Electronics - PHYS 2371/2. Wednesday, Nov 30 Exam on: Magnetoelectronics, Optoelectronics and Digital Electronics (weeks VIII to XIII) - PDF

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Wednesday, Nov 30 Exam on: Magnetoelectronics, Optoelectronics and Digital Electronics (weeks VIII to XIII) Digital Circuits Inside Computers Very large-scale integration (VLSI) CPU, central processing
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Wednesday, Nov 30 Exam on: Magnetoelectronics, Optoelectronics and Digital Electronics (weeks VIII to XIII) Digital Circuits Inside Computers Very large-scale integration (VLSI) CPU, central processing unit 10 9 transistors (Minecraft computer) Moore s Law (technology) Number of transistors, storage bits, etc. exponential growth, 2x every months Truth Table Output for each miniterm (=1) Karnaugh Map (simplification ) graphical matrix solution combine groups of miniterms (yellow) wrap around sides to combine (blue) use a miniterm more than once (orange) RULE-1: Order top/side table axes, vary only one bit when moving to next cell RULE-2: group even numbers of 1 s that are adjacent (You can wrap around the cylinder, as in AB=10 CD=00) RULE-3: Each group is one miniterm RULE-4: If input is both 0 and 1 you don t need that input Truth Table Row A B C D Out AB CD K-map Simplification Truth Table Today Electronic Clocks require pulsed ICs - Digital Watches - 1 MHz crystal divided down to 1 Hz - All Computers need to synchronize gate operations (GHz) Digital Pulsed ICs One-Shot, Oscillator, Ch one-shot timer/oscillator Flip-Flops, Ch-21 - RS flip-flops - D flip-flop (D latch) - T flip-flop - JK flip-flop (toggle) Registers and Counters, Ch-24 - binary counter 7-segment Display, Ch decoder/driver - numeral LED display Lab-11, Flip-Flip and Counter Computer Speed Clock Speed Also called clock rate, the speed at which a microprocessor executes instructions. Every computer contains an internal clock that regulates the rate at which instructions are executed and synchronizes all the various computer components. The CPU (central processing unit) requires a fixed number of clock ticks (or clock cycles) to execute each instruction. The faster the clock, the more instructions the CPU can execute. Internal architecture - effects a CPU's performance, so two CPUs with the same clock speed will not necessarily perform equally. Parallel Bits - Whereas an Intel (16-bit) microprocessor requires 20 cycles to multiply two numbers, an Intel (32-bit) performs the same calculation in a single clock tick Intel MHz GHz Now 3 GHz Multicore - Also, increasing the number of cores operating in parallel increases computation speed. (dual core, or quad core). Computer Speed Instructions per Second (IPS) Computer speed can be measured in IPS or MIPS (million IPS) or MOPS (M operations PS) 2016 Intel i7 CPU 317,900 MIPS at 3.0 GHz 300 billion instructions/second Floating point number e.g IPS ~ 1 FLOPS FLOPS better measure of speed In computing, FLOPS (for FLoating-point Operations Per Second) is a measure of computer performance, useful in fields of scientific calculations that make heavy use of floating-point calculations. For such cases it is a more accurate measure than the generic IPS. Supercomputer 93 PFLOPS IBM Roadrunner 1 PFLOPS 19,000 processors 296 computer racks 2.4 MW power $100M 2016: Sunway TaihuLight operates at 93 petaflops. Pulsed Digital ICs We will now investigate the following pulsed ICs: Multivibrators Create Pulses One-Shot 555 Timer/Oscillator Flip-Flops Use Pulses RS Flip-Flop D Flip-Flop T Flip-Flop (toggle) JK Flip-Flop (universal) Number Display BCD Decoder/Driver 7-segment LED display 74121 One-Shot (Monostable Multivibrator) Electronics - PHYS 2371/ One-Shot Use: lengthen a pulse to a preset time. Example: Lengthen a 50 ns TTL pulse to light an LED. Turning on an LED for only 50 ns would be nearly invisible. Input triggers: A1, A2 edge triggers B level trigger Q output τ(s) =0.693 R(Ω)C(F) R=140 kω, C=10 μf τ = 1 s Stretch 50 ns 1 s A1 A2 B Q 50ns +5 V t =1 s t +5 V R C +5 V Q 5 B A1 A 555 as Monostable Multivibrator (one-shot) 555 as a One-Shot Use: lengthen a pulse to a preset time. Stretch 50 ns 1 s Trigger Trigger (pin 2) is pulled HIGH when the switch is closed τ(s) = ln(3) R(Ω)C(F) =1.1RC R=100 kω, C=10 μf τ = 1.1 s 555 as Astable Multivibrator (oscillator) 555 as an Oscillator Triggers itself 555 Tutorial C 1 charges up from 1/3 V cc to 2/3 V cc Charge to t 1 =0.693 (R 1 +R 2 )C 1 At 2/3 V cc discharge t 2 =0.693 R 2 C 1 On time: t 1 =0.693 (R 1 +R 2 )C 1 Off time: t 2 =0.693 R 2 C 1 Period: T=t 1 +t 2 =0.693(R 1 +2R 2 )C 1 Frequency: f=1.44/[(r 1 +2R 2 )C 1 ] Duty Cycle: on time/period D = R 1 /(R 1 +2R 2 ) Example Flash an LED on for 0.1 s every second For t off t on, add diode across R 2 Then on time = t 1 = R 1 C Off time = t 2 = R 2 C For C=10 μf R 1 =14.4 kω, R 2 =130 k Ω * Vary components in a running oscillator Digital ICs that use Pulses ICs that use pulses - Flip-Flops and Counters Before, we had digital voltages that were more or less constant in time. When sending digital information, or performing computations, you need a train of digital pulses. Sequential Logic Computers operate by performing logic operations (AND/OR/NOT) sequentially in time. There is a socalled clock-rate that usually runs at GHz pulse rates. Thus, logic gate operations change every nanosecond. And 64 operations (64-bit) can be performed at one time (Parallel Logic). Flip-Flop Types Flip-flops are heavily used for digital data storage and transfer and are commonly used in banks called registers for the storage of binary numerical data. 1 or 2 inputs 2 outputs Q and Q See: Flip-flop (electronics) (wiki) Flip-Flops (you will use one in the last lab) What is a Flip-Flop? Flip-flop is the common name given to two-state devices which offer basic memory for sequential logic operations. Two outputs, two stable states Outputs (Q, Q), (Q=1 or 0) Bistable Multivibrator Also called a Latch, pulse sets Q and it remains there Why Flip-Flips? Basic building blocks of all memory, counters, binary math RS Flip-Flop S=Set Q=1, Q=0 R=Reset Q=0, Q=1 set or reset the output Q The first electronic flip-flop was invented in 1918 by William Eccles and F. W. Jordan. It consisted of two active elements (vacuum tubes). RS Flip-Flop Example: RS Flip-Flop S=Set, R=Reset Uses positive-going pulses Equivalent to 2 NORs NOR - any 1 gives a 0 A B OR NOR RS Flip-Flop with pulse input R S new Q new Q 0 0 nc set reset 1 1?? nc = no change (last value) See how an RS FF switches (wiki) Feedback maintains output values constant RS Flip-Flop Example: RS Flip-Flop S=Set, R=Reset Uses negative-going pulses Equivalent to 2 NANDs NAND - any 0 gives a 1 A B AND NAND RS Flip-Flop with pulse input S R new Q new Q 1 1 nc (set) (reset) 0 0?? nc = no change (last value) Summary: RS and RS Flip-Flops RS Flip-Flop Uses positive-going pulses Equivalent to 2 NORs Any 1 gives a 0 RS Flip-Flop Uses negative-going pulses Equivalent to 2 NANDs Any 0 gives a 1 Don t get confused about the RS or RS notation. RS refers to a positive-going pulse. RS refers to a negative-going pulse. Most people simple drop the (NOT) bars and assume either positive-going or negative-going pulses. Clocked Flip-Flop Clock Pulse Notation Clock = CK = CLK = CP also called Enable/Triggered Clock pulse enables inputs Nothing changes unless there is a clock pulse CLK = 0 no change in outputs CLK = 1 new RS changes output D Latch Value Enabled D latch Only one input = D plus enable = E The D Latch captures the value of the D-input whenever enable is on, E=1. That captured value becomes the Q output. At other times, the output Q does not change. Value Enabled Depends on the value of E * D-latch and Flip-Flop (0-4:53, shows timing), 15:42 Value Enabled Clocked D Flip-Flop Only one input = D plus clock pulse = CLK By far the most important FF Stores one input (MEMORY) Electronics - PHYS 2371/2 D Flip-Flop Edge Triggered The D flip-flop captures the value of the D-input at a definite portion of the clock cycle (such as the rising edge of the clock). Edge Triggering That captured value becomes the Q output. At other times, the output Q does not change. The D flip-flop can be viewed as a memory cell, a zero-order hold, or a delay line. Edge Triggering * Watch: D-latch and Flip-Flop (4:54+), 15:42 Enabling/Triggering Flip-Flops D Latch value enabled D Flip-Flop edge triggered Value Enabling Edge triggering T Flip-Flop: TOGGLE (use in last lab) Clocked T Flip-Flop: TOGGLE Only one input = T plus clock pulse = CP If the T input is high, the T flip-flop changes state ( toggles ) whenever the clock input is strobed. Simply Q Q If the T input is low, the flip-flop holds the previous value. This behavior is described by: Q next = T Q + T Q * Watch: JK and T Flip-Flop, (8:15-9:15) 13:09 JK Flip-Flop JK Flip-Flip Most powerful Can be configured as RS-FF, D-FF, T-FF The JK flip-flop augments the behavior of the SR flip-flop by interpreting J=Set and K=Reset. Q 0 goes into Q next The combination J=1, K=0 is a command to set the flip-flop (Q next =1) The combination J=0, K=1 is a command to reset the flip-flop (Q next =0) JK Flip-Flop J K CLK Qnext 0 0 Q 0 hold set reset 1 1 Q 0 toggle The combination J=K=1 is a command to toggle the flip-flop (Q 0 Q 0 ) On the CLK edge, Q 0 is set to Q next =Q 0. Q next = J Q 0 + K Q 0 Watch on your own: JK and T Flip-Flop, 13:09 Toggle from JK Flip-Flop Make JK-FF into simple Toggle Set J=K=1 Each time a clock pulse edge comes, the output is toggled. Q Q Q Q Q Use toggle from JK flip flop as a binary counter Binary Counter, Ch. 24 * Watch: Binary Counter, 20 sec Binary Counter Counts how many clock pulses come by See: Binary Counter details, 10 min Note falling edge triggering with delay Use the JK-FF in TOGGLE mode Binary Number DCBA D C B A Q 2 Q 1 Q 0 CLK FF2 FF1 FF0 CLK Note: A is the least significant bit in DCBA (e.g. 0101) * Watch: Binary Counter, 20 sec Lab-11 Flip-Flop, Counters, Displays Design and construct a binary counter circuit using JK flip-flops The circuit cycles through the binary numbers Convert binary numbers to BCD Light LED digital number display Square wave generator Combine flip flops SN74LS47N BCD-to-seven-segment decoder/driver LTS-4801B 7-segment LED for digits 0-9 Lab-11, Roll the Dice Make 4-bit Counter Three JK-FF +5V Q J Q J Q J CP CP CP Q K Q K Q K C B A SN74LS47N BCD-to-seven-segment common anode decoder/driver R x =200 or 400 Ω LTS-4801B 7-segment LED for digits 0-9 common anode * See Decoder/Display Note: A is the least significant bit (CBA) Lab-11 Eliminate 0, so that it does not appear Square wave generator 7-Segment LED? After you make the circuit that displays the numbers 0-7, design a modified circuit that eliminates the number zero from displaying. Wednesday, November 30 Last Exam: on Magnetoelectronics, Optoelectronics, and Digital Electronics For questions, /visit me or TA mwisho
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