programmable logic blocks which can be reconfigured  Perform complex combinational functions or simple logic gates and even include simple flip-flops Contd.
  7. 7.  To design, build and test a multimeter comparable in performance to some extent with the multimeters available at the ECE laboratories.  Use a FPGA kit to implement the logic component of our circuit (programmed via VHDL) and also for its LED and LCD displays to showcase the functionalities of our multimeter.  The basic design of the VHDL code is a system to : -- Control the flow of the following states- Reset/Display, Count- Up, Set-Sign, Countdown and Binary-BCD Decoding -- Manipulate the four registers to fluctuate between the ohmmeter, voltmeter, ammeter and the Beta calculations. -- Use the LCD drivers to signal the current state. Objective
  8. 8.  Xilinx Vivado 2014.1  ModelSim SE 6.2g (Mentor Graphics)  Xilinx SDK 2014.1  Windows 7 Platforms used
  9. 9. Modes of DMM: 1. Voltmeter 2. Ammeter 3. Ohmmeter 4. Beta calculator  Built by chip soldering on the Electric Circuit Board (ECB)  Run by FPGA kit, which is controlled by the VHDL code  FPGA sends the signals to the ECB contained in a black box Main parts of the DMM: 1. VHDL code 2. Power Supply 3. Voltmeter circuit 4. Ammeter circuit 5. Ohmmeter circuit 6. Beta calculator circuit 7. Metal enclosure Mechanism
  10. 10.  The FPGA is sync. with the fundamental Voltmeter circuit to perform as per the VHDL code  Voltmeter circuit is the basic circuit and serves as a platform  Ohmmeter uses the voltmeter to know the unknown R by passing a small constant current  Ammeter uses the voltmeter and a difference and inverting amplifier to find the current  Power supply steps down the AC voltage and converts it into DC. Contd.
  11. 11.  VHDL code  Power supply  Voltmeter  Ammeter  Ohmmeter  Beta calculator  Metal enclosure Working parts
  12. 12. -- serves as the brain of the DMM -- works as counters, registers, decoders, multiplexers, range checkers, drivers and state machines Modules of the VHDL code: -- up and down counters -- range check modules (not a part of the State machine) -- binary to BCD converter -- LCD driver -- 4 bit register to store the current mode VHDL code
  13. 13. States of the state machine: 1. reset/display 2. count up 3. set sign 4. count down 5. binary-bcd decoding Reset mode: 1. Resets all registers to store new BCD value for display 2. Resets the integrator by shortening the capacitor Count up mode: 1. Up counter measures a particular time(say 500ms) while Vin is enabled and passed to integrator 2. After time, counter signals to pass to next state Set sign mode: 1. Output from the voltmeter comparator is inverted and saved in a latch 2. If Vcomparator>Vg, Vin is –ve or vice versa 3. Output of latch is passed to mux to decide the Vref (+5/-5 volts) State machine
  14. 14. Count down mode: 1. Stays in this mode until Vcomparator changes from high to low or vice versa 2. Down counter is enabled to store time in binary Binary to BCD converter mode: 1. Time in binary is converter to BCD 2. Binary is used for easier computation  Working of State machine is based on the Moore’s style state principle Contd.
  15. 15. Voltmeter circuit consists of: 1. Integrating op-amp 2. Comparator 3. Multiplexer 4. Relay switches  Integrator and Comparator form the main part of the ADC  Multiplexer provides the Vref as per the sign of Vin  Relay switches are used to choose between Vin and Vref and to reset the integrator  Circuit communicates with the FPGA to work as a full voltmeter Voltmeter
  16. 16. Block diagram for voltmeter
  17. 17. Ammeter circuit consists of the following chips: 1. Difference amplifier 2. Inverting amplifier 3. Multiplexer 4. Resistors of diff. values  Difference amplifier amplifies [Vth-Vin] and is then inverted  When Vth is 0, ouptut from inverting amplifier is +ve  Multiplexer switches between diff. channels to get the output voltage in the desired range Ammeter
  18. 18. Ammeter circuit
  19. 19.  Different constant current sources for different range of the resistances  4 to 1 multiplexer to choose a range Schematic diagram of Ohmmeter circuit: Here, Re is calculated by the formula:  (5-0.7)/Re=0.00001 as Vref=5V and Vbe=0.7 V and constant current=0.01mA  Measuring the drop across the passive element and multiplying by 10000, we get the load resistance. Ohmmeter
  20. 20.  Constant base current is sent using a constant current source  Ib=0.1mA for both types npn and pnp transistors  Variable resistor is used to make accurate value of resistor  Transistor acts as current amplifier Ic= β x Ib  Voltage across the collector resistance is measured to get the Ic Beta (β) Calculator
  21. 21. Circuit diagram for β calculator
  22. 22. Written VHDL codes for the following registers and simulated and synthesized them on Xilinx. --Flip-flops --Binary-BCD converter --Latches -- Ranger checker modules --Comparators -- LCD driver --Encoders -- State machines --Decoders --Multiplexers --Demultiplexers --Counters Work done
  23. 23.  Complete replacement of analog multimeters due to: -- higher accuracy -- higher durability -- no parallax error  Modern DMM’s have a no of measurement enhancements which include: -- Auto ranging -- Auto polarity -- Sample and hold --Graphical representation of the quantity under test -- A low bandwidth oscilloscope -- Simple data acquisition features Future Scope
  24. 24.  We use VHDL to run the FPGA kit to control the different modes of DMM  Channel to these circuits is switched when button on the board is pressed  Power supply provides the various voltages to the chips in the circuits  Combining these circuits together and putting them in a black box, we build our DMM using VHDL. Conclusion
  25. 25.  "Slope (integrating) ADC." : DIGITAL-ANALOG CONVERSION. N.p., n.d. Fri. 20 Oct. 2012. <http://www.allaboutcircuits.com/vol_4/chpt_13/8.html>.  www.TekBrains.org (Bibhuti Vikramaditya)  "Www.datasheetcatalog.com." Www.datasheetcatalog.com. 21 Oct. 2012 <http://www.datasheetcatalog.org/datasheet/stmicroelectronics/1981.pdf >.  "How Analog-to-Digital Converter (ADC) Works | Hardware Secrets." How Analog-to-Digital Converter (ADC) Works | Hardware Secrets. N.p., n.d. Sat. 21 Oct. 2012. <http://www.hardwaresecrets.com/article/How-Analog-to- Digital-Converter-ADC-Works/317/8>.  ”Current Source”. Current source From Wikipedia, the free encyclopaedia N.p. 14 Nov 2012. Retrieved 20 Nov.2012< http://en.wikipedia.org/wiki/Current_source>  www.wikipedia.org References
  26. 26. Thank you Please give us a feedback
  27. 27. Simulation
  28. 28. Code
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  39. 39. RTL synthesis diagram
  40. 40. RTL synthesis diagram
  41. 41. RTL synthesis diagram
  42. 42. RTL synthesis diagram
  43. 43. RTL synthesis diagram
  44. 44. RTL synthesis diagram
  45. 45. RTL synthesis diagram
  46. 46. RTL synthesis diagram
  47. 47. RTL synthesis diagram

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