# CSCE 212 Computer Architecture - Computer Science & E

CSCE 211 Digital Design Lec 11 Flip Flop Excitation Tables Topics Sequential Circuits SR Latch Clocked SR Master Slave Master Slave VHDL Readings: 5.4, 5.9, 5.10, 4.4 1 October 21, 2015

CSCE 211H Fall 2015 Overview Last Time Sequential Circuits: Basic Nor Latch New Sequential Circuits Clocked SR flip flops

Master Slave SR VHDL two bit adder Arduino 2 Kits http://www.arduino.cc/ ; http://arduino.cc/en/Guide/HomePage

CSCE 211H Fall 2015 Register Bank - Mux ALU - Decoder 3 CSCE 211H Fall 2015 Clocked SR-Latch http://www.play-hookey.com/digital/ S1 R1 4 CSCE 211H Fall 2015 http://www.play-hookey.com/digital/sequential/clocked_rs_latch.html

S1 State Table SR clocked Flip-flop Clk S R R1 Q S1 R1 Q*

(next) 0 1 0 0 0 1 0 0 1

1 0 1 0 1 0 1 1 1 1

0 0 1 1 0 1 1 1 1

0 1 1 1 1 5 CSCE 211H Fall 2015 Clocked SR-Latch Implementation S Q

CP Qbar R 74LS00 6 CSCE 211H Fall 2015 74 LS10 7 CSCE 211H Fall 2015 Building a JK from Chips 74LS00 Vcc

74LS10 CP Q J QN K 74LS00 GND 8 CSCE 211H Fall 2015

74LS49 Seven segment display driver 74LS49/74LS47 Inputs BCD digit (DCBA) (D is the MSB) Outputs abcdefg the seven segment driver lines Schematic fig 5-45 Note negation of inputs to or-gate x + y = (x + y) = (x . y) = (x . y) Its a NAND!

9 Truth table fig 5-21 CSCE 211H Fall 2015 Hints on Circuits Hook up MUX BCD-to-7Seg 7Segment Steps 1. Vcc,GND to all 2. put 330 ohm resistors in series with anode connections to LSD5061-11 (MAN71A) hooking them to Vcc 3. Test the 7-segment display hooking the individual cathodes to GND 4. Hook up outputs from 74LS47 to cathode inputs of 7-segment display 5. Hook the LampTest (pin 3) of the 74LS47 to GND, all segments should light up. 6. Hook up A1,A0 inputs of 74LS47 to Mux outputs, A2 and A3

should be GND 7. Test various values of select lines and mux inputs 10 CSCE 211H Fall 2015 Arduino kits 11 CSCE 211H Fall 2015 Getting Started with Arduino Introduction: What Arduino is and why you'd want to use it. Installation: Step-by-step instructions for setting up the Arduino software and connecting it to an Arduino Uno, Mega2560, Duemilanove, Mega, or Diecimila.

Windows Mac OS X Linux (on the playground wiki) Environment: Description of the Arduino development environment and how to change the default language. Libraries: Using and installing Arduino libraries. Troubleshooting: Advice on what to do if things don't work. 12 http://arduino.cc/en/Guide/HomePage

CSCE 211H Fall 2015 Installing Arduino on Linux 13 CSCE 211H Fall 2015 Teams? 10 People; 5 teams 14 CSCE 211H Fall 2015 Seven segment Display 15

CSCE 211H Fall 2015 74LS47 BCD to Seven Seg. Driver 16 CSCE 211H Fall 2015 74LS153 Dual 4 input MUX 17 CSCE 211H Fall 2015 74LS153 74LS47 74LS153

Hooking them Up 18 CSCE 211H Fall 2015 Transition Table for Clocked SR flip-flop 19 S R Q(t) 0 0

0 0 0 1 0 0 1 1 0 1 1 1

0 0 0 1 1 1 1 1 0 1 Q* or Q(t+1) CSCE 211H Fall 2015

J-K Flip Flop J K http://www.play-hookey.com/digital/jk_nand_flip-flop.html 20 CSCE 211H Fall 2015 Transition Table for JK Flip Flop 21 J K Q(t)

0 0 0 0 0 1 0 0 1 1 0 1

1 1 0 0 0 1 1 1 1 1 0 1 Q* or Q(t+1)

CSCE 211H Fall 2015 The D Flip Flop One input D D = 0 Q(t+1) = 0 D = 1 Q(t+1) = 1 22 CSCE 211H Fall 2015 The T Flip Flop One input T T = 0 No change Q(t+1) = Q(t) T = 1 Complement Q(t+1) = Q(t)

23 CSCE 211H Fall 2015 Excitation Tables What inputs do we need to supply to the flip-flop do achieve the desired state transition? 24 Q(t) Q(t+1) 0 0

0 1 1 0 1 1 S R CSCE 211H Fall 2015 Excitation Tables: JK

What inputs do we need to supply to the flip-flop do achieve the desired state transition? 25 Q(t) Q(t+1) 0 0 0 1 1

0 1 1 J K CSCE 211H Fall 2015 Excitation Tables: T What inputs do we need to supply to the flip-flop do achieve the desired state transition? 26 Q(t)

Q(t+1) 0 0 0 1 1 0 1 1

J K CSCE 211H Fall 2015 Characteristic Equations Next state as a function of current state and inputs Q* = F(Q, S, R) // Q* = Q(t+1) Table 7-1 of text For MS S-R flip-flop Q* 27 CSCE 211H Fall 2015

Characteristic Tables and Equations Characteristic Tables for a flip flop Describes next state Q* [or Q(t+1)] as function of inputs and in terms of current state Q [or Q(t)] Characteristic Equation specifies the next state as a function of current state and inputs (as an equation) 28 CSCE 211H Fall 2015 Table 7-1 Characteristic Equations Device Characteristic Equation S-R Latch Q* = S + R Q

D-latch Q* = D D flip-flop with Enable Q* = EN . D + EN . Q Master-Slave SR flip-flop Master-Slave JK Edge Triggered JK T flip-flop T with Enable 29 CSCE 211H Fall 2015

Excitation Tables What inputs need to be given to cause a specific state transition? 30 CSCE 211H Fall 2015 Edge Triggered D Flip-Flops Positive edge triggered master D D C Q slave

QM D Q C CLK Suppose D=0 for sometime then Qm = 0 and Q = 0 Then tracing this through setting D=1, CLK=1 The master changes when the clock CLK goes to 0 This means QM goes to 1, and then when the CLK goes to 1 Q becomes 1 CSCE 211H Fall 2015 31 State-machine structure (Mealy)

output depends on state and input typically edge-triggered D flip-flops 32 CSCE 211H Fall 2015 State-machine structure (Moore) output depends on state only typically edge-triggered D flip-flops 33 CSCE 211H Fall 2015

TBird Lights State machine problem 34 CSCE 211H Fall 2015 TBird Lights 35 CSCE 211H Fall 2015 36 CSCE 211H Fall 2015 Bouncing Switches Connecting the red terminals below should change

the output from 0 to 1. However, this change is not instantaneous; switches bounce http://www.ganssle.com/debouncing.pdf 37 CSCE 211H Fall 2015 Switch Bouncing When contact is made, it is not made instantaneously and smoothly. There is contact, it bounces open, contact again, open again finally settling down after a few milliseconds (840 sec = 840*10-6 sec) 38 http://www.ganssle.com/debouncing.pdf CSCE 211H Fall 2015

Debouncing with a SR latch Fig 8-6 p 669 39 CSCE 211H Fall 2015

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