Writing to the Serial Port | Texas Instruments MSC1210 manual

Writing to the Serial Port

Table 9−6. Baud Rate Settings for Timer 2.

Baud Rate				33MHz clk		25MHz clk		11.0592MHz clk
Baud Rate
(kb/s)	C/T2			RCAP2H	RCAP2L	RCAP2H	RCAP2L	RCAP2H	RCAP2L
19.2	0			FFH	EEH	FFH	F2H	FFH	FAH
9.6	0			FFH	CAH	FFH	D7H	FFH	EEH
4.8	0			FFH	95H	FFH	AFH	FFH	DCH
2.4	0			FFH	29H	FFH	5DH	FFH	B8H
1.2	0			FEH	52H	FEH	BBH	FFH	70H
1.2	0			FCH	A5H	FDH	75H	FEH	E0H

9.4 Writing to the Serial Port

Once the serial port has been properly configured as explained previously, the serial port is ready to be used to send and receive data. If you think configuring the serial port was easy, using the serial port will be even easier.

To write a byte to the serial port, simply write the value to the SBUF0 (99H) SFR. For example, sending the letter A to the serial port is accomplished as easily as:

MOV SBUF0,#’A’

Upon execution of the above instruction, the MSC1210 will begin transmitting the character via the serial port. Obviously, transmission is not instanta- neous—it takes a measurable amount of time to transmit the eight data bits that make up the byte, along with its start and stop bits—and because the MSC1210 does not have a serial output buffer, you need to be sure that a char- acter is completely transmitted before trying to transmit the next character.

The MSC1210 lets you know when it is done transmitting a character by setting the TI bit in SCON. When this bit is set, the last character has been transmitted and the next character, if any, may be sent. Consider the following code segment:

CLR TI		;Be sure the	bit is		initially clear
MOV	SBUF,#’A’	;Send the letter		‘A’ to		the serial port
JNB	TI,$	;Pause until	the	RI	bit	is set.

The above three instructions transmit a character and wait for the TI bit to be set before continuing. The last instruction says jump if the TI bit is not set to $. The $ character (in most assemblers), means the same address of the cur- rent instruction. Therefore, the MSC1210 will pause on the JNB instruction un- til the TI bit is set (upon successful transmission of the character).

Serial Communication	9-15

Image 105

Texas Instruments MSC1210 manual Writing to the Serial Port, 6. Baud Rate Settings for Timer

Contents

User’s Guide Important Notice Introduction to the MSC1210 MSC1210 Memory OrganizationBasic Registers Addressing Modes System TimingSerial Communication Analog-to-Digital Converter Pulse Width Modulator/Tone Generator Additional MSC1210 Hardware Serial Peripheral Interface SPI Additional Resource Clock Timing Diagram Additional Features in the MSC1210 Compared toBoot ROM Routines Instruction-Set Quick-Reference Guide SPI/PWM/Flash Write Timing System Timing Interrupt Control 16−1 Pin Descriptions of the MSC1210 14−2 Chapter MSC1210 Description −1. MSC1210 Block Diagram MSC1210 Pin-Out −2. Pin Configuration of the MSC1210 Pin # Name Description −1. Pin Descriptions of the MSC1210 Pin # Name Description −1 Pin Descriptions of the MSC1210 AD7 1 I/O Ports P0, P1, P2, and P3 Port Port Oscillator Inputs XTAL1 and XTAL2 Reset Line RST Address Latch Enable ALEProgram Store Enable Psen External Access EA −3. MSC1210 Timing Compared to Standard 8051 Timing Enhanced 8051 Core Family Device Compatibility Flash MemoryHigh Performance Analog Functions High-Performance Peripherals Description Program Memory Data Memory Internal RAM Program Memory Description MSC1210Y2 MSC1210Y3 MSC1210Y4 MSC1210Y5 −1. Program and Data Memory Size Data Memory −2. Program and Data Memory AddressesOn-Chip Extended Static RAM Sram External Data Memory On-Chip Flash Data Memory −2. MSC1210 Memory Map Register Bank Internal RAM Register Banks Stack Bit Memory Or execute Special Function Register SFR Memory Defines the MSC1210 SFRs SCON0 −1. SFR Names and Addresses Referencing Bits of SFRs Referencing SFRs SFR Types Bit−Addressable SFRs 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 Registers Accumulator Program Counter PC Register Stack Pointer SP Data Pointer DPTR0/DPTR1 Describes the various addressing modes of the MSC1210 Mode Example Immediate Addressing−1. MSC1210 Addressing Modes Direct Addressing Indirect Addressing Movx A,@DPTR Movx @DPTR,A External Direct Addressing Code Indirect Adressing External Indirect Addressing Describes the program flow of the MSC1210 ADC Direct Jumps Conditional Branching Consider the example Direct Calls Returns From RoutinesInterrupts Description System Timers Startup Timing −1. Standard 8051 Timing System Timing System Timers −2. MSC1210 Timing Chain and Clock Control Milliseconds Timer Microseconds Timer −4. System Timing Interrupt Control One Hundred Millisecond Clock Normal-Mode Power-On Reset Timing Flash Programming Mode Power-On Reset TimingStartup Timing Psen Symbol Parameter Min Max Unit Describes the timers of the MSC1210 ADC How Does a Timer Count? Using Timers to Measure TimeHow Long Does a Timer Take to Count? RD or WR Strobe Width Width ∝sMovx Duration SYS CLKs At 12MHz Timer SFRs −1. Timer Conrol SFRsSFR Name Description SFR Address Bit Addressable? Mode Tmod SFR TxM1 TxM0 Timer Description of Timer Mode −2. Timer Modes and Usage −3. Example of 8-Bit Auto-Reload InstructionCycle Bit Name Bit Address Explanation of Function Timer Tcon SFR−4. Tcon 88 H SFR Reading the Timer Initializing a Timer Detecting Timer Overflow Timing the Length of Events Using Timers as Event Counters 1 T2CON SFR Using Timer 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 Function Length Period Setting the Serial Port Mode Mode −1. SM0 and SM1 Function Definitions High four bits bits 4 through 7 are configuration bits Serial Mode 0 Synchronous Half-Duplex Serial Mode 1 Asynchronous Full-Duplex −2. Serial Port Mode 0 Receive Timing-High Speed Operation −3. Serial Port Mode 1 Transmit Timing BaudRate + 32 @ Timer1Overflow −2. Common Baud Rates Using TimerBaudRate + Timer2Overflow BaudRate + 12 @ 256 * TH1 Serial Mode 2 Asynchronous Full-Duplex −3. Common Baud Rates Using TimerRcap 2H Rcap 2L + Baud Rate RCAP2HRCAP2L @ 11.0592MHz f OSC BaudRate + 2SMOD @ fOSC −6. Serial Port 0 Mode 2 Receive Timing −7. Serial Port 0 Mode 3 Transmit Timing Serial Mode 3 Asynchronous Full-Duplex Setting the Serial Port Mode −4. Mode 0 Commonly Used Baud Rates Setting the Serial Port Baud RateTH1 = 256 − Crystal / 192 / Baud Baud Rate Desired Baud −5. Baud Rate Settings for Timer −6. Baud Rate Settings for Timer Writing to the Serial PortBaud Rate 33MHz clk 25MHz clk 11.0592MHz clk Kb/s Reading the Serial Port Describes the interrupts of the MSC1210 ADC JNB TF0,SKIPTOGGLE Interrupt/Event Addr Priority Flag Enable Priority Control Events That Can Trigger Interrupts−1.Interrupt Sources 10-4 −2.IE A8 H SFR Enabling Interrupts−3.EICON D8 H SFR −4.EIE E8 H SFR Polling Sequence Interrupt Priorities −5.IP B8 H SFR−6.EIP F8 H SFR Exiting Interrupts Interrupt Triggering Types of Interrupts Serial InterruptsExternal Interrupts Bit Name Explanation of Function −7.EXIF 91 H SFR Timer Interrupts Watchdog InterruptAuxiliary Interrupts −8.Clearing Auxiliary Interrupts −9.AIE A6 H SFRAux Interrupt Type Method to Clear Interrupt −10. Aistat A7 H SFR −11. PAI A5 H SFRBit Name Explanation of Function Clear Interrupt PAIx Bits Explanation of Interrupt/Event −12. PPI Bits of PAI SFR −13. EWU C6 H SFR Waking Up from Idle Mode Push PSW Register Protection Push R0 Error − Invalid instruction Common Problems with Interrupts Description 11-2 Tone Generator 11-3PWM Generator 11-5 −1. Block Diagram ToneFrequency +1 Tone Generator Tone Generator Waveforms −3. Timing Diagram of Tone Generator in Staircase Mode −1. PWM Polarity Conditions PWM GeneratorDuty Cycle = PWM Period +1 − PWM Duty/PWM Period +1 Condition Duty Cycle −5. Timing Diagram of a PWM Waveform This can be expressed in code as Stmt ‘C’ Source Code Assembly Source Code −2. Configuring the PWM for Tone GenerationExample of PWM Tone Generation −3. Statement Explanations Example of PWM Tone Generation Idling −4. Configuring the PWM for Tone Generation with PWM Idling −5. Statement ExplanationsExplanation −6. PWM Timing Example of Updating PWM 11-12 12-10 PGA DAC −1. MSC1210 Architecture Input Multiplexer −2. Input Multiplexer Configuration Negative Input Positive Input Temperature Sensor 12-6 MSB Burnout Current Sources Analog Input Input Buffer@ 10 ACLKFrequency Programmable Gain Amplifier PGA −1.PGA Settings Modulator Offset DAC −2.Calibration Mode Control Bits Calibration ModeCalibration −4. Filter Step Responses Digital Filter −5. Filter Frequency Responses −3.Filter Settling Multiplexing Channels−4.Output Data Rate and Channel Rate Samples to Discard Filter −5.Output Data Rate and Channel Rate 10x faster Voltage Reference Source Summation/Shifter Register Shift Summation Count Summation Count ADC Summation Mode Manual Summation Mode ADC Summation with Shift Divide Mode Manual Shift Divide Mode Interrupt-Driven ADC Sampling Analog-to-Digital Converter 12-21 Syncronizing Multiple MSC1210 Devices Analog-to-Digital Converter 12-23 ADC Result + V REF Ratiometric MeasurementsPT100 ADC Result + R REF @ I OUT Differential Vref 12-26 SPI Signals 13-5 Clock Phase and Polarity Controls 13-4SPI System Errors 13-6 Description 13-2 Functional Description −1. SPI block diagram −2. SPI Clock/Data Timing Clock Phase and Polarity Controls Master In Slave Out SPI SignalsMaster Out Slave Serial Clock SPI System Errors Data Transfers −3. SPI Reset State 13-8 −4. SPI Fifo Operation Fifo Operation Code Examples SPI Master Transfer in Fifo Mode using Interrupts 13-12 Watchdog Timer 14-4 Description 14-2Low-Voltage Detect 14-2 Low-Voltage Detect −1. Brownout Reset and Low-Voltage Detection −2.Comparator Specification Power Supply−1.Typical Sub-Circuit Current Consumption −3.Band Gap Parameters Watchdog Timer Hardware Configuration Watchdog Timer Enabling Watchdog Timer Watchdog Timer Resetting the Watchdog Timer Watchdog Timeout/Activation Disabling Watchdog Timer Power Optimization 15-9 Hardware Configuration 15-2Advanced Flash Memory 15-6 Breakpoint Generator 15-7 Hardware Configuration Registers Hardware Configuration DFSEL2/1/0 Amount of Flash Data Memory Hardware Configuration Register 0 HCR0 Hardware Configuration Register 1 HCR1 Accessing Configuration Memory in a User Program Hardware Configuration Memory Updating Interrupts with Reset Sector Lock Advanced Flash MemoryWrite Protecting Flash Program Memory Breakpoint Generator Configuring Breakpoints Disabling a Breakpoint Breakpoint Auxiliary Interrupt 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 Expressions Number Bases Characters and Character Strings Operator Precedence−1.Order of Precedence for Mathematical Operators Order Operator Ljmp LABEL3 Changing Program Flow LJMP, SJMP, Ajmp Subroutines LCALL, ACALL, RET MOV DestinationRegister,SourceValue Register Assignment MOV 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 Lcall Debouncekey Value Comparison Cjne Checkless JC Aisless Less Than and Greater Than Comparison Cjne Performing Additions ADD, Addc Zero and Non-Zero Decisions JZ/JNZ Performing Additions ADD, Addc Performing Subtractions Subb Performing Multiplication MUL Performing Division DIV −1. Rotate Operations Shifting Bits RR, RRC, RL, RLC −2.Results of ANL Bit-Wise Logical Instructions ANL, ORL, XRL−3.Results of ORL −4.Results of XRL Assembly Language 16-25 Swapping Accumulator Nibbles Swap Exchanging Register Values XCH 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 Lcall SUB Reading Code Memory/Tables Movc SUB INC a Using Jump Tables JMP @A+DPTR Describes the Keil simulator and its functions 17-2 Keil Simulator 17-3 −1. Timer/Counter 0 − Mode Timers −2. Timer/Counter Timer 0 & 1 Example −4. Timer/Counter 1 Mode Keil Simulator 17-7 17-8 Keil Simulator 17-9 17-10 Timer −1.Timer/Counter 2 Control BitsRegister Bit Toggle Box Name −7. Status of Watchdog Peripheral Watchdog Reset Facility Example 17-14 Keil Simulator 17-15 Clock Control System Timer Analog-to-Digital Converter −8. Analog−to−Digital Converter Peripheral −9. Error Message −10. Accumulator/Shifter Peripheral Summation/Shifter 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 Ports −14. Parallel Port 0 Contents Display Window −16. SPI Peripheral Window Serial Peripheral Interface SPI 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 Transmit Block Baud Rate Computation BaudRate + fOSCBaudRate + fOSC @ Receive Block Baud Rate Computation −19. Clock Control Peripheral Additional Resource Topic Appendix a Additional Features in the MSC1210 Compared to Appendix B Figure B−1. MSC1210 Timing Chain and Clock Control MSC1210 Timing Chain and Clock Control Diagram Appendix C Address Routine Declarations Description Table C−1. Boot ROM Routines Boot ROM Routines Page Appendix D JB bitAddr,relAddr Ajmp pg1Addr 8052 Instruction-Set Quick-Reference Guide Description Instruction Set Appendix E Description Acall 8052 Instruction SetAbsolute Call within 2k Block Acall codeAddress ADD, Addc Add Value, Add Value with CarryADD A,operand Ajmp Absolute Jump within 2k BlockAjmp codeAddress ANL BitwiseANL operand1,operand2 CLR Compare and Jump if Not EqualClear Register Cjne operand1,operand2,reladdr CPL Decimal Adjust AccumulatorComplement Register CPL operand Carry flag is not set when the value rolls over from 0 to Decrementing the value causes it to reset to 255 0xFFHDEC register See also INC, Subb Djnz register,relAddr Decrement and Jump if Not Zero INC Increment ReisterINC register JBC Jump if Bit SetJump if Bit Set and Clear Bit Jump if Carry Set JMP JNBJNC JNZ LcallLjmp MOV operand1, operand2 Not affected See also MOVC, MOVX, XCH, XCHD, PUSH, POPMOV bit1,bit2 MOV Move into/out of Internal RAMMOV operand1,operand2 MOV Dptr MovcMovx Multiply Accumulator by B MULNOP No Operation ORL Bitwise orSyntax ORL operand1,operand2 Pop Value from Stack POPPush Push Value onto Stack Return from Subroutine RETReti Return from Interrupt RLC RRCSetb Short Jump SjmpSubb Subtract from Accumulator with Borrow Swap XCHXchd Bitwise Exclusive or XRL Instructions OpCode Bytes Cycles Flags ??? 0xA5 Undefined Appendix F Extended Interrupt Enable EIE Enable Interrupt Control EiconEX2-External 2 Interrupt Enable Bit Addressable SFRs alphabetical Extended Interrupt Priority EIP Interrupt Enable IE Port 0 P0 Interrupt Priority IP Port 2 P2 Port 1 P1 Port 3 P3 Register Bank Register Bank Addresses Program Status Word PSW Serial Control Scon Serial Mode Description Baud Tcon Timer Control Tcon T2CON Timer 2 Control T2CON Appendix G SFR Name Description SFR Address Hex SFR/Address Cross-Reference SFRs/Address Cross-Reference Guide alphabetical Spircon