Cmsemicon CMS32L051 - Calculation of the Baud Rate

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V1.2.2

CMS32L051 User Manual |Chapter 12 Universal Serial Communication Unit

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12.7.3 Calculation of the baud rate

(1) Formula for calculating the baud rate

The baud rate of UART (UART0~UART2) communication can be calculated using the following

formula:

Note The SDRmn [15:9] of the serial data register mn (SDRmn) is disabled from being set to 0000000B and

0000001B.

Notice 1 Because the value of SDRmn [15:9] when using UART is the value of bit15~9 of the SDRmn register (0000010B

~1111111B), so 2~127.

2.m: Unit number (m=0, 1) n: channel number (n=0~2). mn=00~03, 10~11.

The operating clock (f

MCK

) depends on the serial clock select register m (SPSm) and bit 15 (CKSmn

bit) of the serial mode register mn (SMRmn).

(baud rate) = {Clock of the object channel (f

MCK

) frequency}× (SDRmn[15:9]+ 1)

2[bps]

Main Page

default chapter2
- Documentation Instructions2
- Table of Contents3
Chapter 1 CPU14
- 1.1 Overview14
- 1.2 Cortex-M0+ Core Features14
- 1.3 Debugging Features14
- 1.4 SWD Interface Pin16
- 1.5 ARM Reference Document17
Chapter 2 Pin Function18
- 2.1 Port Function18
- 2.2 Port Multiplexing Function18
- 2.3 Registers for Controlling Port Functions19
- Port Mode Register (Pmxx)21
- Port Register (Pxx)22
- Port Set Control Register (Psetxx)23
- Port Clear Control Register (Pclrxx)24
- Pull-Up Resistor Selection Register (Puxx)25
- Pull-Down Resistor Selection Register (Pdxx)26
- Port Output Mode Register (Pomxx)27
- Port Mode Control Register (Pmcxx)28
- Port Output Multiplexing Function Configuration Register (Pxxcfg)29
- Port Input Multiplexing Function Configuration Registers33
- Ti13Pcfg, Intp0Pcfg, Intp1Pcfg , Intp2Pcfg, Intp3Pcfg, Sdi00Pcfg, Sclki00Pcfg, Ss00Pcfg , Sdi20Pcfg, Sclki20Pcfg, Sdaa0Pcfg, Scla0Pcfg, Rxd1Pcfg )33
- SPI Port Multiplexing Configuration Register (SPIPCFG)37
- 2.4 Handling of Unused Pins38
- Register Setting When Using the Multiplexed Function39
- Basic Idea When Using the Multiplexed Output Feature39
- Example of Register Settings Using Port Functions and Multiplexing Functions40
- EPWM Port Configuration Method56
Chapter 3 System Structure57
- 3.1 Overview57
- 3.2 System Address Partition58
Chapter 4 Clock Generation Circuit60
- 4.1 Function of the Clock Generation Circuit60
- 4.2 Structure of Clock Generation Circuit62
- 4.3 Registers for Controlling Clock Generation Circuit65
- Clock Operation Mode Control Register (CMC)65
- System Clock Control Register (CKC)67
- Clock Operation Status Control Register (CSC)68
- Status Register of the Oscillation Stabilization Time Counter (OSTC)69
- Oscillation Stabilization Time Selection Register (OSTS)71
- Peripheral Enable Registers 0, 1 (PER0, PER1)72
- Subsystem Clock Supply Mode Control Register (OSMC)76
- High-Speed Internal Oscillator Frequency Selection Register (HOCODIV)77
- High-Speed Internal Oscillator Trim Register (HIOTRM)78
- Subsystem Clock Selection Register (SUBCKSEL)79
- 4.4 System Clock Oscillation Circuit80
- X1 Oscillation Circuit80
- XT1 Oscillation Circuit80
- High-Speed Internal Oscillator84
- Low-Speed Internal Oscillator84
- 4.5 Operation of Clock Generation Circuit85
- Clock Control87
- Example of Setting up a High-Speed Internal Oscillator87
- Example of Setting up an X1 Oscillation Circuit89
- Example of Setting up an XT1 Oscillation Circuit90
- State Transition Graph of the CPU Clock91
- Conditions before CPU Clock Transfer and Processing after Transfer97
- Time Required to Switch between CPU Clock and Main System Clock99
- Condition before the Clock Oscillation Stops100
- 4.7 High-Speed Internal Oscillation Correction101
- High-Speed Internal Oscillation Self-Adjustment Function101
- Register Description102
- Operation Description103
- Precautions for Use106
Chapter 5 Universal Timer Unit (Timer4)107
- 5.1 Function of Universal Timer Unit108
- Independent Channel Operation Function108
- Multi-Channel Linkage Operation Function110
- 8-Bit Timer Operation Function (Limited to Channel 1 and Channel 3 of Unit 0)111
- LIN-Bus Support Functions (Channel 3 of Unit 0 Only)111
- 5.2 Structure of the Universal Timer Unit112
- List of Universal Timer Unit 0 Registers115
- List of Universal Timer Unit 1 Registers116
- Timer Count Register Mn (Tcrmn)117
- Timer Data Register Mn (Tdrmn)118
- 5.3 Registers for Controlling General-Purpose Timer Unit119
- Peripheral Enable Register 0 (PER0)120
- Timer Clock Select Register M (Tpsm)121
- Timer Mode Register Mn (Tmrmn)124
- Timer Status Register Mn (Tsrmn)129
- Timer Channel Enable Status Register M (Tem)130
- Timer Channel Start Register M (Tsm)131
- Timer Channel Stop Register M (Ttm)132
- Timer Input-Output Select Register (TIOS0)133
- Timer Output Enable Register M (Toem)134
- Timer Output Register M (Tom)135
- Timer Output Level Register M (Tolm)136
- Timer Output Mode Register M (Tomm)137
- Noise Filter Enable Register 1 (NFEN1)138
- Noise Filter Enable Register 2 (NFEN2)139
- Registers for Controlling Timer Input/Output Pin Port Functions140
- 5.4 Basic Rules of the Universal Timer Unit141
- Basic Rules of the Multi-Channel Linkage Operation Function141
- Basic Rules for the 8-Bit Timer to Operate the Function143
- 5.5 Operation of the Counter144
- Count Clock (F TCLK )144
- Start Timing of Counter146
- Operation of Counter147
- Control of the Channel Output (Tomn Pin)152
- Structure of the Tomn Pin Output Circuit152
- Output Setting of the Tomn Pin153
- Cautions for Channel Output Operation154
- One-Time Operation of the Tomn Bit158
- Timer Interrupt and Tomn Pin Output When Counting Starts159
- Control of Timer Input (Timn)160
- Structure of Timn Pin Input Circuit160
- Noise Filter161
- Considerations When Manipulating Channel Inputs162
- 5.8 Independent Channel Operation Function of the Universal Timer Unit163
- Operates as an Interval Timer / Square Wave Output163
- Operate as External Event Counter167
- Operates as Frequency Divider170
- Operates as Input Pulse Interval Measurement173
- Operation as Input Signal High and Low Level Width Measurement176
- Operation as Delay Counter180
- 5.9 Multi-Channel Linkage Operation of the Universal Timer Unit183
- Operates as Single-Trigger Pulse Output Function183
- Operates as PWM Function190
- Operates as Multiplex PWM Output Function197
Chapter 6 Function of EPWM Output Control Circuit205
- 6.1 Structure of the Output Control Circuit205
- 6.2 Registers for Controlling EPWM Output Control Circuit206
- Peripheral Enable Register 1 (PER1)207
- EPWM Input Source Selection Register (EPWMSRC)207
- EPWM Output Control Register (EPWMCTL)207
- EPWM Force Truncated Input Selection Register (EPWMSTC)208
- EPWM Force Truncated Output Selection Register (EPWMSTL)209
- EPWM Status Register (EPWMSTR)209
- 6.3 Operation of EPWM Output Control Circuit211
- Initial Setup211
- Normal Operation212
- Force Truncation Processing212
- 6.4 Control Example of Brushless DC Motor214
- Example of a Hardware Connection214
- Control Timing of Three-Phase Brushless DC Motors215
- Example of Register Setting216
- 6.5 Example of Stepper Motor Control217
- Example of a Hardware Connection217
- Control Method218
- Example of Register Setting219
Chapter 7 Real-Time Clock220
- 7.1 Function of Real-Time Clock220
- 7.2 Structure of Real-Time Clock220
- 7.3 Registers for Controlling Real-Time Clock222
- Peripheral Enable Register 0 (PER0)223
- Real-Time Clock Selection Register (RTCCL)224
- Real-Time Clock Control Register0 (RTCC0)225
- Real-Time Clock Control Register1 (RTCC1)226
- Clock Error Correction Register (SUBCUD)228
- Second Count Register (SEC)229
- Minute Count Register (MIN)229
- Hour Count Register (HOUR)230
- Day Count Register (DAY)232
- Week Count Register (WEEK)233
- Month Count Register (MONTH)234
- Year Count Register (YEAR)234
- Alarm Minute Register (ALARMWM)235
- Alarm Hour Register (ALARMWH)235
- Alarm Week Register (ALARMWW)236
- Port Mode Register and Port Register236
- Operation of Real-Time Clock237
- Start of Real-Time Clock Operation237
- Shifting to Sleep Mode after Starting Operation238
- Read and Write to the Real-Time Clock Counter239
- Alarm Setting for Real-Time Clock241
- 1Hz Output of the Real-Time Clock242
- Example of Clock Error Correction for a Real-Time Clock243
Chapter 8 15-Bit Interval Timer245
- 8.1 Function of 15-Bit Interval Timer245
- 8.2 Structure of 15-Bit Interval Timer245
- 8.3 Registers for Controlling 15-Bit Interval Timer246
- Peripheral Enable Register 0 (PER0)246
- Real-Time Clock Selection Register (RTCCL)247
- 15-Bit Interval Timer Control Register (ITMC)248
- 8.4 15-Bit Interval Timer Operation249
- 15-Bit Interval Timer Operation Timing249
- Start of Count Operation and Re-Enter to Sleep Mode after Returned from Sleep Mode250
Chapter 9 Clock Output/Buzzer Output Controller251
- 9.1 Functions of Clock Output/Buzzer Output Controller251
- 9.2 Structure of Clock Output/Buzzer Output Controller253
- 9.3 Registers for Controlling Clock Output/Buzzer Output Controller253
- Clock Output Select Register N (Cksn)253
- 9.4 Operation of Clock Output/Buzzer Controller256
- Operation of Output Pin256
- 9.5 Cautions for Clock Output/Buzzer Output Control Circuitry256
Chapter 10 Watchdog Timer257
- Function of Watchdog Timer257
- Structure of Watchdog Timer257
- Registers for Controlling Watchdog Timer259
- Watchdog Timer Enable Register (WDTE)259
- LOCKUP Control Register (Lockctl)And Its Protection Register (PRCR)260
- Operation of the Watchdog Timer261
- Operational Control of the Watchdog Timer261
- Watchdog Timer Overflow Time Setting262
- Setting Window Open Period of Watchdog Timer263
- Setting Watchdog Timer Interval Interruption264
- Operation of the Watchdog Timer During LOCKUP264
- A/D Converter265
- Function of A/D Converter265
- Control Registers of A/D Converter267
- Peripheral Enable Register 0 (PER0)268
- A/D Converter Mode Register 0 (ADM0)269
- A/D Converter Mode Register 1 (ADM1)274
- A/D Converter Mode Register 2 (ADM2)275
- A/D Converter Trigger Mode Register (ADTRG)276
- Analog Input Channel Specification Register (ADS)277
- 12-Bit A/D Conversion Result Register (ADCR)279
- 8-Bit A/D Conversion Result Register (ADCRI)280
- Conversion Result Comparison Upper Limit Setting Register (ADUL)280
- Conversion Result Comparison Lower Limit Setting Register (ADLL)280
- A/D Converter Sampling Time Extension Control Register (ADSMPWAIT)281
- Registers for Controlling the Function of the Analog Input Pin Port281
- Input Voltage and Conversion Results282
- Operation Mode of A/D Converter283
- Software Trigger Mode (Select Mode, Continuous Conversion Mode)283
- Software Trigger Mode (Select Mode, Single Conversion Mode)284
- Software Trigger Mode (Scan Mode, Continuous Conversion Mode)285
- Software Trigger Mode (Scan Mode, Single Conversion Mode)286
- Hardware Triggered No-Wait Mode (Select Mode, Continuous Conversion Mode)287
- Hardware Trigger No-Wait Mode (Select Mode, Single Conversion Mode)288
- Hardware Trigger No-Wait Mode (Scan Mode, Continuous Conversion Mode)289
- Hardware Trigger No-Wait Mode (Scan Mode, Single Conversion Mode)290
- Hardware Trigger Wait Mode (Select Mode, Continuous Conversion Mode)291
- Hardware Trigger Wait Mode (Select Mode, Single Conversion Mode)292
- Hardware Trigger Wait Mode (Scan Mode, Continuous Conversion Mode)293
- Hardware Trigger Wait Mode (Scan Mode, Single Conversion Mode)294
Chapter 12 Universal Serial Communication Unit295
- Function of Universal Serial Communication Unit296
- 3-Wire Serial I/O (SSPI00, SSPI01, SSPI10, SSPI11, SSPI20, SSPI21)296
- Uart (Uart0~Uart2)297
- Simple I 2 C (IIC00, IIC01, IIC10, IIC11, IIC20, IIC21)298
- Structure of Universal Serial Communication Unit299
- Shift Register302
- Registers for Controlling Universal Serial Communication Unit304
- Peripheral Enable Register 0 (PER0)305
- Serial Clock Select Register M (Spsm)306
- Serial Mode Register Mn (Smrmn)307
- Serial Communication Operation Setting Register Mn (Scrmn)309
- Serial Data Register Mn (Sdrmn)311
- Serial Flag Clear Trigger Register Mn (Sirmn)313
- Serial Status Register Mn (Ssrmn)314
- Serial Channel Start Register M (Ssm)316
- Serial Channel Stop Register M (Stm)317
- Serial Channel Enable Status Register M (Sem)318
- Serial Output Enable Register M(Soem)319
- Serial Output Register M (Som)320
- Serial Output Level Register M (Solm)321
- Input Switching Control Register (ISC)323
- Noise Filter Enable Register 0 (NFEN0)324
- Registers Controlling the Function of the Serial Input/Output Pin Port325
- Operation Stop Mode326
- Stopping the Operation by Units326
- Stopping the Operation by Channels327
- 3-Wire Serial I/O (SSPI00, SSPI01, SSPI10, SSPI11, SSPI20, SSPI21) Communication328
- Master Transmission329
- Master Reception338
- Master Transmission and Reception346
- Slave Transmission354
- Slave Receiving362
- Slave Send and Receive368
- Calculation of Transmit Clock Frequency377
- Procedure for Handling Errors During 3-Wire Serial I/O Communication (SSPI00, SSPI01, SSPI10, SSPI11, SSPI20, SSPI21)379
- Operation of Clock-Synchronous Serial Communication with Slave Selection Input Function380
- Slave Transmission383
- Slave Receiving393
- Slave Transmission and Reception400
- Calculation of the Transmit Clock Frequency410
- Procedure for Handling Errors During Clock-Synchronous Serial Communication with the Slave Selection Input Function411
- Operation of UART (UART0~UART2) Communication412
- UART Transmission413
- UART Reception422
- Calculation of the Baud Rate429
- Handling Steps When an Error Occurs During UART (UART0~UART 2) Communication433
- Operation of LIN Communication434
- LIN Transmission434
- LIN Reception437
- Simplified I C (IIC00, IIC01, IIC10, IIC11, IIC20, IIC21) Communication Operation442
- Address Segment Transmission443
- Data Transmission448
- Data Reception451
- Generation of Stop Condition455
- Calculation of the Transfer Rate456
- Processing Steps When an Error Occurs in a Simple I2C (IIC00, IIC01, IIC10, IIC11, IIC20, IIC21)458
- Communication Process458
Chapter 13 Serial Interface SPI459
- Serial Interface SPI Function459
- Structure of SPI459
- Registers for Controlling SPI460
- Peripheral Enable Register 0 (PER0)461
- SPI Operating Mode Register (SPIM)462
- SPI Clock Selection Register (SPIC)463
- Transmit Buffer Registers (SDRO)464
- Receive Buffer Register (SDRI)464
- SPI Pin Port Function Control Register465
- Operation of SPI466
- Master Tramission and Reception467
- Master Reception470
- Slave Send and Receive473
- Slave Reception476
Chapter 14 Serial Interface IICA479
- Function of IICA479
- Structure of the Serial Interface IICA482
- Registers for Controlling Serial Interface IICA485
- Peripheral Enable Register 0 (PER0)486
- IICA Control Register N0 (Iicctln0)486
- IICA Status Register N (Iicsn)491
- IICA Flag Register N (Iicfn)493
- IICA Control Register N1 (Iicctln1)495
- IICA Low Level Width Setting Register N (Iicwln)497
- IICA High Level Width Setting Register N (Iicwhn)497
- Registers Controlling the IICA Pin Port Function498
- Function of I C-Bus Mode499
- Pin Structure499
- Setting the Transmit Clock Via Iicwln Register and Iicwhn Register500
- Definition and Control Method of I C-Bus501
- Start Conditions502
- Address503
- Designation of Transmission Direction503
- Acknowledge (ACK)504
- Stop Conditions505
- Wait506
- Release Method of Wait508
- Interrupt Request (Intiican) Generation Timing and Wait Control509
- Detection Method for Address Matching510
- Detection of Errors510
- Extension Code511
- Arbitration512
- Wake-Up Function514
- Communicate with Reservation517
- Other Cautions521
- Communication Operation522
- Generation Timing of I C Interrupt Request (Intiican)531
- Timing Diagram552
Chapter 15 Irda568
- Function of Irda568
- Registers for Controlling the Irda569
- Peripheral Enable Register 0 (PER0)569
- Irda Control Register (IRCR)570
- Operation of Irda571
- Operating Steps for Irda Communication571
- Transmission572
- Reception572
- High Level Pulse Width Selection573
- Considerations When Using Irda573
Chapter 16 Enhanced DMA574
- The Function of DMA574
- Structure of DMA576
- Registers for Controlling DMA577
- DMA Control Data Areas and DMA Vector Table Areas Allocation578
- Control Data Allocation579
- Vector Table581
- Peripheral Enable Register 1 (PER1)583
- DMA Control Register J(Dmacrj) (J=0~23)583
- DMA Block Size Register J (Dmblsj) (J=0~23)585
- DMA Transmit Count Register J(Dmactj) (J=0~23)586
- DMA Transmit Count Reload Register J(Dmrldj) (J=0~23)587
- DMA Source Address Register J(Dmsarj) (J=0~23)588
- DMA Destination Address Register J(Dmdarj) (J=0~23)588
- DMA Boot Enable Register I (Dmaeni) (I=0~2)589
- DMA Base Address Register (DMABAR)591
- DMA Operation592
- Start the Source592
- Normal Mode593
- Repeat Pattern596
- Chain Transfer599
- Precautions When Using DMA601
- DMA Controls the Settings of Data and Vector Tables601
- DMA Controls the Allocation of Data Areas and DMA Vector Table Areas601
- Number of Execution Clocks for DMA602
- Response Time of DMA603
- Startup Source for DMA603
- Operation in Standby Mode604
Chapter 17 Linkage Controller (EVENTC)605
- Feature of EVENTC605
- Structure of EVENTC605
- Control Registers606
- Output Target Selection Register N (Elselrn) (N=00~14)607
- Operation of EVENTC610
Chapter 18 Interrupt Function611
- Types of Interrupt Function611
- Interrupt Source and Structure611
- Registers Controlling Interrupt Function616
- Interrupt Request Flag Registers (IF00 to IF31)616
- Interrupt Mask Flag Register (MK00~MK31)617
- Register (EGN0)618
- Operation of Interrupt Handling622
- Acceptance of Maskable Interrupt Requests622
- Acceptance of Non-Maskable Interrupt Requests622
Chapter 19 Key Interrupt Function623
- Function of Key Interrupt623
- Structure of Key Interrupt623
- Registers for Controlling Key Interrupt625
- Key Return Mode Register (KRM)625
- Port Mode Register (Pmx)626
Chapter 20 Standby Function627
- Standby Function627
- Sleep Mode628
- Setting of the Sleep Mode628
- Release of Sleep Mode631
- Deep Sleep Mode632
- The Setting for Deep Sleep Mode632
- Release of Deep Sleep Mode634
Chapter 21 Reset Function636
- Register for Confirming the Reset Source641
- Reset Control Flag Register (RESF)641
Chapter 22 Power-On Reset Circuit644
- Function of Power-On Reset Circuit644
- Structure of Power-On Reset Circuit645
- Operation of Power-On Reset Circuit645
Chapter 23 Voltage Detection Circuit649
- Function of Voltage Detection Circuit649
- Structure of Voltage Detection Circuit650
- Registers for Controlling Voltage Detection Circuit651
- Voltage Sense Register (LVIM)651
- Voltage Sense Level Register (LVIS)652
- Operation of Voltage Detection Circuit655
- Settings When Used in Reset Mode655
- Settings When Used in Interrupt Mode657
- Settings for Interrupt & Reset Mode659
- Considerations for Voltage Detection Circuits665
Chapter 24 Security Features667
- Overview667
- Registers Used by Security Functions668
- Operation of Security Functions668
- Flash CRC Operation Function (High-Speed CRC)668
- CRC Operation Function (General CRC)672
- RAM Parity Error Detection Function675
- SFR Protection Function677
- Frequency Detection Function678
- A/D Test Function679
- Digital Output Signal Level Detection Function for Input/Output Pin681
- Product Unique Identification Register682
Chapter 25 Temperature Sensor683
- Function of Temperature Sensor683
- Register for Temperature Sensor683
- Temperature Sensor Calibration Data Register TSN25683
- Temperature Sensor Calibration Data Register TSN85683
- Instructions for Use with the Temperature Sensor684
- How the Temperature Sensor Is Used684
- How to Use the Temperature Sensor685
Chapter 26 Option Byte686
- Function of Option Byte686
- User Option Bytes (000C0H~000C2H)686
- Flash Data Protection Option Bytes (000C3H, 500004H)687
- Format of User Option Byte688
- Format of Flash Data Protection Option Bytes694
Chapter 27 FLASH Control695
- Description of FLASH Control695
- Structure of FLASH Memory695
- Registers for Controlling FLASH696
- Flash Write Protection Register (FLPROT)696
- FLASH Operation Control Registers (FLOPMD1, FLOPMD2)697
- Flash Erase Control Register (FLERMD)697
- Flash Status Register (FLSTS)698
- Flash Full-Chip Erase Time Control Register (FLCERCNT)698
- Flash Sector Erase Time Control Register (FLSERCNT)699
- Flash Write Time Control Register (FLPROCNT)700
- FLASH Operation Method701
- Sector Erase701
- Chip Erase702
- Programming (Word Program)702
- Flash Read702
- Cautions for FLASH Operation702
Appendix Revision History703

Cmsemicon CMS32L051 - Calculation of the Baud Rate

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