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INSIDE THECOMPUTER Registers¾The CPU uses registers to storeinformation temporarily Values to be processed Address of value to be fetched from memoryInside CPUs¾In general, the more and bigger theregisters, the better the CPU Registers can be 8-, 16-, 32-, or 64-bit The disadvantage of more and bigger registersis the increased cost of such a CPUHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN29

Program CounterInside CPUsInstruction RegisterFlagsALUInstruction decoder,timing, and controlInternalbusesRegister ARegister BControl Bus Data Bus(cont’)Address BusINSIDE THECOMPUTERRegister CRegister DHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN30

INSIDE THECOMPUTERInside CPUs(cont’) ALU (arithmetic/logic unit)¾ Performs arithmetic functions such as add,subtract, multiply, and divide, and logicfunctions such as AND, OR, and NOTProgram counter¾Points to the address of the nextinstruction to be executed As each instruction is executed, the programcounter is incremented to point to the addressof the next instruction to be executed Instruction decoder¾Interprets the instruction fetched into theCPU A CPU capable of understanding moreinstructions requires more transistors to designHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN31

INSIDE THECOMPUTERInternalWorking ofComputersEx. A CPU has registers A, B, C, and D and it has an 8-bitdata bus and a 16-bit address bus. The CPU can accessmemory from addresses 0000 to FFFFHAssume that the code for the CPU to move a value toregister A is B0H and the code for adding a value toregister A is 04HThe action to be performed by the CPU is to put 21H intoregister A, and then add to register A values 42H and 12H.HANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN32

INSIDE THECOMPUTERInternalWorking ofComputers(cont’)Ex. (cont’)ActionCodeDataMove value 21H into reg. AAdd value 42H to reg. AAdd value 12H to reg. AB0H04H04H21H42H12HMem. addr.1400140114021403140414051406Contents of memory address(B0) code for moving a value to register A(21) value to be moved(04) code for adding a value to register A(42) value to be added(04) code for adding a value to register A(12) value to be added(F4) code for halt.HANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN33

Ex. (cont’)The actions performed by CPU are as follows:1. The program counter is set to the value 1400H,indicating the address of the first instruction code tobe executedINSIDE THECOMPUTERInternalWorking ofComputers2.¾(cont’)The CPU puts 1400H on address bus and sends itout ¾以動畫表示The memory circuitry finds the locationThe CPU activates the READ signal, indicating tomemory that it wants the byte at location 1400H This causes the contents of memory location1400H, which is B0, to be put on the data bus andbrought into the CPU.HANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN34

INSIDE THECOMPUTEREx. (cont’)3.¾¾InternalWorking ofComputersThe CPU decodes the instruction B0The CPU commands its controller circuitry to bringinto register A of the CPU the byte in the nextmemory location (cont’)¾The value 21H goes into register AThe program counter points to the address of thenext instruction to be executed, which is 1402H Address 1402 is sent out on the address bus tofetch the next instruction.HANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN35

INSIDE THECOMPUTEREx. (cont’)4.¾¾InternalWorking ofComputers¾(cont’)From memory location 1402H it fetches code 04HAfter decoding, the CPU knows that it must add tothe contents of register A the byte sitting at thenext address (1403)After the CPU brings the value (42H), it providesthe contents of register A along with this value tothe ALU to perform the addition It then takes the result of the addition from theALU’s output and puts it in register AThe program counter becomes 1404, the addressof the next instruction.HANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN36

INSIDE THECOMPUTEREx. (cont’)5.¾InternalWorking ofComputers(cont’) This code is again adding a value to register AThe program counter is updated to 1406H6.¾¾HANELAddress 1404H is put on the address bus and thecode is fetched into the CPU, decoded, andexecutedThe contents of address 1406 are fetched in andexecutedThis HALT instruction tells the CPU to stopincrementing the program counter and asking forthe next instructionDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN37

8051 MICROCONTROLLERSThe 8051 Microcontroller and EmbeddedSystems: Using Assembly and CMazidi, Mazidi and McKinlayChung-Ping Young楊中平Home Automation, Networking, and Entertainment LabDept. of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN

OUTLINES HANELMicrocontrollers and embeddedprocessorsOverview of the 8051 familyDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN2

ervs. GeneralPurposeMicroprocessor General-purpose microprocessorscontains¾¾¾ Microcontroller has¾¾¾¾¾¾HANELNo RAMNo ROMNo I/O portsCPU (microprocessor)RAMROMI/O portsTimerADC and other peripheralsDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN3

ervs. eMicroProcessorData busRAMTimerSerialCOMPortCPUAddress SerialCOMPortDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN4

ervs. GeneralPurposeMicroprocessor General-purpose microprocessors¾¾¾ Microcontroller¾(cont’)¾HANELMust add RAM, ROM, I/O ports, andtimers externally to make them functionalMake the system bulkier and much moreexpensiveHave the advantage of versatility on theamount of RAM, ROM, and I/O portsThe fixed amount of on-chip ROM, RAM,and number of I/O ports makes them idealfor many applications in which cost andspace are criticalIn many applications, the space it takes,the power it consumes, and the price perunit are much more critical considerationsthan the computing powerDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN5

ersfor EmbeddedSystems An embedded product uses amicroprocessor (or microcontroller) todo one task and one task only¾ There is only one application software thatis typically burned into ROMA PC, in contrast with the embeddedsystem, can be used for any number ofapplications¾¾It has RAM memory and an operatingsystem that loads a variety of applicationsinto RAM and lets the CPU run themA PC contains or is connected to variousembedded products Each one peripheral has a microcontroller insideit that performs only one taskHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN6

ersfor EmbeddedSystems Home¾ Office¾(cont’) Telephones, computers, security systems, faxmachines, microwave, copier, laser printer, colorprinter, pagingAuto¾HANELAppliances, intercom, telephones, security systems,garage door openers, answering machines, faxmachines, home computers, TVs, cable TV tuner,VCR, camcorder, remote controls, video games,cellular phones, musical instruments, sewingmachines, lighting control, paging, camera, pinballmachines, toys, exercise equipmentTrip computer, engine control, air bag, ABS,instrumentation, security system, transmissioncontrol, entertainment, climate control, cellularphone, keyless entryDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN7

MICROCONTROLLERSANDEMBEDDEDPROCESSORSx86 PCEmbeddedApplications ¾ HANELMany manufactures of general-purposemicroprocessors have targeted theirmicroprocessor for the high end of theembedded marketThere are times that a microcontroller isinadequate for the taskWhen a company targets a generalpurpose microprocessor for theembedded market, it optimizes theprocessor used for embedded systemsVery often the terms embeddedprocessor and microcontroller are usedinterchangeablyDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN8

MICROCONTROLLERSANDEMBEDDEDPROCESSORSx86 PCEmbeddedApplications(cont’) One of the most critical needs of anembedded system is to decreasepower consumption and spaceIn high-performance embeddedprocessors, the trend is to integratemore functions on the CPU chip and letdesigner decide which features he/shewants to useIn many cases using x86 PCs for thehigh-end embedded applications¾Saves money and shortens developmenttime A vast library of software already written Windows is a widely used and well understoodplatformHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN9

MICROCONTROLLERSANDEMBEDDEDPROCESSORSChoosing aMicrocontrollerHANEL 8-bit microcontrollers¾¾¾¾ Motorola’s 6811Intel’s 8051Zilog’s Z8Microchip’s PICThere are also 16-bit and 32-bitmicrocontrollers made by various chipmakersDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN10

MICROCONTROLLERSANDEMBEDDEDPROCESSORSCriteria forChoosing aMicrocontroller Meeting the computing needs of thetask at hand efficiently and wer consumptionThe amount of RAM and ROM on chipThe number of I/O pins and the timer onchipHow easy to upgrade to higherperformance or lower power-consumptionversionsCost per unitDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN11

MICROCONTROLLERSANDEMBEDDEDPROCESSORS Availability of software developmenttools, such as compilers, assemblers,and debuggersWide availability and reliable sourcesof the microcontroller¾Criteria forChoosing aMicrocontroller(cont’)HANELThe 8051 family has the largest number ofdiversified (multiple source) suppliers Intel (original)AtmelPhilips/SigneticsAMDInfineon (formerly Siemens)MatraDallas Semiconductor/MaximDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN12

OVERVIEW OF8051 FAMILY¾The 8051 is an 8-bit processor The CPU can work on only 8 bits of data at atime8051Microcontroller¾The 8051 had HANELIntel introduced 8051, referred as MCS51, in 1981128 bytes of RAM4K bytes of on-chip ROMTwo timersOne serial portFour I/O ports, each 8 bits wide6 interrupt sourcesThe 8051 became widely popular afterallowing other manufactures to makeand market any flavor of the 8051, butremaining code-compatibleDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN13

pROMfor codeOn-chipRAMEtc.Timer 0Timer 1BusControlI/OPortsSerialPortCounter InputsOVERVIEW OF8051 FAMILYExternalInterruptsCPUOSCP0 P1 P2 P3TXDRXDAddress/DataHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN14

OVERVIEW OF8051 FAMILY The 8051 is a subset of the 8052The 8031 is a ROM-less 8051¾8051 Family¾Add external ROM to itYou lose two ports, and leave only 2 portsfor I/O operationsFeatureROM (on-chip programspace in bytes)4K8K0K128256128Timers232I/O pins323232Serial port111Interrupt sources686RAM (bytes)HANEL8051 8052 8031Department of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN15

OVERVIEW OF8051 FAMILYVarious 8051Microcontrollers 8751 microcontroller¾UV-EPROM PROM burner UV-EPROM eraser takes 20 min to erase AT89C51 from Atmel Corporation¾Flash (erase before write) ROM burner that supports flash A separate eraser is not needed DS89C4x0 from Dallas Semiconductor,now part of Maxim Corp.¾Flash Comes with on-chip loader, loading program toon-chip flash via PC COM portHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN16

OVERVIEW OF8051 FAMILYVarious 8051Microcontrollers DS5000 from Dallas Semiconductor¾ Also comes with on-chip loader (cont’) OTP (one-time-programmable) versionof 80518051 family from Philips¾HANELNV-RAM (changed one byte at a time),RTC (real-time clock)ADC, DAC, extended I/O, and both OTPand flashDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN17

8051 ASSEMBLYLANGUAGEPROGRAMMINGThe 8051 Microcontroller and EmbeddedSystems: Using Assembly and CMazidi, Mazidi and McKinlayChung-Ping Young楊中平Home Automation, Networking, and Entertainment LabDept. of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN

INSIDE THE8051 RegistersRegister are used to store informationtemporarily, while the informationcould be¾¾ The vast majority of 8051 register are8-bit registers¾HANELa byte of data to be processed, oran address pointing to the data to befetchedThere is only one data type, 8 bitsDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN2

INSIDE THE8051 The 8 bits of a register are shown fromMSB D7 to the LSB D0¾Registers(cont’)With an 8-bit data type, any data largerthan 8 bits must be broken into 8-bitchunks before it is processedmostsignificant bitD7D6D5D4leastsignificant bitD3D2D1D08 bit RegistersHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN3

INSIDE THE8051Registers(cont’) The most widely used registers¾A (Accumulator) For all arithmetic and logic instructions¾¾B, R0, R1, R2, R3, R4, R5, R6, R7DPTR (data pointer), and PC LPC (Program counter)Department of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN4

INSIDE THE8051MOV destination, source¾The instruction tells the CPU to move (in reality,COPY) the source operand to the destinationoperandMOVInstructionHANEL;copy source to dest.“#” signifies that it is a R3;load value 55H into reg. A;copy contents of A into R0;(now A R0 55H);copy contents of A into R1;(now A R0 R1 55H);copy contents of A into R2;(now A R0 R1 R2 55H);load value 95H into R3;(now R3 95H);copy contents of R3 into A;now A R3 95HDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN5

INSIDE THE8051MOVInstruction(cont’) Notes on programming¾Value (proceeded with #) can be loadeddirectly to registers A, B, or R0 – R7 MOV A, #23H MOV R5, #0F9HAdd a 0 to indicate thatF is a hex number andnot a letter¾If it’s not preceded with #,it means to load from amemory locationIf values 0 to F moved into an 8-bitregister, the rest of the bits are assumedall zeros “MOV A, #5”, the result will be A 05; i.e., A 00000101 in binary¾Moving a value that is too large into aregister will cause an error MOVHANELA, #7F2H ; ILLEGAL: 7F2H 8 bits (FFH)Department of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN6

ADD A, sourceINSIDE THE8051¾ADDInstruction¾;ADD the source operand;to the accumulatorThe ADD instruction tells the CPU to add the sourcebyte to register A and put the result in register ASource operand can be either a register orimmediate data, but the destination must alwaysbe register A “ADD R4, A” and “ADD R2, #12H” are invalidsince A must be the destination of any arithmeticoperationThere are alwaysmany ways to writethe same program,depending on theregisters usedHANELMOV A, #25H;load 25H into AMOV R2, #34H;load 34H into R2ADD A, R2 ;add R2 to Accumulator;(A A R2)MOV A, #25H;load one operand;into A (A 25H)ADD A, #34H;add the second;operand 34H to ADepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN7

8051ASSEMBLYPROGRAMMINGStructure ofAssemblyLanguage In the early days of the computer,programmers coded in machine language,consisting of 0s and 1s¾ Tedious, slow and prone to errorAssembly languages, which providedmnemonics for the machine code instructions,plus other features, were developed¾ An Assembly language program consist of a seriesof lines of Assembly language instructionsAssembly language is referred to as a low-level language¾HANELIt deals directly with the internal structure of theCPUDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN8

8051ASSEMBLYPROGRAMMINGStructure ofAssemblyLanguageAssembly language instruction includes¾a mnemonic (abbreviation easy to remember) the commands to the CPU, telling it what thoseto do with those items¾optionally followed by one or two operands the data items being manipulated A given Assembly language program isa series of statements, or lines¾Assembly language instructions Tell the CPU what to do¾Directives (or pseudo-instructions) Give directions to the assemblerHANELDepartment of Computer Science and Information EngineeringNational Cheng Kung University, TAIWAN9

8051ASSEMBLYPROGRAMMINGStructure ofAssemblyLanguageMnemonicsproduceopcodes An Assembly language instructionconsists of four fields:[label:] Mnemonic [operands] [;comment]ORG0MOVMOVMOVADD0HADDA, R7ADDA, #12HR5, #25HR7, #34HA, #0A, R5HERE: SJMP HEREEND;start(origin) at location;load 25H into R5;load 34H intoR7Directivesdo not;load 0 into generateAany machineused;add contentscodeofandR5aretoA;now A A onlyR5 by the assembler;add contents of R7 to A;now A A R7;add to A value 12H;now A A

The 8051 Microcontroller and Embedded Systems Using Assembly and C Second Edition Muhammad Ali Mazidi Janice Gillispie Mazidi Rolin D. McKinlay CONTENTS Introduction to Computing The 8051 Microcontrollers 8051 Assembly Language Programming Branc