5. Timing Diagram of a PWM Waveform | Texas Instruments MSC1210

PWM Generator

Figure 11−5. Timing Diagram of a PWM Waveform

In the timing diagram of a PWM waveform in Figure 11−5, the waveform is low for 2 ticks and high for 4 ticks. Thus, the value of PWM Period = 5 (6 ticks minus

1)and PWM Duty = 1 (2 ticks minus 1). Assuming the PPOL (PWMCON.5) bit is set, the actual length of a tick is defined by the value of USEC, or equal to the period of CLK.

Configuring the PWM generator requires that the PWM Period and PWM Duty registers be set. Both of these registers are set using the PWMLOW and PWMHI SFRs; whether the program writes to PWM Period or PWM Duty is configured by first clearing or setting PWMCON.4. When PWMSEL is clear any subsequent write to PWMLOW/HI will write to the PWM Duty register. When PWMCON.4 is set, any subsequent write to PWMLOW/HI will write to the PWM Period register. PWMLOW and PWMHI can be treated as one 16-bit register because they are adjacent SFRs.

Thus, the general process for configuring the PWM generator is as follows:

1)Configure PWMCON so that PWM mode is selected, PWMCON[2:0] = 001.

2)Set PWMCON.4 to select the PWM Duty register.

3)Write the PWM Duty − 1 value to PWMLOW and PWMHI. In the above example, PWMLOW/HI is written with the value 1 because the off period is 2 ticks long, and the value written to PWM Period is the period less 1.

4)Clear PWMCON.4 to indicate that the program will now write to PWM Peri- od.

5)PWMCON.5 must be set to either 0 or 1. If clear, the PWM Duty value (set in step 3) is the time the signal will be high. If it is set, the PWM Duty value is the time the signal will be low. PWM Duty must be less than PWM Period or the output will stay in the state defined by PWMCON.5

6)Write the PWM Period − 1 value to PWMLOW and PWMHI. The value is the total number of USEC ticks of the period of the PWM. In the above ex- ample, PWMLOW/HI is written with the value 5, because the total period is 6 ticks long, and the value written to PWM Period is the period – 1.

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Texas Instruments MSC1210 manual 5. Timing Diagram of a PWM Waveform

Contents

User’s Guide Important Notice MSC1210 Memory Organization Introduction to the MSC1210Basic Registers System Timing Addressing ModesSerial Communication Pulse Width Modulator/Tone Generator Analog-to-Digital Converter Serial Peripheral Interface SPI Additional MSC1210 Hardware Additional Resource Boot ROM Routines Additional Features in the MSC1210 Compared toClock Timing Diagram Instruction-Set Quick-Reference Guide SPI/PWM/Flash Write Timing System Timing Interrupt Control 16−1 Pin Descriptions of the MSC1210 14−2 Chapter −1. MSC1210 Block Diagram MSC1210 Description −2. Pin Configuration of the MSC1210 MSC1210 Pin-Out −1. Pin Descriptions of the MSC1210 Pin # Name Description −1 Pin Descriptions of the MSC1210 Pin # Name Description 1 I/O Ports P0, P1, P2, and P3 AD7 Port Port Oscillator Inputs XTAL1 and XTAL2 Address Latch Enable ALE Reset Line RSTProgram Store Enable Psen External Access EA Enhanced 8051 Core −3. MSC1210 Timing Compared to Standard 8051 Timing Flash Memory Family Device CompatibilityHigh Performance Analog Functions High-Performance Peripherals Description Program Memory Data Memory Internal RAM Description Program Memory −1. Program and Data Memory Size MSC1210Y2 MSC1210Y3 MSC1210Y4 MSC1210Y5 −2. Program and Data Memory Addresses Data MemoryOn-Chip Extended Static RAM Sram On-Chip Flash Data Memory External Data Memory Internal RAM −2. MSC1210 Memory Map Register Bank Stack Register Banks Bit Memory Or execute Special Function Register SFR Memory Defines the MSC1210 SFRs −1. SFR Names and Addresses SCON0 Referencing SFRs Referencing Bits of SFRs Bit−Addressable SFRs SFR Types SFR Definitions SFR Definitions SFR Definitions SFR Definitions Can be generated automatically by the MSC1210 P0DDRL/P0DDRH Port 0 Data Direction Low/High Byte, Addresses GCL/GCM/GCH Gain Low/Middle/High Byte, Addresses D4H/D5H/D6H SFR Definitions SFR Definitions SFR Definitions Describes the basic register functions of the MSC1210 ADC Accumulator Registers Register Program Counter PC Data Pointer DPTR0/DPTR1 Stack Pointer SP Describes the various addressing modes of the MSC1210 Immediate Addressing Mode Example−1. MSC1210 Addressing Modes Direct Addressing Indirect Addressing External Direct Addressing Movx A,@DPTR Movx @DPTR,A External Indirect Addressing Code Indirect Adressing Describes the program flow of the MSC1210 ADC Conditional Branching Direct Jumps Consider the example Returns From Routines Direct CallsInterrupts Description System Timers Startup Timing −1. Standard 8051 Timing System Timing System Timers −2. MSC1210 Timing Chain and Clock Control Microseconds Timer Milliseconds Timer −4. System Timing Interrupt Control One Hundred Millisecond Clock Flash Programming Mode Power-On Reset Timing Normal-Mode Power-On Reset TimingStartup Timing Symbol Parameter Min Max Unit Psen Describes the timers of the MSC1210 ADC Using Timers to Measure Time How Does a Timer Count?How Long Does a Timer Take to Count? Width Width ∝s RD or WR StrobeMovx Duration SYS CLKs At 12MHz −1. Timer Conrol SFRs Timer SFRsSFR Name Description SFR Address Bit Addressable? Tmod SFR Mode −2. Timer Modes and Usage TxM1 TxM0 Timer Description of Timer Mode Instruction −3. Example of 8-Bit Auto-ReloadCycle Tcon SFR Bit Name Bit Address Explanation of Function Timer−4. Tcon 88 H SFR Initializing a Timer Reading the Timer Detecting Timer Overflow Timing the Length of Events Using Timers as Event Counters Using Timer 1 T2CON SFR Timer 2 in Auto-Reload Mode Timer 2 in Capture Mode Timer 2 as a Baud Rate Generator Describes serial communication using the MSC1210 ADC Description Setting the Serial Port Mode Function Length Period −1. SM0 and SM1 Function Definitions Mode Serial Mode 0 Synchronous Half-Duplex High four bits bits 4 through 7 are configuration bits −2. Serial Port Mode 0 Receive Timing-High Speed Operation Serial Mode 1 Asynchronous Full-Duplex −3. Serial Port Mode 1 Transmit Timing BaudRate + Timer2Overflow −2. Common Baud Rates Using TimerBaudRate + 32 @ Timer1Overflow BaudRate + 12 @ 256 * TH1 Rcap 2H Rcap 2L + −3. Common Baud Rates Using TimerSerial Mode 2 Asynchronous Full-Duplex Baud Rate RCAP2HRCAP2L @ 11.0592MHz f OSC −6. Serial Port 0 Mode 2 Receive Timing BaudRate + 2SMOD @ fOSC Serial Mode 3 Asynchronous Full-Duplex −7. Serial Port 0 Mode 3 Transmit Timing Setting the Serial Port Mode TH1 = 256 − Crystal / 192 / Baud Setting the Serial Port Baud Rate−4. Mode 0 Commonly Used Baud Rates Baud Rate −5. Baud Rate Settings for Timer Desired Baud Writing to the Serial Port −6. Baud Rate Settings for TimerBaud Rate 33MHz clk 25MHz clk 11.0592MHz clk Kb/s Reading the Serial Port Describes the interrupts of the MSC1210 ADC JNB TF0,SKIPTOGGLE Events That Can Trigger Interrupts Interrupt/Event Addr Priority Flag Enable Priority Control−1.Interrupt Sources 10-4 −3.EICON D8 H SFR Enabling Interrupts−2.IE A8 H SFR −4.EIE E8 H SFR Polling Sequence −5.IP B8 H SFR Interrupt Priorities−6.EIP F8 H SFR Interrupt Triggering Exiting Interrupts Serial Interrupts Types of InterruptsExternal Interrupts −7.EXIF 91 H SFR Bit Name Explanation of Function Watchdog Interrupt Timer InterruptsAuxiliary Interrupts −9.AIE A6 H SFR −8.Clearing Auxiliary InterruptsAux Interrupt Type Method to Clear Interrupt −11. PAI A5 H SFR −10. Aistat A7 H SFRBit Name Explanation of Function Clear Interrupt −12. PPI Bits of PAI SFR PAIx Bits Explanation of Interrupt/Event Waking Up from Idle Mode −13. EWU C6 H SFR Register Protection Push PSW Push R0 Error − Invalid instruction Common Problems with Interrupts Tone Generator 11-3 Description 11-2PWM Generator 11-5 −1. Block Diagram Tone Generator ToneFrequency +1 −3. Timing Diagram of Tone Generator in Staircase Mode Tone Generator Waveforms Duty Cycle = PWM Period +1 − PWM Duty/PWM Period +1 PWM Generator−1. PWM Polarity Conditions Condition Duty Cycle −5. Timing Diagram of a PWM Waveform This can be expressed in code as Example of PWM Tone Generation −2. Configuring the PWM for Tone GenerationStmt ‘C’ Source Code Assembly Source Code −3. Statement Explanations Example of PWM Tone Generation Idling −5. Statement Explanations −4. Configuring the PWM for Tone Generation with PWM IdlingExplanation Example of Updating PWM −6. PWM Timing 11-12 PGA DAC 12-10 −1. MSC1210 Architecture −2. Input Multiplexer Configuration Input Multiplexer Positive Input Negative Input Temperature Sensor 12-6 Burnout Current Sources MSB @ 10 Input BufferAnalog Input ACLKFrequency −1.PGA Settings Programmable Gain Amplifier PGA Offset DAC Modulator Calibration Mode −2.Calibration Mode Control BitsCalibration Digital Filter −4. Filter Step Responses −5. Filter Frequency Responses −4.Output Data Rate and Channel Rate Multiplexing Channels−3.Filter Settling Samples to Discard Filter Voltage Reference −5.Output Data Rate and Channel Rate 10x faster Summation/Shifter Register Source Summation Count Shift Summation Count Manual Summation Mode ADC Summation Mode Manual Shift Divide Mode ADC Summation with Shift Divide Mode Interrupt-Driven ADC Sampling Analog-to-Digital Converter 12-21 Syncronizing Multiple MSC1210 Devices Analog-to-Digital Converter 12-23 PT100 Ratiometric MeasurementsADC Result + V REF ADC Result + R REF @ I OUT Differential Vref 12-26 SPI System Errors 13-6 Clock Phase and Polarity Controls 13-4SPI Signals 13-5 Description 13-2 −1. SPI block diagram Functional Description −2. SPI Clock/Data Timing Clock Phase and Polarity Controls Master Out Slave SPI SignalsMaster In Slave Out Serial Clock SPI System Errors −3. SPI Reset State Data Transfers 13-8 Fifo Operation −4. SPI Fifo Operation Code Examples SPI Master Transfer in Fifo Mode using Interrupts 13-12 Description 14-2 Watchdog Timer 14-4Low-Voltage Detect 14-2 −1. Brownout Reset and Low-Voltage Detection Low-Voltage Detect −1.Typical Sub-Circuit Current Consumption Power Supply−2.Comparator Specification −3.Band Gap Parameters Watchdog Timer Watchdog Timer Hardware Configuration Enabling Watchdog Timer Watchdog Timer Resetting the Watchdog Timer Disabling Watchdog Timer Watchdog Timeout/Activation Advanced Flash Memory 15-6 Hardware Configuration 15-2Power Optimization 15-9 Breakpoint Generator 15-7 Hardware Configuration Hardware Configuration Registers Hardware Configuration Register 0 HCR0 DFSEL2/1/0 Amount of Flash Data Memory Hardware Configuration Register 1 HCR1 Hardware Configuration Memory Accessing Configuration Memory in a User Program Advanced Flash Memory Updating Interrupts with Reset Sector LockWrite Protecting Flash Program Memory Configuring Breakpoints Breakpoint Generator Breakpoint Auxiliary Interrupt Disabling a Breakpoint Power Optimization Flash Memory as Data Memory Advanced Topics 15-11 Advanced Topics and Other Information Describes the 8052 Assembly Language Syntax Label and instruction Number Bases Expressions −1.Order of Precedence for Mathematical Operators Operator PrecedenceCharacters and Character Strings Order Operator Changing Program Flow LJMP, SJMP, Ajmp Ljmp LABEL3 Subroutines LCALL, ACALL, RET Register Assignment MOV MOV DestinationRegister,SourceValue MOV R2,R1 Invalid MOV @R0,A Incrementing and Decrementing Registers INC, DEC Program Loops Djnz Setting, Clearing, and Moving Bits SETB, CLR, CPL, MOV 16-14 Bit-Based Decisions and Branching JB, JBC, JNB, JC, JNC Value Comparison Cjne Lcall Debouncekey Less Than and Greater Than Comparison Cjne Checkless JC Aisless Zero and Non-Zero Decisions JZ/JNZ Performing Additions ADD, Addc Performing Additions ADD, Addc Performing Subtractions Subb Performing Multiplication MUL Performing Division DIV Shifting Bits RR, RRC, RL, RLC −1. Rotate Operations −3.Results of ORL Bit-Wise Logical Instructions ANL, ORL, XRL−2.Results of ANL −4.Results of XRL Assembly Language 16-25 Exchanging Register Values XCH Swapping Accumulator Nibbles Swap Adjusting Accumulator for BCD Addition DA Using the Stack PUSH/POP Assembly Language 16-29 Setting the Data Pointer Dptr MOV Dptr Reading and Writing External RAM/Data Memory Movx Reading Code Memory/Tables Movc Lcall SUB SUB INC a Using Jump Tables JMP @A+DPTR Describes the Keil simulator and its functions 17-2 Keil Simulator 17-3 Timers −1. Timer/Counter 0 − Mode Timer 0 & 1 Example −2. Timer/Counter −4. Timer/Counter 1 Mode Keil Simulator 17-7 17-8 Keil Simulator 17-9 17-10 −1.Timer/Counter 2 Control Bits TimerRegister Bit Toggle Box Name −7. Status of Watchdog Peripheral Watchdog Reset Facility Example 17-14 Keil Simulator 17-15 System Timer Clock Control Analog-to-Digital Converter −8. Analog−to−Digital Converter Peripheral −9. Error Message Summation/Shifter −10. Accumulator/Shifter Peripheral 17.8.1 ADC/Summation/Shifter Example 17-22 Keil Simulator 17-23 17-24 Keil Simulator 17-25 17-26 Keil Simulator 17-27 −11. summation/Shifter Peripheral Keil Simulator 17-29 −13. List Box for the Interrupt Peripheral −14. Parallel Port 0 Contents Display Window Ports Serial Peripheral Interface SPI −16. SPI Peripheral Window Keil Simulator 17-33 SPI Sample Code Keil Simulator 17-35 Serial Peripheral Interface SPI Keil Simulator 17-37 17.12 ∝Vision 2 Debug Program Example −17. Keil Debugger Serial Port I/O −18. Serial Channel 0 Communication Peripheral 17-42 BaudRate + fOSC Transmit Block Baud Rate ComputationBaudRate + fOSC @ Receive Block Baud Rate Computation −19. Clock Control Peripheral Additional Resource Appendix a Topic Additional Features in the MSC1210 Compared to Appendix B MSC1210 Timing Chain and Clock Control Diagram Figure B−1. MSC1210 Timing Chain and Clock Control Appendix C Table C−1. Boot ROM Routines Address Routine Declarations Description Boot ROM Routines Page Appendix D 8052 Instruction-Set Quick-Reference Guide JB bitAddr,relAddr Ajmp pg1Addr Appendix E Description Instruction Set Description Absolute Call within 2k Block 8052 Instruction SetAcall Acall codeAddress Add Value, Add Value with Carry ADD, AddcADD A,operand Absolute Jump within 2k Block AjmpAjmp codeAddress Bitwise ANLANL operand1,operand2 Clear Register Compare and Jump if Not EqualCLR Cjne operand1,operand2,reladdr Complement Register Decimal Adjust AccumulatorCPL CPL operand DEC register Decrementing the value causes it to reset to 255 0xFFHCarry flag is not set when the value rolls over from 0 to See also INC, Subb Decrement and Jump if Not Zero Djnz register,relAddr Increment Reister INCINC register Jump if Bit Set and Clear Bit Jump if Bit SetJBC Jump if Carry Set JNB JMPJNC Lcall JNZLjmp Not affected See also MOVC, MOVX, XCH, XCHD, PUSH, POP MOV operand1, operand2MOV bit1,bit2 Move into/out of Internal RAM MOVMOV operand1,operand2 Movc MOV DptrMovx NOP MULMultiply Accumulator by B No Operation Bitwise or ORLSyntax ORL operand1,operand2 Push POPPop Value from Stack Push Value onto Stack Reti RETReturn from Subroutine Return from Interrupt RRC RLCSetb Subb SjmpShort Jump Subtract from Accumulator with Borrow XCH SwapXchd XRL Bitwise Exclusive or Undefined Instructions OpCode Bytes Cycles Flags ??? 0xA5 Appendix F EX2-External 2 Interrupt Enable Enable Interrupt Control EiconExtended Interrupt Enable EIE Bit Addressable SFRs alphabetical Interrupt Enable IE Extended Interrupt Priority EIP Interrupt Priority IP Port 0 P0 Port 1 P1 Port 2 P2 Port 3 P3 Program Status Word PSW Register Bank Register Bank Addresses Serial Mode Description Baud Serial Control Scon Timer Control Tcon Tcon Timer 2 Control T2CON T2CON Appendix G SFR/Address Cross-Reference SFR Name Description SFR Address Hex SFRs/Address Cross-Reference Guide alphabetical Spircon