SWCU193 April   2023 CC2340R2 , CC2340R5 , CC2340R5-Q1

 

  1.   Read This First
    1.     About This Manual
    2.     Devices
    3.     Register, Field, and Bit Calls
    4.     Related Documentation
    5.     Trademarks
  2. 1 Architectural Overview
    1. 1.1  Target Applications
    2. 1.2  Introduction
    3. 1.3  Arm Cortex M0+
      1. 1.3.1 Processor Core
      2. 1.3.2 SysTick Timer
      3. 1.3.3 Nested Vectored Interrupt Controller
      4. 1.3.4 System Control Block (SCB)
    4. 1.4  On-Chip Memory
      1. 1.4.1 SRAM
      2. 1.4.2 FLASH
      3. 1.4.3 ROM
    5. 1.5  Power Supply System
      1. 1.5.1 VDDS
      2. 1.5.2 VDDR
      3. 1.5.3 VDDD Digital Core Supply
      4. 1.5.4 DC/DC Converter
    6. 1.6  Radio
    7. 1.7  AES 128-bit Cryptographic Accelerator
    8. 1.8  System Timer (SYSTIM)
    9. 1.9  General Purpose Timers (LGPT)
    10. 1.10 Always-ON (AON) or Ultra-Low Leakage (ULL) Domain
      1. 1.10.1 Watchdog Timer
      2. 1.10.2 Battery and Temperature Monitor
      3. 1.10.3 Real-time Clock (RTC)
      4. 1.10.4 Low Power Comparator
    11. 1.11 Direct Memory Access
    12. 1.12 System Control and Clock
    13. 1.13 Communication Peripherals
      1. 1.13.1 UART
      2. 1.13.2 I2C
      3. 1.13.3 SPI
    14. 1.14 Programmable I/Os
    15. 1.15 Serial Wire Debug (SWD)
  3. 2  Arm Cortex-M0+ Processor
    1. 2.1 Introduction
    2. 2.2 Block Diagram
    3. 2.3 Overview
      1. 2.3.1 Peripherals
      2. 2.3.2 Programmer's Model
      3. 2.3.3 Instruction Set Summary
      4. 2.3.4 Memory Model
    4. 2.4 Registers
      1. 2.4.1 BPU Registers
      2. 2.4.2 CPU_ROM_TABLE Registers
      3. 2.4.3 DCB Registers
      4. 2.4.4 SCB Registers
      5. 2.4.5 SCSCS Registers
      6. 2.4.6 NVIC Registers
      7. 2.4.7 SYSTICK Registers
  4. 3 Memory Map
    1. 3.1 Memory Map
  5. 4 Interrupts and Events
    1. 4.1 Exception Model
      1. 4.1.1 Exception States
      2. 4.1.2 Exception Types
      3. 4.1.3 Exception Handlers
      4. 4.1.4 Vector Table
      5. 4.1.5 Exception Priorities
      6. 4.1.6 Exception Entry and Return
        1. 4.1.6.1 Exception Entry
        2. 4.1.6.2 Exception Return
    2. 4.2 Fault Handling
      1. 4.2.1 Lockup
    3. 4.3 Event Fabric
      1. 4.3.1 Introduction
      2. 4.3.2 Overview
      3. 4.3.3 Registers
      4. 4.3.4 AON Event Fabric
        1. 4.3.4.1 AON Common Input Events List
        2. 4.3.4.2 AON Event Subscribers
        3. 4.3.4.3 Power Management Controller (PMCTL)
        4. 4.3.4.4 Real Time Clock (RTC)
        5. 4.3.4.5 AON to MCU Event Fabric
      5. 4.3.5 MCU Event Fabric
        1. 4.3.5.1 Common Input Event List
        2. 4.3.5.2 MCU Event Subscribers
          1. 4.3.5.2.1 System CPU
          2. 4.3.5.2.2 Non-Maskable Interrupt (NMI)
    4. 4.4 Digital Test Bus (DTB)
    5. 4.5 EVTULL Registers
    6. 4.6 EVTSVT Registers
  6. 5 Debug Subsystem
    1. 5.1  Introduction
    2. 5.2  Block Diagram
    3. 5.3  Overview
      1. 5.3.1 Physical Interface
      2. 5.3.2 Debug Access Ports
    4. 5.4  Debug Features
      1. 5.4.1 Processor Debug
      2. 5.4.2 Breakpoint Unit (BPU)
      3. 5.4.3 Peripheral Debug
    5. 5.5  Behavior in Low Power Modes
    6. 5.6  Restricting Debug Access
    7. 5.7  Mailbox (DSSM)
    8. 5.8  Mailbox Events
      1. 5.8.1 CPU Interrupt Event (AON_DBG_COMB)
    9. 5.9  Software Considerations
    10. 5.10 DBGSS Registers
  7. 6 Power, Reset, and Clocking
    1. 6.1  Introduction
    2. 6.2  System CPU Modes
    3. 6.3  Supply System
      1. 6.3.1 Internal DC/DC Converter and Global LDO
    4. 6.4  Power States
      1. 6.4.1 RESET
      2. 6.4.2 SHUTDOWN
      3. 6.4.3 ACTIVE
      4. 6.4.4 IDLE
      5. 6.4.5 STANDBY
    5. 6.5  Digital Power Partitioning
    6. 6.6  Clocks
      1. 6.6.1 CLKSVT
      2. 6.6.2 CLKULL
    7. 6.7  Resets
      1. 6.7.1 Watchdog Timer (WDT)
      2. 6.7.2 LF Loss Detection
    8. 6.8  AON (REG3V3) Register Bank
    9. 6.9  CKMD Registers
    10. 6.10 CLKCTL Registers
    11. 6.11 PMCTL Registers
  8. 7 Internal Memory
    1. 7.1 SRAM
    2. 7.2 VIMS
      1. 7.2.1 Introduction
      2. 7.2.2 Block Diagram
      3. 7.2.3 Cache
        1. 7.2.3.1 Basic Cache Mechanism
        2. 7.2.3.2 Cache Prefetch Mechanism
        3. 7.2.3.3 Cache Micro-Prediction Mechanism
      4. 7.2.4 FLASH
        1. 7.2.4.1 FLASH Read-Only Protection
        2. 7.2.4.2 FLASH Memory Programming
      5. 7.2.5 ROM
    3. 7.3 VIMS Registers
    4. 7.4 FLASH Registers
  9. 8 Device Boot and Bootloader
    1. 8.1 Device Boot and Programming
      1. 8.1.1 Boot Flow
      2. 8.1.2 Boot Timing
      3. 8.1.3 Boot Status
      4. 8.1.4 Boot Protection/Locking Mechanisms
      5. 8.1.5 Debug and Active SWD Connections at Boot
      6. 8.1.6 Flashless Test Mode and Tools Client Mode
        1. 8.1.6.1 Flashless Test Mode
        2. 8.1.6.2 Tools Client Mode
      7. 8.1.7 Retest Mode and Return-to-Factory Procedure
      8. 8.1.8 Disabling SWD Debug Port
    2. 8.2 Flash Programming
      1. 8.2.1 CCFG
      2. 8.2.2 CCFG Permissions/Restrictions that Affect Flash Programming
      3. 8.2.3 SACI Flash Programming Commands
      4. 8.2.4 Flash Programming Flows
        1. 8.2.4.1 Initial Programming of a New Device
        2. 8.2.4.2 Reprogramming of Previously Programmed Device
        3. 8.2.4.3 Add User Record on Already Programmed Device as Part of Commissioning Step
        4. 8.2.4.4 Incrementally Program Ancillary Data to MAIN Flash Sectors of a Previously Programmed Device
    3. 8.3 Device Management Command Interface
      1. 8.3.1 SACI Communication Protocol
        1. 8.3.1.1 Host Side Protocol
        2. 8.3.1.2 Command Format
        3. 8.3.1.3 Response Format
        4. 8.3.1.4 Response Result Field
        5. 8.3.1.5 Command Sequence Tag
        6. 8.3.1.6 Host Side Timeout
      2. 8.3.2 SACI Commands
        1. 8.3.2.1 Miscellaneous Commands
          1. 8.3.2.1.1 SACI_CMD_MISC_NO_OPERATION
          2. 8.3.2.1.2 SACI_CMD_MISC_GET_DIE_ID
          3. 8.3.2.1.3 SACI_CMD_MISC_GET_CCFG_USER_REC
        2. 8.3.2.2 Debug Commands
          1. 8.3.2.2.1 SACI_CMD_DEBUG_REQ_PWD_ID
          2. 8.3.2.2.2 SACI_CMD_DEBUG_SUBMIT_AUTH
          3. 8.3.2.2.3 SACI_CMD_DEBUG_EXIT_SACI_HALT
          4. 8.3.2.2.4 SACI_CMD_DEBUG_EXIT_SACI_SHUTDOWN
          5. 8.3.2.2.5 SACI_CMD_BLDR_APP_RESET_DEVICE
          6. 8.3.2.2.6 SACI_CMD_BLDR_APP_EXIT_SACI_RUN
        3. 8.3.2.3 Flash Programming Commands
          1. 8.3.2.3.1 SACI_CMD_FLASH_ERASE_CHIP
          2. 8.3.2.3.2 SACI_CMD_FLASH_PROG_CCFG_SECTOR
          3. 8.3.2.3.3 SACI_CMD_FLASH_PROG_CCFG_USER_REC
          4. 8.3.2.3.4 SACI_CMD_FLASH_PROG_MAIN_SECTOR
          5. 8.3.2.3.5 SACI_CMD_FLASH_PROG_MAIN_PIPELINED
          6. 8.3.2.3.6 SACI_CMD_FLASH_VERIFY_MAIN_SECTORS
          7. 8.3.2.3.7 SACI_CMD_FLASH_VERIFY_CCFG_SECTOR
    4. 8.4 Bootloader Support
      1. 8.4.1 Bootloader Parameters
      2. 8.4.2 Persistent State
      3. 8.4.3 User-Defined Bootloader Guidelines
    5. 8.5 ROM Serial Bootloader
      1. 8.5.1 ROM Serial Bootloader Interfaces
        1. 8.5.1.1 Packet Handling
          1. 8.5.1.1.1 Packet Acknowledge and Not-Acknowledge Bytes
        2. 8.5.1.2 Transport Layer
          1. 8.5.1.2.1 UART Transport
            1. 8.5.1.2.1.1 UART Baud Rate Automatic Detection
          2. 8.5.1.2.2 SPI Transport
      2. 8.5.2 ROM Serial Bootloader Parameters
      3. 8.5.3 ROM Serial Bootloader Commands
        1. 8.5.3.1 BLDR_CMD_PING
        2. 8.5.3.2 BLDR_CMD_GET_STATUS
        3. 8.5.3.3 BLDR_CMD_GET_PART_ID
        4. 8.5.3.4 BLDR_CMD_RESET
        5. 8.5.3.5 BLDR_CMD_CHIP_ERASE
        6. 8.5.3.6 BLDR_CMD_CRC32
        7. 8.5.3.7 BLDR_CMD_DOWNLOAD
        8. 8.5.3.8 BLDR_CMD_DOWNLOAD_CRC
        9. 8.5.3.9 BLDR_CMD_SEND_DATA
      4. 8.5.4 Bootloader Firmware Update Example
  10. 9 Device Configuration
    1. 9.1 Factory Configuration (FCFG)
    2. 9.2 Customer Configuration (CCFG)
  11. 10General Purpose Timers (LGPT)
    1. 10.1 Overview
    2. 10.2 Block Diagram
    3. 10.3 Functional Description
      1. 10.3.1  Prescaler
      2. 10.3.2  Counter
      3. 10.3.3  Target
      4. 10.3.4  Channel Input Logic
      5. 10.3.5  Channel Output Logic
      6. 10.3.6  Channel Actions
        1. 10.3.6.1 Period and Pulse Width Measurement
        2. 10.3.6.2 Clear on Zero, Toggle on Compare Repeatedly
        3. 10.3.6.3 Set on Zero, Toggle on Compare Repeatedly
      7. 10.3.7  Channel Capture Configuration
      8. 10.3.8  Channel Filters
        1. 10.3.8.1 Setting up the Channel Filters
      9. 10.3.9  Synchronize Multiple LGPT Timers
      10. 10.3.10 Interrupts, ADC Trigger, and DMA Request
    4. 10.4 Timer Modes
      1. 10.4.1 Quadrature Decoder
      2. 10.4.2 DMA
      3. 10.4.3 IR Generation
      4. 10.4.4 Fault and Park
      5. 10.4.5 Dead-Band
      6. 10.4.6 Dead-Band, Fault and Park
      7. 10.4.7 Example Application: Brushless DC (BLDC) Motor
    5. 10.5 LGPT0 Registers
    6. 10.6 LGPT1 Registers
    7. 10.7 LGPT2 Registers
    8. 10.8 LGPT3 Registers
  12. 11System Timer (SYSTIM)
    1. 11.1 Overview
    2. 11.2 Block Diagram
    3. 11.3 Functional Description
      1. 11.3.1 Common Channel Features
        1. 11.3.1.1 Compare Mode
        2. 11.3.1.2 Capture Mode
        3. 11.3.1.3 Additional Channel Arming Methods
      2. 11.3.2 Interrupts and Events
    4. 11.4 SYSTIM Registers
  13. 12Real Time Clock (RTC)
    1. 12.1 Introduction
    2. 12.2 Block Diagram
    3. 12.3 Interrupts and Events
      1. 12.3.1 Input Event
      2. 12.3.2 Output Event
      3. 12.3.3 Arming and Disarming Channels
    4. 12.4 Capture and Compare Configuration
      1. 12.4.1 Capture
      2. 12.4.2 Compare
    5. 12.5 RTC Registers
  14. 13Low Power Comparator
    1. 13.1 Introduction
    2. 13.2 Block Diagram
    3. 13.3 Functional Description
      1. 13.3.1 Input Selection
      2. 13.3.2 Voltage Divider
      3. 13.3.3 Hysteresis
      4. 13.3.4 Wake-up
    4. 13.4 SYS0 Registers
  15. 14Battery Monitor, Temperature Sensor, and DCDC Controller (PMUD)
    1. 14.1 Introduction
    2. 14.2 Functional Description
      1. 14.2.1 BATMON
      2. 14.2.2 DCDC
    3. 14.3 PMUD Registers
  16. 15Micro Direct Memory Access (µDMA)
    1. 15.1 Introduction
    2. 15.2 Block Diagram
    3. 15.3 Functional Description
      1. 15.3.1  Channel Assignments
      2. 15.3.2  Priority
      3. 15.3.3  Arbitration Size
      4. 15.3.4  Request Types
        1. 15.3.4.1 Single Request
        2. 15.3.4.2 Burst Request
      5. 15.3.5  Channel Configuration
      6. 15.3.6  Transfer Modes
        1. 15.3.6.1 Stop Mode
        2. 15.3.6.2 Basic Mode
        3. 15.3.6.3 Auto Mode
        4. 15.3.6.4 Ping-Pong Mode
        5. 15.3.6.5 Memory Scatter-Gather Mode
        6. 15.3.6.6 Peripheral Scatter-Gather Mode
      7. 15.3.7  Transfer Size and Increments
      8. 15.3.8  Peripheral Interface
      9. 15.3.9  Software Request
      10. 15.3.10 Interrupts and Errors
      11. 15.3.11 Initialization and Configuration
        1. 15.3.11.1 Module Initialization
        2. 15.3.11.2 Configuring a Memory-to-Memory Transfer
        3. 15.3.11.3 Configure the Channel Attributes
        4. 15.3.11.4 Configure the Channel Control Structure
        5. 15.3.11.5 Start the Transfer
        6. 15.3.11.6 Software Considerations
    4. 15.4 DMA Registers
  17. 16Advanced Encryption Standard (AES)
    1. 16.1 Introduction
      1. 16.1.1 AES Performance
    2. 16.2 Functional Description
      1. 16.2.1 Reset Considerations
      2. 16.2.2 Interrupt and Event Support
        1. 16.2.2.1 Interrupt Events and Requests
        2. 16.2.2.2 Connection to Event Fabric
      3. 16.2.3 µDMA
        1. 16.2.3.1 µDMA Example
    3. 16.3 Encryption and Decryption Configuration
      1. 16.3.1  CBC-MAC (Cipher Block Chaining-Message Authentication Code)
      2. 16.3.2  CBC (Cipher Block Chaining) Encryption
      3. 16.3.3  CBC Decryption
      4. 16.3.4  CTR (Counter) Encryption/Decryption
      5. 16.3.5  ECB (Electronic Code Book) Encryption
      6. 16.3.6  ECB Decryption
      7. 16.3.7  CFB (Cipher Feedback) Encryption
      8. 16.3.8  CFB Decryption
      9. 16.3.9  OFB (Open Feedback) Encryption
      10. 16.3.10 OFB Decryption
      11. 16.3.11 PCBC (Propagating Cipher Block Chaining) Encryption
      12. 16.3.12 PCBC Decryption
      13. 16.3.13 CTR-DRBG (Counter-Deterministic Random Bit Generator)
      14. 16.3.14 CCM
    4. 16.4 AES Registers
  18. 17Analog to Digital Converter (ADC)
    1. 17.1 Overview
    2. 17.2 Block Diagram
    3. 17.3 Functional Description
      1. 17.3.1  ADC Core
      2. 17.3.2  Voltage Reference Options
      3. 17.3.3  Resolution Modes
      4. 17.3.4  ADC Clocking
      5. 17.3.5  Power Down Behavior
      6. 17.3.6  Sampling Trigger Sources and Sampling Modes
        1. 17.3.6.1 AUTO Sampling Mode
        2. 17.3.6.2 MANUAL Sampling Mode
      7. 17.3.7  Sampling Period
      8. 17.3.8  Conversion Modes
      9. 17.3.9  ADC Data Format
      10. 17.3.10 Status Register
      11. 17.3.11 ADC Events
        1. 17.3.11.1 CPU Interrupt Event Publisher (INT_EVENT0)
        2. 17.3.11.2 Generic Event Publisher (INT_EVENT1)
        3. 17.3.11.3 DMA Trigger Event Publisher (INT_EVENT2)
        4. 17.3.11.4 Generic Event Subscriber
    4. 17.4 Advanced Features
      1. 17.4.1 Window Comparator
      2. 17.4.2 DMA & FIFO Operation
        1. 17.4.2.1 DMA/CPU Operation in Non-FIFO Mode (FIFOEN=0)
        2. 17.4.2.2 DMA/CPU Operation in FIFO Mode (FIFOEN=1)
        3. 17.4.2.3 DMA/CPU Operation Summary Matrix
      3. 17.4.3 Ad-hoc Single Conversion
    5. 17.5 ADC Registers
  19. 18I/O Controller (IOC)
    1. 18.1  Introduction
    2. 18.2  Block Diagram
    3. 18.3  I/O Mapping and Configuration
      1. 18.3.1 Basic I/O Mapping
      2. 18.3.2 Radio GPO
      3. 18.3.3 Pin Mapping
      4. 18.3.4 DTB Muxing
    4. 18.4  Edge Detection
    5. 18.5  GPIO
    6. 18.6  I/O Pins
    7. 18.7  Unused Pins
    8. 18.8  Debug Configuration
    9. 18.9  IOC Registers
    10. 18.10 GPIO Registers
  20. 19Universal Asynchronous Receiver/Transmitter (UART)
    1. 19.1 Introduction
    2. 19.2 Block Diagram
    3. 19.3 Functional Description
      1. 19.3.1 Transmit and Receive Logic
      2. 19.3.2 Baud Rate Generation
      3. 19.3.3 FIFO Operation
        1. 19.3.3.1 FIFO Remapping
      4. 19.3.4 Data Transmission
      5. 19.3.5 Flow Control
      6. 19.3.6 IrDA Encoding and Decoding
      7. 19.3.7 Interrupts
      8. 19.3.8 Loopback Operation
    4. 19.4 Interface to µDMA
    5. 19.5 Initialization and Configuration
    6. 19.6 UART Registers
  21. 20Serial Peripheral Interface (SPI)
    1. 20.1 Overview
      1. 20.1.1 Features
      2. 20.1.2 Block Diagram
    2. 20.2 Signal Description
    3. 20.3 Functional Description
      1. 20.3.1  Clock Control
      2. 20.3.2  FIFO Operation
        1. 20.3.2.1 Transmit FIFO
        2. 20.3.2.2 Repeated Transmit Operation
        3. 20.3.2.3 Receive FIFO
        4. 20.3.2.4 FIFO Flush
      3. 20.3.3  Interrupts
      4. 20.3.4  Data Format
      5. 20.3.5  Delayed Data Sampling
      6. 20.3.6  Chip Select Control
      7. 20.3.7  Command Data Control
      8. 20.3.8  Protocol Descriptions
        1. 20.3.8.1 Motorola SPI Frame Format
        2. 20.3.8.2 Texas Instruments Synchronous Serial Frame Format
        3. 20.3.8.3 MICROWIRE Frame Format
      9. 20.3.9  CRC Configuration
      10. 20.3.10 Auto CRC Functionality
      11. 20.3.11 Auto Header Functionality
      12. 20.3.12 SPI Status
      13. 20.3.13 Debug Halt
    4. 20.4 µDMA Operation
    5. 20.5 Initialization and Configuration
    6. 20.6 SPI Registers
  22. 21Inter-Integrated Circuit (I2C)
    1. 21.1 Introduction
    2. 21.2 Block Diagram
    3. 21.3 Functional Description
      1. 21.3.1 Functional Overview
        1. 21.3.1.1 Start and Stop Conditions
        2. 21.3.1.2 Data Format with 7-Bit Address
        3. 21.3.1.3 Data Validity
        4. 21.3.1.4 Acknowledge
        5. 21.3.1.5 Arbitration
      2. 21.3.2 Available Speed Modes
      3. 21.3.3 Interrupts
        1. 21.3.3.1 I2C Controller Interrupts
        2. 21.3.3.2 I2C Target Interrupts
      4. 21.3.4 Loopback Operation
      5. 21.3.5 Command Sequence Flow Charts
        1. 21.3.5.1 I2C Controller Command Sequences
        2. 21.3.5.2 I2C Target Command Sequences
    4. 21.4 Initialization and Configuration
    5. 21.5 I2C Registers
  23. 22Radio
    1. 22.1 Introduction
    2. 22.2 Block Diagram
    3. 22.3 Overview
      1. 22.3.1 Radio Sub-domains
      2. 22.3.2 Radio RAMs
      3. 22.3.3 Doorbell (DBELL)
        1. 22.3.3.1 Interrupts
        2. 22.3.3.2 GPIO Control
        3. 22.3.3.3 SYSTIM Interface
    4. 22.4 Radio Usage Model
      1. 22.4.1 CRC and Whitening
    5. 22.5 LRFDDBELL Registers
    6. 22.6 LRFDRXF Registers
    7. 22.7 LRFDTXF Registers

19.3.6 IrDA Encoding and Decoding

When the UART.CTL[1] SIREN bit is set, the IrDA (SIR) encoder and decoder are enabled and provide hardware bit shaping for IrDA communication. In this protocol, from the transmitter perspective, a zero is transmitted as a high pulse and a one is transmitted as a zero.

The width of the pulse is specified as 3/16th of the selected bit period. The SIR decoder converts the IrDA compliant receive signal into a bit stream for the UART core. The SIR receive logic interprets a high state as a logic one and low pulses as logic zeros. For more details please refer to the SIR Physical Layer Link Specification Version 1.1

Setting the UART.CTL SIRLP[2] bit enables low power mode. In the low power mode, the width of the pulse is set to 3 times the time period of the IrLPBaud16 signal. The IrLPBaud16 signal is generated by dividing down the CLKSVT (48MHz) according to the low-power divisor value written to the UARTILPR register. The low-power divisor value is calculated as follows:

Equation 6. low-power divisor (ILPDVSR) = (CLKSVT / (FIrLPBaud16 * 3))

where FIrLPBaud16 is nominally 1.8432 MHz.

The divisor must be selected such that 1.42 MHz < FIrLPBaud16 < 2.12 MHz, results in a low-power pulse duration of 1.41-2.11μs (three times the period of IrLPBaud16).

Note: In low-power IrDA mode the UART rejects random noise on the received serial data input by ignoring SIRIN pulses that are less than 3 periods of IrLPBaud16.

The time period of the nSIROUT bit stream is still equal to the programmed bit period and is governed by the period of the Baud16 signal.

In the low power mode, there is an upper limit on the allowable bit rate if the integrity of the IrDA pulse stream is to be maintained. The upper limit is determined by the requirement that the width of 3 times the period of the IrLPBaud16 signal is less than one bit period. With a nominal IrLPBaud16 frequency of 2 MHz, this translates to a maximum allowable baud rate of 666.6 Kbps. This is not a problem since the specification states that the UART is to support bit rates of only up to 115.2 Kbps for the SIR endec.

If the low power mode of the IrDA is used, there is also a lower limit on the frequency of CLKSVT. The reload value for the IrLPBaud16 counter can be a minimum of 1. Given that IrLPBaud16 needs to have a minimum frequency of 1.42 MHz to satisfy IrDA requirements, CLKSVT needs to be at least 1.42 MHz to meet the minimum pulse width requirement. In the case of transmission, the IrLPBaud16 signal is used to control the width of the transmit pulse stream only in the low power mode. On the other hand, in the case of reception, the IrLPBaud16 signal is used to sample the pulses in the input SIRIN stream both in the normal mode and in the low power mode. Thus, the IrLPBaud16 signal is generated irrespective of whether the IrDA section is programmed to operate in the normal mode or in the low power mode but the signal is not generated when both IrDA modes are disabled.

The SIR receiver section contains a 4-bit binary counter, which operates on CLKSVT in the normal mode with the Baud16 signal as an enable signal. When the input SIRIN signal is high, the decoded output signal, RXD, is driven high to indicate a 1. A low on the SIRIN line is sampled multiple times on IrLPBaud16 for glitch rejection and converted into a low on the RXD line. The time period for which the RXD line is pulled low corresponds to approximately one bit period at the programmed bit rate. After the counter rolls over, input sampling restarts. The SIRLPSync signal is the CLKSVT-synchronised version of the SIRLP mode selection bit in the UART.CTL register. This signal determines the IrDA encoding strategy i.e. whether the IrDA transmitter block is to operate in the normal mode or in the low power mode. The SIRENSync signal is the SIREN bit in the UART.CTL register, which has been synchronised to CLKSVT. This signal enables / disables the SIR section.