Using LogicWorksGetting StartedWhat is LogicWorks?Important…Today’s outlineInterfaceInterface (2)Interface (3)Interface (4)Interface (5)Interface (6)Interface (7)Working with devicesWorking with devices (2)Input and OutputInput and Output (2)DebuggingUniversity of Illinois at Urbana Champaign1Using LogicWorksCS 231 – Fall 2007Sept 14, 2007Slides adadpted from Sang Kim, Spring 2007University of Illinois at Urbana Champaign2Getting StartedLogicWorks 4.1Avaliable in EWS LabsDigital Computer Lab Rm. L426Engineering Hall Rm. 406B8http://www.ews.uiuc.edu/labs/University of Illinois at Urbana Champaign3What is LogicWorks?A software that allows simulation of hardware components and their interactions.Advantages of using a simulatorCostTimeUniversity of Illinois at Urbana Champaign4Important…4 HWs (e.g. HW 3,5,8,10) will contain LogicWorks problem. Make sure to know how to use LogicWorks yourself.Be neat and organized!Use labels on pins, instead of crossing wires everywhereTypically, data flows from left to right.(Except in our datapath, where it flowsup down up)University of Illinois at Urbana Champaign5Today’s outlineInterfaceWorking with devicesInput and outputDebuggingUniversity of Illinois at Urbana Champaign6InterfaceMain layout screenParts of list palette (can tear off) Simulation Gates: and, or, not, ... Simulation IO: binary switch, hex keyboard, binary probe, hex display Simulation Logic: adder, clock, flip-flop, decoder, mux double click device in parts palette single click in layout to place deviceUniversity of Illinois at Urbana Champaign7Interface (2)Timing diagram Can be accessed underView Timing WindowFor sequential circuits (HW8 & 10) Shows clock and signals over timeZoom in and out using toolbarUniversity of Illinois at Urbana Champaign8Interface (3)Drawing Toolbar Zap to delete lines & components - useful to cleanup mistakes Text tool to add labels and pin names Signal wire (1-bit) Bus wire (multi-bit)University of Illinois at Urbana Champaign9Interface (4)Simulation Toolbar For sequential circuits (HW8 & 10) Adjust simulator clock speed As alternative to using a fixed clock speed, use binary switch as "clock" and manually toggle when a clock cycle happens. Easier to verify that everything happened correctly.University of Illinois at Urbana Champaign10Interface (5)File menu Open... Type: Circuits files Type: Symbol libraries (to be used later)University of Illinois at Urbana Champaign11Interface (6)Schematic menu Design Preferences Show printed page breaksMake sure components don't span page breaks Show background gridUniversity of Illinois at Urbana Champaign12Interface (7)Keyboard shortcuts Arrows make gate point left, right, up, or downContext menu (right click) Name: useful to label components in big circuits Right click tip of pin Name: to connect pins without drawing a wireUniversity of Illinois at Urbana Champaign13Working with devicesConnecting devices Naming the pins reduces the messDrag wire from one pin to another Use signal or bus tool Ends must contact — intersect is not enough! Entire wire & pins should turn yellow when selectedUniversity of Illinois at Urbana Champaign14Working with devices (2)Be careful using gates with inverters Making gates with more inputs Append the gates to each otherUse some logic BUT be careful on the implicationsE.g. AND-6: a six input AND gate Use AND-8 — What to do with remaining pins? E.g. AND-6 Use AND-3 plus AND-4 — How to connect? Don't use five AND-2 gates!University of Illinois at Urbana Champaign15Input and OutputBinary switch Enter 1 bit To move switches (and most of the other components too) hold down shift while clicking Binary probe Display 1 bit. Really useful for debugging! Z: unknown value — somewhere a pin is disconnected C: conflict value — 2 conflicting pins with same label Sometimes just need to toggle inputsUniversity of Illinois at Urbana Champaign16Input and Output (2)Hex keyboard Enter 4 bits in hex — useful for our 4 bit bus Hex display Display 4 bits in hex 7 segment display (LED) Gray if unknown — this indicates a bug! Blank (white) if 0 Solid black(or red) if 1University of Illinois at Urbana Champaign17DebuggingUse lots of binary probes Verify that pins are connectedRemember yellowVerify that correct pin names are used (spelling,
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