SLAU962A December   2025  – June 2026 MSPM33C321A , MSPM33C321A-Q1

 

  1.   1
  2.   Read This First
    1.     About This Manual
    2.     Notational Conventions
    3.     Glossary
    4.     Related Documentation
    5.     Support Resources
    6.     Trademarks
  3. 1 Architecture
    1. 1.1 Architecture Overview
    2. 1.2 Bus Organization
    3. 1.3 Platform Memory Map
      1. 1.3.1 Code Region
      2. 1.3.2 SRAM Region
      3. 1.3.3 Peripheral Region
      4. 1.3.4 System PPB Region
    4. 1.4 Boot Configuration
      1. 1.4.1 Configuration Memory
      2. 1.4.2 NON_MAIN_Configuration Registers
    5. 1.5 Factory Constants
      1. 1.5.1 FACTORYREGION Registers
    6. 1.6 Memory configuration
      1. 1.6.1 memcfg Registers
  4. 2  PMCU
    1. 2.1 PMCU Overview
      1. 2.1.1 Power Domains
      2. 2.1.2 Operating Modes
        1. 2.1.2.1 RUN Mode
        2. 2.1.2.2 SLEEP Mode
        3. 2.1.2.3 STOP Mode
        4. 2.1.2.4 STANDBY Mode
        5. 2.1.2.5 SHUTDOWN Mode
        6. 2.1.2.6 Suspended Low-Power Mode Operation
    2. 2.2 Power Management (PMU)
      1. 2.2.1 Power Supply
      2. 2.2.2 Core Regulator
      3. 2.2.3 Supply Supervisors
        1. 2.2.3.1 Power-on Reset (POR)
        2. 2.2.3.2 Brownout Reset (BOR)
        3. 2.2.3.3 POR and BOR Behavior During Supply Changes
      4. 2.2.4 Bandgap Reference
      5. 2.2.5 VBOOST for Analog Muxes
      6. 2.2.6 Peripheral Enable
        1. 2.2.6.1 Automatic Peripheral Disable in Low Power Modes
    3. 2.3 Clock Module (CKM)
      1. 2.3.1 Oscillators
        1. 2.3.1.1 Internal Low-Frequency Oscillator (LFOSC)
        2. 2.3.1.2 Internal System Oscillator (SYSOSC)
          1. 2.3.1.2.1 SYSOSC Gear Shift
          2. 2.3.1.2.2 SYSOSC Frequency and User Trims
          3. 2.3.1.2.3 SYSOSC Frequency Correction Loop
            1. 2.3.1.2.3.1 SYSOSC FCL in Internal Resistor Mode
        3. 2.3.1.3 System Phase-Locked Loop (SYSPLL)
          1. 2.3.1.3.1 Configuring SYSPLL Output Frequencies
          2. 2.3.1.3.2 Loading SYSPLL Lookup Parameters
          3. 2.3.1.3.3 SYSPLL Startup Time
        4. 2.3.1.4 Low Frequency Crystal Oscillator (LFXT)
        5. 2.3.1.5 LFCLK_IN (Digital Clock)
        6. 2.3.1.6 High Frequency Crystal Oscillator (HFXT)
        7. 2.3.1.7 HFCLK_IN (Digital clock)
      2. 2.3.2 Clocks
        1. 2.3.2.1  MCLK (Main Clock) Tree
        2. 2.3.2.2  MCLK/2 (Half Clock)
        3. 2.3.2.3  MCLK/4 (Quarter Clock)
        4. 2.3.2.4  CPUCLK (Processor Clock)
        5. 2.3.2.5  ULPCLK (Low-Power Clock)
        6. 2.3.2.6  MFCLK (Middle Frequency Clock)
        7. 2.3.2.7  LFCLK (Low-Frequency Clock)
        8. 2.3.2.8  HFCLK (High-Frequency External Clock)
        9. 2.3.2.9  CANCLK (CAN-FD Functional Clock)
        10. 2.3.2.10 I2SCLK (I2S Functional Clock)
        11. 2.3.2.11 RTCCLK (RTC Clock)
        12. 2.3.2.12 External Clock Output (CLK_OUT)
        13. 2.3.2.13 Direct Clock Connections for Infrastructure
      3. 2.3.3 Clock Tree
        1. 2.3.3.1 Peripheral Clock Source Selection
    4. 2.4 Clock Monitors
      1. 2.4.1 LFCLK Monitor
      2. 2.4.2 MCLK Monitor
      3. 2.4.3 Startup Monitors
        1. 2.4.3.1 LFOSC Startup Monitor
        2. 2.4.3.2 LFXT Startup Monitor
        3. 2.4.3.3 HFCLK Startup Monitor
        4. 2.4.3.4 SYSPLL Startup Monitor
        5. 2.4.3.5 HSCLK Status
    5. 2.5 Frequency Clock Counter (FCC)
      1. 2.5.1 Using the FCC
      2. 2.5.2 FCC Frequency Computation and Accuracy
    6. 2.6 System Controller (SYSCTL)
      1. 2.6.1 Resets and Device Initialization
        1. 2.6.1.1 Reset Levels
          1. 2.6.1.1.1 Power-on Reset (POR) Reset Level
          2. 2.6.1.1.2 Brownout Reset (BOR) Reset Level
          3. 2.6.1.1.3 Boot Reset (BOOTRST) Reset Level
          4. 2.6.1.1.4 System Reset (SYSRST) Reset Level
          5. 2.6.1.1.5 CPU-only Reset (CPURST) Reset Level
        2. 2.6.1.2 Initial Conditions After Power-Up
        3. 2.6.1.3 NRST Pin
        4. 2.6.1.4 SWD Pins
        5. 2.6.1.5 Generating Resets in Software
        6. 2.6.1.6 Reset Cause
        7. 2.6.1.7 Peripheral Reset Control
        8. 2.6.1.8 Boot Fail Handling
      2. 2.6.2 Operating Mode Selection
      3. 2.6.3 Asynchronous Fast Clock Requests
      4. 2.6.4 Flash Bank Address Swap
      5. 2.6.5 Shutdown Mode Handling (if present)
      6. 2.6.6 Configuration Lockout
      7. 2.6.7 System Status
      8. 2.6.8 Error Handling
      9. 2.6.9 SYSCTL Events
        1. 2.6.9.1 CPU Interrupt Event (CPU_INT)
        2. 2.6.9.2 Nonmaskable Interrupt Event (NMI)
    7. 2.7 Quick Start Reference
      1. 2.7.1 Default Device Configuration
      2. 2.7.2 Leveraging MFCLK
      3. 2.7.3 Optimizing Power Consumption in STOP Mode
      4. 2.7.4 Optimizing Power Consumption in STANDBY Mode
      5. 2.7.5 Increasing MCLK and ULPCLK Precision
      6. 2.7.6 Configuring MCLK for Maximum Speed
      7. 2.7.7 High Speed Clock (SYSPLL, HFCLK) Handling in Low-Power Modes
      8. 2.7.8 Optimizing for Lowest Wakeup Latency
    8. 2.8 SYSCTL Registers
  5. 3  CPU
    1. 3.1 Overview
    2. 3.2 CPU
      1. 3.2.1 Arm Cortex-M33 CPU
      2. 3.2.2 CPU Register File
      3. 3.2.3 Stack Behavior
      4. 3.2.4 Execution Modes and Privilege Levels
      5. 3.2.5 Address Space and Supported Data Sizes
      6. 3.2.6 Secure memory partitioning
    3. 3.3 Interrupts and Exceptions
      1. 3.3.1 Peripheral Interrupts (IRQs)
        1. 3.3.1.1 Nested Vectored Interrupt Controller (NVIC)
        2. 3.3.1.2 Wake Up Controller (WUC)
      2. 3.3.2 Interrupt and Exception Table
      3. 3.3.3 Processor Lockup Scenario
    4. 3.4 CPU Peripherals
      1. 3.4.1 System Control Block (SCB)
      2. 3.4.2 System Tick Timer (SysTick)
      3. 3.4.3 Memory Protection Unit (MPU)
      4. 3.4.4 Security Attribute Unit
      5. 3.4.5 Implementation Defined Attribution Unit (IDAU)
      6. 3.4.6 Floating Point Unit (FPU)
      7. 3.4.7 Digital Signal Processing Extension
    5. 3.5 Read-Only Memory (ROM)
  6. 4 Secure ROM
    1. 4.1 ROM Overview
    2. 4.2 Memory Map
    3. 4.3 Boot Configuration Routine (BCR)
      1. 4.3.1 SWD Mass Erase and Factory Reset Commands
      2. 4.3.2 Application HASH Verification
      3. 4.3.3 Fast Boot
    4. 4.4 Bootstrap Loader (BSL)
      1. 4.4.1 Application Version
      2. 4.4.2 GPIO Invoke
      3. 4.4.3 BSL Triggered Mass Erase and Factory Reset
    5. 4.5 Lifecycle Management
      1. 4.5.1 Device Sub-Type
      2. 4.5.2 Lifecycle Transitions
    6. 4.6 Boot and Startup Sequence
      1. 4.6.1 Secure Boot
      2. 4.6.2 Customer Secure Code (CSC)
  7. 5 NVM (Flash)
    1. 5.1 NVM Overview
      1. 5.1.1 Key Features
      2. 5.1.2 System Components
      3. 5.1.3 Terminology
    2. 5.2 Flash Memory Bank Organization
      1. 5.2.1 Banks
      2. 5.2.2 Flash Memory Regions
      3. 5.2.3 Addressing
        1. 5.2.3.1 Flash Memory Map
    3. 5.3 Flash Controller
      1. 5.3.1 Overview of Flash Controller Commands
      2. 5.3.2 NOOP Command
      3. 5.3.3 PROGRAM Command
        1. 5.3.3.1 Program Bit Masking Behavior
        2. 5.3.3.2 Programming Less Than One Flash Word
        3. 5.3.3.3 Target Data Alignment (Devices with Single Flash Word Programming Only)
        4. 5.3.3.4 Target Data Alignment (Devices With Multiword Programming)
        5. 5.3.3.5 Executing a PROGRAM Operation
      4. 5.3.4 ERASE Command
        1. 5.3.4.1 Erase Sector Masking Behavior
        2. 5.3.4.2 Executing an ERASE Operation
      5. 5.3.5 READVERIFY Command
        1. 5.3.5.1 Executing a READVERIFY Operation
      6. 5.3.6 Command Diagnostics
        1. 5.3.6.1 Command Status
        2. 5.3.6.2 Address Translation
        3. 5.3.6.3 Pulse Counts
      7. 5.3.7 Overriding the System Address With a Bank ID, Region ID, and Bank Address
    4. 5.4 Flash Programming Interface
      1. 5.4.1 Flash Resource Ownership Check
      2. 5.4.2 Authorization Check
      3. 5.4.3 FPI SEC Error Handling
      4. 5.4.4 Bank Erase Protection
    5. 5.5 Flash Read Interface
      1. 5.5.1 Bank Address Swapping
      2. 5.5.2 ECC Error Handling
        1. 5.5.2.1 Single bit (correctable) errors
        2. 5.5.2.2 Dual bit (uncorrectable) errors
      3. 5.5.3 GSC SEC Error Handling
    6. 5.6 FLASHCTL Registers
    7. 5.7 FRI Registers
  8. 6 EAM
    1. 6.1 EAM Introduction
    2. 6.2 EAM Operation
      1. 6.2.1 Security Error Aggregator
      2. 6.2.2 Safety Error Aggregator
    3. 6.3 EAM Registers
  9. 7 Direct Memory Access (DMA)
    1. 7.1 DMA Overview
    2. 7.2 DMA Operation
      1. 7.2.1  Addressing Modes
      2. 7.2.2  Channel Types
      3. 7.2.3  Transfer Modes
        1. 7.2.3.1 Single Transfer
        2. 7.2.3.2 Block Transfer
        3. 7.2.3.3 Repeated Single Transfer
        4. 7.2.3.4 Repeated Block Transfer
        5. 7.2.3.5 Stride Mode
      4. 7.2.4  Extended Modes
        1. 7.2.4.1 Fill Mode
        2. 7.2.4.2 Table Mode
      5. 7.2.5  Initiating DMA Transfers
      6. 7.2.6  Stopping DMA Transfers
      7. 7.2.7  Channel Priorities
      8. 7.2.8  Burst Block Mode
      9. 7.2.9  Using DMA with System Interrupts
      10. 7.2.10 DMA Controller Interrupts
      11. 7.2.11 DMA Trigger Event Status
      12. 7.2.12 DMA Operating Mode Support
        1. 7.2.12.1 Transfer in RUN Mode
        2. 7.2.12.2 Transfer in SLEEP Mode
      13. 7.2.13 DMA Address and Data Errors
      14. 7.2.14 Interrupt and Event Support
    3. 7.3 DMA Registers
  10. 8 Events
    1. 8.1 Events Overview
      1. 8.1.1 Event Publisher
      2. 8.1.2 Event Subscriber
      3. 8.1.3 Event Fabric Routing
        1. 8.1.3.1 CPU Interrupt Event Route (CPU_INT)
        2. 8.1.3.2 DMA Trigger Event Route (DMA_TRIGx)
        3. 8.1.3.3 Generic Event Route (GEN_EVENTx)
      4. 8.1.4 Event Routing Map
      5. 8.1.5 Event Propagation Latency
    2. 8.2 Events Operation
      1. 8.2.1 CPU Interrupt
      2. 8.2.2 DMA Trigger
      3. 8.2.3 Peripheral to Peripheral Event
      4. 8.2.4 Extended Module Description Register
      5. 8.2.5 Using Event Registers
        1. 8.2.5.1 Event Registers
        2. 8.2.5.2 Configuring Events
        3. 8.2.5.3 Responding to CPU Interrupts in Application Software
        4. 8.2.5.4 Hardware Event Handling
  11. 9 IOMUX
    1. 9.1 IOMUX Overview
      1. 9.1.1 IO Types and Analog Sharing
    2. 9.2 IOMUX Operation
      1. 9.2.1 Peripheral Function (PF) Assignment
      2. 9.2.2 Logic High to Hi-Z Conversion
      3. 9.2.3 Logic Inversion
      4. 9.2.4 SHUTDOWN Mode Wakeup Logic
      5. 9.2.5 Pullup/Pulldown Resistors
      6. 9.2.6 Drive Strength Control
      7. 9.2.7 Hysteresis and Logic Level Control
    3. 9.3 IOMUX Registers
  12. 10General-Purpose Input/Output (GPIO)
    1. 10.1 GPIO Overview
    2. 10.2 GPIO Operation
      1. 10.2.1 GPIO Ports
      2. 10.2.2 GPIO Read/Write Interface
      3. 10.2.3 GPIO Input Glitch Filtering and Synchronization
      4. 10.2.4 GPIO Fast Wake
      5. 10.2.5 Event Publishers and Subscribers
    3. 10.3 GPIO Registers
  13. 11Global Security Controller
    1. 11.1 GSC Introduction
      1. 11.1.1 GSC Features
    2. 11.2 GSC Operation
      1. 11.2.1 Functional Block Diagram
      2. 11.2.2 Peripheral Protection Controller
        1. 11.2.2.1 DMA controller security
      3. 11.2.3 SRAM Protection Controller
        1. 11.2.3.1 SRAM Page Use Model
      4. 11.2.4 Flash Protection Controller
        1. 11.2.4.1 Flash Bank Security Implementation
        2. 11.2.4.2 Flash Hide Protection
      5. 11.2.5 Strict Secure and Privilege Context Protection
      6. 11.2.6 GSC Configuration Lock
    3. 11.3 GSC Registers
  14. 12PKA
    1. 12.1 PKA Introduction
      1. 12.1.1 PKA features
    2. 12.2 PKA Operation
      1. 12.2.1 Functional Block Diagram
      2. 12.2.2 Theory of Operations
        1. 12.2.2.1 PKCP
        2. 12.2.2.2 Sequencer
      3. 12.2.3 Complex Commands
      4. 12.2.4 Command Execution and Status
      5. 12.2.5 Initialization
      6. 12.2.6 Interrupts support
        1. 12.2.6.1 Interrupt Sources
    3. 12.3 PKA Registers
  15. 13AESADV
    1. 13.1 AES Overview
      1. 13.1.1 AESADV Performance
    2. 13.2 AESADV Operation
      1. 13.2.1 Loading the Key
      2. 13.2.2 Writing Input Data
      3. 13.2.3 Reading Output Data
      4. 13.2.4 Operation Descriptions
        1. 13.2.4.1 Single Block Operation
        2. 13.2.4.2 Electronic Codebook (ECB) Mode
          1. 13.2.4.2.1 ECB Encryption
          2. 13.2.4.2.2 ECB Decryption
        3. 13.2.4.3 Cipher Block Chaining (CBC) Mode
          1. 13.2.4.3.1 CBC Encryption
          2. 13.2.4.3.2 CBC Decryption
        4. 13.2.4.4 Output Feedback (OFB) Mode
          1. 13.2.4.4.1 OFB Encryption
          2. 13.2.4.4.2 OFB Decryption
        5. 13.2.4.5 Cipher Feedback (CFB) Mode
          1. 13.2.4.5.1 CFB Encryption
          2. 13.2.4.5.2 CFB Decryption
        6. 13.2.4.6 Counter (CTR) Mode
          1. 13.2.4.6.1 CTR Encryption
          2. 13.2.4.6.2 CTR Decryption
        7. 13.2.4.7 Galois Counter (GCM) Mode
          1. 13.2.4.7.1 GHASH Operation
          2. 13.2.4.7.2 GCM Operating Modes
            1. 13.2.4.7.2.1 Autonomous GCM Operation
              1. 13.2.4.7.2.1.1 GMAC
            2. 13.2.4.7.2.2 GCM With Pre-Calculations
            3. 13.2.4.7.2.3 GCM Operation With Precalculated H- and Y0-Encrypted Forced to Zero
        8. 13.2.4.8 Counter With Cipher Block Chaining Message Authentication Code (CCM)
          1. 13.2.4.8.1 CCM Operation
      5. 13.2.5 AES Events
        1. 13.2.5.1 CPU Interrupt Event Publisher (CPU_EVENT)
        2. 13.2.5.2 DMA Trigger Event Publisher (DMA_TRIG_DATAIN)
        3. 13.2.5.3 DMA Trigger Event Publisher (DMA_TRIG_DATAOUT)
    3. 13.3 AESADV Registers
  16. 14SHA2
    1. 14.1 SHA Introduction
      1. 14.1.1 SHA features
    2. 14.2 SHA Operation
      1. 14.2.1 Functional Block Diagram
      2. 14.2.2 HMAC Controller
      3. 14.2.3 HASH/HMAC Engine
        1. 14.2.3.1 HMAC processing with MAC Key Input
        2. 14.2.3.2 HMAC processing with digest
        3. 14.2.3.3 HMAC processing with reload digest
    3. 14.3 SHA Auto-Feed Mode
    4. 14.4 SHA Registers
  17. 15CRC
    1. 15.1 CRC Overview
      1. 15.1.1 CRC16-CCITT
      2. 15.1.2 CRC32-ISO3309
    2. 15.2 CRC Operation
      1. 15.2.1 CRC Generator Implementation
      2. 15.2.2 Configuration
        1. 15.2.2.1 Polynomial Selection
        2. 15.2.2.2 Bit Order
        3. 15.2.2.3 Byte Swap
        4. 15.2.2.4 Byte Order
        5. 15.2.2.5 CRC C Library Compatibility
    3. 15.3 CRCP0 Registers
  18. 16Keystore
    1. 16.1 Overview
    2. 16.2 Detailed Description
    3. 16.3 KEYSTORECTL Registers
  19. 17TRNG
    1. 17.1 TRNG Overview
    2. 17.2 TRNG Operation
      1. 17.2.1 TRNG Generation Data Path
      2. 17.2.2 Clock Configuration and Output Rate
      3. 17.2.3 Behavior in Low Power Modes
      4. 17.2.4 Health Tests
        1. 17.2.4.1 Digital Block Startup Self-Test
        2. 17.2.4.2 Analog Block Startup Self-Test
        3. 17.2.4.3 Runtime Health Test
          1. 17.2.4.3.1 Repetition Count Test
          2. 17.2.4.3.2 Adaptive Proportion Test
          3. 17.2.4.3.3 Handling Runtime Health Test Failures
      5. 17.2.5 Configuration
        1. 17.2.5.1 TRNG State Machine
          1. 17.2.5.1.1 Changing TRNG States
        2. 17.2.5.2 Using the TRNG
        3. 17.2.5.3 TRNG Events
          1. 17.2.5.3.1 CPU Interrupt Event Publisher (CPU_INT)
    3. 17.3 TRNG Registers
  20. 18HSADC
    1. 18.1 Introduction
      1. 18.1.1 Features
      2. 18.1.2 Block Diagram
    2. 18.2 HSADC Operation
      1. 18.2.1 ADC Configurability
        1. 18.2.1.1 ADC Clock Configuration
        2. 18.2.1.2 Voltage Reference
        3. 18.2.1.3 Signal Mode
          1. 18.2.1.3.1 Expected Conversion Results
          2. 18.2.1.3.2 Interpreting Conversion Results
      2. 18.2.2 SOC Principle of Operation
        1. 18.2.2.1 HSADC Sequencer Operation
        2. 18.2.2.2 SOC Configuration
        3. 18.2.2.3 Trigger Operation
        4. 18.2.2.4 ADC Acquisition (Sample and Hold) Window
        5. 18.2.2.5 Sample Capacitor Reset
        6. 18.2.2.6 ADC Input Models
        7. 18.2.2.7 Channel Selection
      3. 18.2.3 EOC and Interrupt Operation
        1. 18.2.3.1 Interrupt Overflow
        2. 18.2.3.2 Continue to Interrupt Mode
        3. 18.2.3.3 Early Interrupt Configuration Mode
      4. 18.2.4 Post-Processing Blocks
        1. 18.2.4.1 PPB Limit Detection
        2. 18.2.4.2 PPB Oversampling
          1. 18.2.4.2.1 Accumulation and Average Functions
      5. 18.2.5 ADC Results
        1. 18.2.5.1 FIFO Operation
      6. 18.2.6 Power-Up Sequence
      7. 18.2.7 ADC Timings
        1. 18.2.7.1 ADC Timing Diagrams
    3. 18.3 ADC_LITE_REGS Registers
    4. 18.4 ADC_LITE_RESULT_REGS Registers
  21. 19VREF
    1. 19.1 VREF Overview
    2. 19.2 VREF Operation
      1. 19.2.1 Internal Reference Generation
      2. 19.2.2 External Reference Input
      3. 19.2.3 Analog Peripheral Interface
      4. 19.2.4 Sample and Hold Mode
    3. 19.3 VREF Registers
  22. 20COMP
    1. 20.1 Comparator Overview
    2. 20.2 Comparator Operation
      1. 20.2.1  Comparator Configuration
      2. 20.2.2  Comparator Channels Selection
      3. 20.2.3  Comparator Output
      4. 20.2.4  Output Filter
      5. 20.2.5  Sampled Output Mode
      6. 20.2.6  Blanking Mode
      7. 20.2.7  Reference Voltage Generator
      8. 20.2.8  Comparator Hysteresis
      9. 20.2.9  Input SHORT Switch
      10. 20.2.10 Analog Comparison Feature
      11. 20.2.11 Interrupt and Events Support
        1. 20.2.11.1 CPU Interrupt Event Publisher (CPU_INT)
        2. 20.2.11.2 Generic Event Publisher (GEN_EVENT)
        3. 20.2.11.3 Generic Event Subscribers
    3. 20.3 COMP Registers
  23. 21UNICOMM
    1. 21.1 Overview
      1. 21.1.1 Block Diagram
    2. 21.2 Unicomm Architecture
      1. 21.2.1 Serial Peripheral Group (SPG) Configurations
        1. 21.2.1.1 I2C Pairings
      2. 21.2.2 Enables & Resets
    3. 21.3 High-Level Initialization
    4. 21.4 UNICOMM/SPGSS Registers
      1. 21.4.1 UNICOMM Registers
        1. 21.4.1.1 UNICOMM Registers
      2. 21.4.2 SPG Registers
        1. 21.4.2.1 SPGSS Registers
  24. 22UNICOMM UART
    1. 22.1 UART Overview
      1. 22.1.1 Purpose of the Peripheral
      2. 22.1.2 Features
      3. 22.1.3 Functional Block Diagram
    2. 22.2 UART Operation
      1. 22.2.1 Clock Control
      2. 22.2.2 General Architecture and Protocol
        1. 22.2.2.1 Signal Descriptions
        2. 22.2.2.2 Transmit and Receive Logic
        3. 22.2.2.3 Bit Sampling
        4. 22.2.2.4 Baud Rate Generation
        5. 22.2.2.5 Data Transmission
        6. 22.2.2.6 Error and Status
        7. 22.2.2.7 DMA Operation
        8. 22.2.2.8 Internal Loopback Operation
      3. 22.2.3 Additional Protocol and Feature Support
        1. 22.2.3.1  Local Interconnect Network (LIN) Support
          1. 22.2.3.1.1 LIN Commander Transmit
          2. 22.2.3.1.2 LIN Responder Receive
          3. 22.2.3.1.3 LIN Responder Transmission Delay
        2. 22.2.3.2  Flow Control
        3. 22.2.3.3  RS485 Support
        4. 22.2.3.4  FIFO Operation
        5. 22.2.3.5  Idle-Line Multiprocessor
        6. 22.2.3.6  9-Bit UART Mode
        7. 22.2.3.7  DALI Protocol
        8. 22.2.3.8  Manchester Encoding and Decoding
        9. 22.2.3.9  IrDA Encoding and Decoding
        10. 22.2.3.10 ISO7816 Smart Card Support
        11. 22.2.3.11 Address Detection
        12. 22.2.3.12 Glitch Suppression
      4. 22.2.4 Low Power Operation
      5. 22.2.5 Reset Considerations
      6. 22.2.6 UART Initialization
      7. 22.2.7 Interrupt and Events Support
        1. 22.2.7.1 CPU Interrupt Event Publisher (CPU_INT)
        2. 22.2.7.2 DMA Trigger Publisher (DMA_TRIG_RX, DMA_TRIG_TX)
      8. 22.2.8 Emulation Modes
    3. 22.3 UNICOMMUART Registers
  25. 23UNICOMM-I2C
    1. 23.1 UNICOMM-I2C Overview
      1. 23.1.1 Purpose of the Peripheral
      2. 23.1.2 Features
      3. 23.1.3 Functional Block Diagram
      4. 23.1.4 Environment and External Connections
    2. 23.2 UNICOMM Common Infrastructure
    3. 23.3 Peripheral Functional Description
      1. 23.3.1 Clock Control
        1. 23.3.1.1 Clock Select and I2C Speed
        2. 23.3.1.2 Clock Startup
      2. 23.3.2 Signal Descriptions
      3. 23.3.3 General Architecture
        1. 23.3.3.1  I2C Bus Functional Overview
        2. 23.3.3.2  START and STOP Conditions
        3. 23.3.3.3  Dual Address
        4. 23.3.3.4  Address Format
          1. 23.3.3.4.1 Data Format with 7-Bit Address
          2. 23.3.3.4.2 Data Format with 10-Bit Address
        5. 23.3.3.5  Acknowledge
        6. 23.3.3.6  Repeated Start
        7. 23.3.3.7  Clock Stretching
        8. 23.3.3.8  Clock Low Timeout
        9. 23.3.3.9  Burst Mode
        10. 23.3.3.10 Arbitration
        11. 23.3.3.11 Multiple Controller Mode
        12. 23.3.3.12 Glitch Suppression
        13. 23.3.3.13 DMA Operation
        14. 23.3.3.14 FIFO Operation
          1. 23.3.3.14.1 FIFO Status Flags
          2. 23.3.3.14.2 FIFO Levels
          3. 23.3.3.14.3 Clearing FIFO Contents
        15. 23.3.3.15 Suspend Communication
        16. 23.3.3.16 Low Power Operation
        17. 23.3.3.17 SMBUS 3.0 Support
          1. 23.3.3.17.1 Quick Command
          2. 23.3.3.17.2 SMBUS Enhanced Acknowledge Control
          3. 23.3.3.17.3 Clock Low Timeout Detection
          4. 23.3.3.17.4 Clock High Timeout Detection
          5. 23.3.3.17.5 Cumulative Clock Low Extended Timeout
          6. 23.3.3.17.6 Packet Error Checking (PEC)
          7. 23.3.3.17.7 Host Notify Protocol
          8. 23.3.3.17.8 Alert Response Protocol
          9. 23.3.3.17.9 Address Resolution Protocol
      4. 23.3.4 Protocol Descriptions & Initialization
        1. 23.3.4.1 I2C Controller Mode
          1. 23.3.4.1.1 I2C Controller Initialization
          2. 23.3.4.1.2 I2C Controller Status
          3. 23.3.4.1.3 I2C Controller Receive Mode
          4. 23.3.4.1.4 I2C Controller Transmitter Mode
          5. 23.3.4.1.5 Controller Transaction Configurations
        2. 23.3.4.2 I2C Target Mode
          1. 23.3.4.2.1 I2C Target Initialization
          2. 23.3.4.2.2 I2C Target Status
          3. 23.3.4.2.3 I2C Target Receiver Mode
          4. 23.3.4.2.4 I2C Target Transmitter Mode
      5. 23.3.5 Reset Considerations
      6. 23.3.6 Initialization
      7. 23.3.7 Interrupt and Events Support
        1. 23.3.7.1 CPU Interrupt Event Publisher (CPU_INT)
        2. 23.3.7.2 DMA Trigger Publisher (DMA_TRIG_RX, DMA_TRIG_TX)
      8. 23.3.8 Emulation Modes
    4. 23.4 UNICOMM I2C Registers
      1. 23.4.1 UNICOMMI2CC Registers
      2. 23.4.2 UNICOMMI2CT Registers
  26. 24UNICOMM-SPI
    1. 24.1 UNICOMM-SPI Overview
      1. 24.1.1 Purpose of the Peripheral
      2. 24.1.2 Features
      3. 24.1.3 Functional Block Diagram
      4. 24.1.4 External Connections and Signal Descriptions
    2. 24.2 SPI Operation
      1. 24.2.1  Clock Frequency Support
        1. 24.2.1.1 SPI Clock Generation
      2. 24.2.2  General Architecture
        1. 24.2.2.1 Chip Select and Command Handling
          1. 24.2.2.1.1 Chip Select Control
        2. 24.2.2.2 Command Data Control
        3. 24.2.2.3 Data Format
        4. 24.2.2.4 Delayed data sampling
        5. 24.2.2.5 DMA Operation
      3. 24.2.3  FIFO Operation
        1. 24.2.3.1 FIFO Size
        2. 24.2.3.2 FIFO Status bits
          1. 24.2.3.2.1 RIS.RX based on FIFO threshold settings
          2. 24.2.3.2.2 RIS.TX based on FIFO threshold settings
        3. 24.2.3.3 Clearing FIFO contents
        4. 24.2.3.4 Hardware monitors empty, full and overflow conditions
      4. 24.2.4  Suspend communication
        1. 24.2.4.1 SPI IDLE State Requirements
      5. 24.2.5  Internal Loopback Operation
      6. 24.2.6  Repeat Transfer mode
      7. 24.2.7  Receive Timeout
      8. 24.2.8  Line Timeout
      9. 24.2.9  Protocol Descriptions
        1. 24.2.9.1 Motorola SPI Frame Format
        2. 24.2.9.2 Texas Instruments Synchronous Serial Frame Format
      10. 24.2.10 Status Flags
      11. 24.2.11 Module configuration
      12. 24.2.12 Reset Considerations
      13. 24.2.13 Initialization
      14. 24.2.14 Interrupt and Events Support
        1. 24.2.14.1 CPU Interrupt Event Publisher (CPU_INT)
        2. 24.2.14.2 DMA Trigger Publisher (DMA_TRIG_RX, DMA_TRIG_TX)
      15. 24.2.15 Emulation Modes
        1. 24.2.15.1 Graceful Halt
    3. 24.3 UNICOMMSPI Registers
  27. 25QSPI
    1. 25.1 QSPI Overview
      1. 25.1.1 Purpose of the Peripheral
      2. 25.1.2 Features
      3. 25.1.3 Functional Block Diagram
      4. 25.1.4 External Connections and Signal Descriptions
    2. 25.2 QSPI Operation
      1. 25.2.1 Clock Control
      2. 25.2.2 General Architecture
        1. 25.2.2.1 Chip Select Control
        2. 25.2.2.2 Data Format
        3. 25.2.2.3 Delayed data sampling
        4. 25.2.2.4 Loopback mode
        5. 25.2.2.5 FIFO Operation
        6. 25.2.2.6 DMA Operation
        7. 25.2.2.7 Lower Power Mode
      3. 25.2.3 Reset Considerations
      4. 25.2.4 Initialization
      5. 25.2.5 QSPI Controller Description
        1. 25.2.5.1 Configuration Frame Access
        2. 25.2.5.2 Status Frame Access
        3. 25.2.5.3 Data packing and unpacking
        4. 25.2.5.4 Data Frame Access
          1. 25.2.5.4.1 SSS mode (QSPIFORMAT = 1000)
          2. 25.2.5.4.2 SSD mode (QSPIFORMAT = 1001)
          3. 25.2.5.4.3 SDD mode (QSPIFORMAT = 1010)
          4. 25.2.5.4.4 SSQ mode (QSPIFORMAT = 1011)
          5. 25.2.5.4.5 SQQ mode (QSPIFORMAT = 1100)
          6. 25.2.5.4.6 QQQ mode (QSPIFORMAT = 1101)
      6. 25.2.6 Interrupt and Events Support
        1. 25.2.6.1 CPU Interrupt Event Publisher (CPU_INT)
        2. 25.2.6.2 DMA Trigger Publisher (DMA_TRIG_RX, DMA_TRIG_TX)
      7. 25.2.7 Emulation Modes
    3. 25.3 QSPI Registers
  28. 26CAN-FD
    1. 26.1 MCAN Overview
      1. 26.1.1 MCAN Features
    2. 26.2 MCAN Environment
    3. 26.3 CAN Network Basics
    4. 26.4 MCAN Functional Description
      1. 26.4.1  Clock Setup
      2. 26.4.2  Module Clocking Requirements
      3. 26.4.3  Interrupt Requests
      4. 26.4.4  Operating Modes
        1. 26.4.4.1 Normal Operation
        2. 26.4.4.2 CAN Classic
        3. 26.4.4.3 CAN FD Operation
      5. 26.4.5  Software Initialization
      6. 26.4.6  Transmitter Delay Compensation
        1. 26.4.6.1 Description
        2. 26.4.6.2 Transmitter Delay Compensation Measurement
      7. 26.4.7  Restricted Operation Mode
      8. 26.4.8  Bus Monitoring Mode
      9. 26.4.9  Disabled Automatic Retransmission (DAR) Mode
        1. 26.4.9.1 Frame Transmission in DAR Mode
      10. 26.4.10 Clock Stop Mode
        1. 26.4.10.1 Suspend Mode
        2. 26.4.10.2 Wakeup Request
      11. 26.4.11 Test Modes
        1. 26.4.11.1 External Loop Back Mode
        2. 26.4.11.2 Internal Loop Back Mode
      12. 26.4.12 Timestamp Generation
        1. 26.4.12.1 External Timestamp Counter
      13. 26.4.13 Timeout Counter
      14. 26.4.14 Safety
        1. 26.4.14.1 MCAN ECC Wrapper
        2. 26.4.14.2 MCAN ECC Aggregator
          1. 26.4.14.2.1 MCAN ECC Aggregator Overview
          2. 26.4.14.2.2 MCAN ECC Aggregator Registers
        3. 26.4.14.3 Reads to ECC Control and Status Registers
        4. 26.4.14.4 ECC Interrupts
      15. 26.4.15 Tx Handling
        1. 26.4.15.1 Transmit Pause
        2. 26.4.15.2 Dedicated Tx Buffers
        3. 26.4.15.3 Tx FIFO
        4. 26.4.15.4 Tx Queue
        5. 26.4.15.5 Mixed Dedicated Tx Buffers/Tx FIFO
        6. 26.4.15.6 Mixed Dedicated Tx Buffers/Tx Queue
        7. 26.4.15.7 Transmit Cancellation
        8. 26.4.15.8 Tx Event Handling
        9. 26.4.15.9 FIFO Acknowledge Handling
      16. 26.4.16 Rx Handling
        1. 26.4.16.1 Acceptance Filtering
          1. 26.4.16.1.1 Range Filter
          2. 26.4.16.1.2 Filter for Specific IDs
          3. 26.4.16.1.3 Classic Bit Mask Filter
          4. 26.4.16.1.4 Standard Message ID Filtering
          5. 26.4.16.1.5 Extended Message ID Filtering
      17. 26.4.17 Rx FIFOs
        1. 26.4.17.1 Rx FIFO Blocking Mode
        2. 26.4.17.2 Rx FIFO Overwrite Mode
      18. 26.4.18 Dedicated Rx Buffers
        1. 26.4.18.1 Rx Buffer Handling
      19. 26.4.19 Message RAM
        1. 26.4.19.1 Message RAM Configuration
        2. 26.4.19.2 Rx Buffer and FIFO Element
        3. 26.4.19.3 Tx Buffer Element
        4. 26.4.19.4 Tx Event FIFO Element
        5. 26.4.19.5 Standard Message ID Filter Element
        6. 26.4.19.6 Extended Message ID Filter Element
    5. 26.5 MCAN Integration
    6. 26.6 Interrupt and Event Support
      1. 26.6.1 CPU Interrupt Event Publisher (CPU_INT)
    7. 26.7 MCAN Registers
  29. 27I2S/TDM
    1. 27.1 I2S/TDM Introduction
      1. 27.1.1 I2S/TDM features
    2. 27.2 I2S/TDM Operation
      1. 27.2.1  Functional Block Diagram
      2. 27.2.2  Modes of Operation
        1. 27.2.2.1 Controller Mode
        2. 27.2.2.2 Target Mode
      3. 27.2.3  Clock and Timing Control
      4. 27.2.4  Frame Synchronization
        1. 27.2.4.1 Frame and Word Length
        2. 27.2.4.2 Polarity
        3. 27.2.4.3 Data Delay (Offset)
      5. 27.2.5  Slot Mapping and Configuration
        1.       Data Direction Configuration
        2. 27.2.5.1 Channel Mapping in Memory
      6. 27.2.6  Serial Frame Format Examples
        1. 27.2.6.1 I2S Format
        2. 27.2.6.2 Right Justified Format
        3. 27.2.6.3 Left Justified Format
        4. 27.2.6.4 DSP Format
        5. 27.2.6.5 PCM Long Frame Format
        6. 27.2.6.6 TDM Classic Format
      7. 27.2.7  Initialization
      8. 27.2.8  Disabling I2S
      9. 27.2.9  Interrupts and Events Support
        1. 27.2.9.1 CPU Interrupt Event Publisher (CPU_INT)
        2. 27.2.9.2 DMA Trigger Publisher (DMA_TRIG_RX, DMA_TRIG_TX)
      10. 27.2.10 Emulation Modes
    3. 27.3 I2S Registers
  30. 28Timers (TIMx)
    1. 28.1 TIMx Overview
      1. 28.1.1 TIMG Overview
        1. 28.1.1.1 TIMG Features
        2. 28.1.1.2 Functional Block Diagram
      2. 28.1.2 TIMA Overview
        1. 28.1.2.1 TIMA Features
        2. 28.1.2.2 Functional Block Diagram
      3. 28.1.3 TIMx Instance Configuration
    2. 28.2 TIMx Operation
      1. 28.2.1  Timer Counter
        1. 28.2.1.1 Clock Source Select and Prescaler
          1. 28.2.1.1.1 Internal Clock and Prescaler
          2. 28.2.1.1.2 External Signal Trigger
        2. 28.2.1.2 Repeat Counter (TIMA only)
      2. 28.2.2  Counting Mode Control
        1. 28.2.2.1 One-shot and Periodic Modes
        2. 28.2.2.2 Down Counting Mode
        3. 28.2.2.3 Up/Down Counting Mode
        4. 28.2.2.4 Up Counting Mode
        5. 28.2.2.5 Phase Load (TIMA only)
      3. 28.2.3  Capture/Compare Module
        1. 28.2.3.1 Capture Mode
          1. 28.2.3.1.1 Input Selection, Counter Conditions, and Inversion
            1. 28.2.3.1.1.1 CCP Input Edge Synchronization
            2. 28.2.3.1.1.2 CCP Input Pulse Conditions
            3. 28.2.3.1.1.3 Counter Control Operation
            4. 28.2.3.1.1.4 CCP Input Filtering
            5. 28.2.3.1.1.5 Input Selection
          2. 28.2.3.1.2 Use Cases
            1. 28.2.3.1.2.1 Edge Time Capture
            2. 28.2.3.1.2.2 Period Capture
            3. 28.2.3.1.2.3 Pulse Width Capture
            4. 28.2.3.1.2.4 Combined Pulse Width and Period Time
          3. 28.2.3.1.3 QEI Mode (TIMG with QEI support only)
            1. 28.2.3.1.3.1 QEI With 2-Signal
            2. 28.2.3.1.3.2 QEI With Index Input
            3. 28.2.3.1.3.3 QEI Error Detection
          4. 28.2.3.1.4 Hall Input Mode (TIMG with QEI support only)
        2. 28.2.3.2 Compare Mode
          1. 28.2.3.2.1 Edge Count
      4. 28.2.4  Shadow Load and Shadow Compare
        1. 28.2.4.1 Shadow Load (TIMG4-7, TIMA only)
        2. 28.2.4.2 Shadow Compare (TIMG4-7, TIMG12-13, TIMA only)
      5. 28.2.5  Output Generator
        1. 28.2.5.1 Configuration
        2. 28.2.5.2 Use Cases
          1. 28.2.5.2.1 Edge-Aligned PWM
          2. 28.2.5.2.2 Center-Aligned PWM
          3. 28.2.5.2.3 Asymmetric PWM (TIMA only)
          4. 28.2.5.2.4 Complementary PWM With Deadband Insertion (TIMA only)
        3. 28.2.5.3 Forced Output
      6. 28.2.6  Fault Handler (TIMA only)
        1. 28.2.6.1 Fault Input Conditioning
        2. 28.2.6.2 Fault Input Sources
        3. 28.2.6.3 Counter Behavior With Fault Conditions
        4. 28.2.6.4 Output Behavior With Fault Conditions
      7. 28.2.7  Synchronization With Cross Trigger
        1. 28.2.7.1 Main Timer Cross Trigger Configuration
        2. 28.2.7.2 Secondary Timer Cross Trigger Configuration
      8. 28.2.8  Low Power Operation
      9. 28.2.9  Interrupt and Event Support
        1. 28.2.9.1 CPU Interrupt Event Publisher (CPU_INT)
        2. 28.2.9.2 Generic Event Publisher and Subscriber (GEN_EVENT0 and GEN_EVENT1)
        3. 28.2.9.3 Generic Subscriber Event Example (COMP to TIMx)
      10. 28.2.10 Debug Handler (TIMA Only)
    3. 28.3 TIMx Registers
  31. 29Low Frequency Subsystem (LFSS)
    1. 29.1  Overview
    2. 29.2  Clock System
    3. 29.3  LFSS Reset Using VBAT
    4. 29.4  Power Domains and Supply Detection
      1. 29.4.1 Startup When VBAT Powers on First
      2. 29.4.2 Startup when VDD powers on first
      3. 29.4.3 Behavior When VDD is Lost
      4. 29.4.4 Behavior when VBAT is lost
      5. 29.4.5 Behavior when the device goes into SHUTDOWN mode
      6. 29.4.6 Supercapacitor Charging Circuit
    5. 29.5  Real Time Counter (RTC_x)
    6. 29.6  Independent Watchdog Timer (IWDT)
    7. 29.7  Tamper Input and Output
      1. 29.7.1 IOMUX Mode
      2. 29.7.2 Tamper Mode
        1. 29.7.2.1 Tamper Event Detection
        2. 29.7.2.2 Timestamp Event Output
        3. 29.7.2.3 Heartbeat Generator
        4. 29.7.2.4 RTC Clock Output
    8. 29.8  Scratchpad Memory
    9. 29.9  Lock Function of RTC, TIO, and IWDT
    10. 29.10 LFSS Registers
  32. 30RTC
    1. 30.1 Overview
      1. 30.1.1 RTC Instances
    2. 30.2 Basic Operation
    3. 30.3 Configuration
      1. 30.3.1  Clocking
      2. 30.3.2  Reading and Writing to RTC Peripheral Registers
      3. 30.3.3  Binary vs. BCD
      4. 30.3.4  Leap Year Handling
      5. 30.3.5  Calendar Alarm Configuration
      6. 30.3.6  Interval Alarm Configuration
      7. 30.3.7  Periodic Alarm Configuration
      8. 30.3.8  Calibration
        1. 30.3.8.1 Crystal Offset Error
          1. 30.3.8.1.1 Offset Error Correction Mechanism
        2. 30.3.8.2 Crystal Temperature Error
          1. 30.3.8.2.1 Temperature Drift Correction Mechanism
      9. 30.3.9  RTC Prescaler Extension
      10. 30.3.10 RTC Timestamp Capture
      11. 30.3.11 RTC Events
        1. 30.3.11.1 CPU Interrupt Event Publisher (CPU_INT)
        2. 30.3.11.2 Generic Event Publisher (GEN_EVENT)
    4. 30.4 RTC Registers
  33. 31IWDT
    1. 31.1 865
    2. 31.2 IWDT Clock Configuration
    3. 31.3 IWDT Period Selection
    4. 31.4 Debug Behavior of the IWDT
    5. 31.5 IWDT Registers
  34. 32Window Watchdog Timer (WWDT)
    1. 32.1 WWDT Overview
      1. 32.1.1 Watchdog Mode
      2. 32.1.2 Interval Timer Mode
    2. 32.2 WWDT Operation
      1. 32.2.1 Mode Selection
      2. 32.2.2 Clock Configuration
      3. 32.2.3 Low-Power Mode Behavior
      4. 32.2.4 Debug Behavior
      5. 32.2.5 WWDT Events
        1. 32.2.5.1 CPU Interrupt Event Publisher (CPU_INT)
    3. 32.3 WWDT Registers
  35. 33Debug
    1. 33.1 DEBUGSS Overview
      1. 33.1.1 Debug Interconnect
      2. 33.1.2 Physical Interface
      3. 33.1.3 Debug Access Ports
    2. 33.2 DEBUGSS Operation
      1. 33.2.1 Debug Features
        1. 33.2.1.1 Processor Debug
          1. 33.2.1.1.1 Breakpoint Unit (BPU)
          2. 33.2.1.1.2 Data Watchpoint and Trace Unit (DWT)
          3. 33.2.1.1.3 Processor Trace (MTB)
        2. 33.2.1.2 Peripheral Debug
      2. 33.2.2 Behavior in Low Power Modes
      3. 33.2.3 Restricting Debug Access
      4. 33.2.4 Mailbox (DSSM)
        1. 33.2.4.1 DSSM Events
          1. 33.2.4.1.1 CPU Interrupt Event (CPU_INT)
        2. 33.2.4.2 Reference
    3. 33.3 DEBUGSS Registers
  36. 34Revision History

2.6.3 Asynchronous Fast Clock Requests

Peripherals are configured to asynchronously assert a hardware request to the SYSCTL for a fast clock source when the device is operating in STANDBY mode. This mechanism for applications where the ULPCLK tree is sourced from LFCLK (at 32kHz), but a faster SYSOSC (at 4 MHz) is temporarily needed to quickly handle a peripheral event (for example, a timer IRQ or GPIO IRQ) or peripheral activity (such as serial communication or GPIO toggle validation thriugh the glitch filter).

Asynchronous fast clock requests are also useful for scenarios where the device is running in STANDBY1 mode. In STANDBY1 (when STOPCLKSTBY is set), the ULPCLK and LFCLK are disabled to all peripherals except for a few TIMG8_x, leaving TIMG8_x and the RTC as the only clocked peripherals. To wake up the device from this state where the bus clock (ULPCLK) is disabled, a TIMG8_x or RTC interrupt request forces an asynchronous fast clock request to wake the device to RUN mode. Other peripherals can also wake the device from this state if support for detecting an asynchronous event (for example GPIO, comparator, and serial interfaces) is described.

Asynchronous fast clock requests temporarily provide peripherals with bus clock ( ULPCLK), sourced from the SYSOSC, for the duration of the request. MFCLK, if enabled for use, is also enabled during the asynchronous request.

Asynchronous Fast Clock Behavior

When configured, SYSCTL responds to a peripheral fast clock request in the following way:

  1. If the device is currently in STANDBY mode, the low power state is temporarily suspended to support running the bus clock (ULPCLK) at the SYSOSC in 4 MHz mode, SYSOSC start-up in 4 MHz will be forced in this state.
  2. Device in STANDBY mode and temporarily operates in STOP mode.
  3. The MCLK/ULPCLK tree is forced to be sourced from SYSOSC at the base frequency; if the device is in RUN mode then the CPUCLK is also switches to the SYSOSC rate (the CPUCLK is always derived from MCLK)
  4. If the MFCLK is configured to be used, MFCLK is activated

After the configuration above is applied, values are held for the duration of time that the asynchronous request remains asserted plus approximately 1µs after the request is removed. The system then returns to the configuration which existed before the fast clock request, provided the CPU did not change the configuration during the request.

Asynchronous fast clock requests are ignored and results in no effect on the device configuration if any of the following are true:

  • MCLK is already sourced from SYSOSC at base frequency
  • Asynchronous fast clock requests are globally blocked by setting the BLOCKASYNCALL bit in the SYSOSCCFG register in SYSCTL

Peripheral Support

The RTC, TIMG8_x, GPIO, I2C, and UART peripherals all provide support for generating an asynchronous fast clock request. The purpose, request source, and configuration requirements for these peripherals are given in Table 2-14.

Table 2-14 Peripheral Support for Asynchronous Fast Clock Requests
Peripheral Purpose Request Source Configuration
RTC (if present) Fast CPU wake from RTC event RTC IRQ to CPU An RTC IRQ event always generates an asynchronous fast clock request when the device is in STANDBY1 mode; this is needed to wake the device as the main ULPCLK is disabled to reduce power consumption. The RTC can also be configured to generate an asynchronous fast clock request in any operating mode by clearing the BLOCKASYNC bit in the RTC CLKCFG register; this provides the lowest latency RTC event response.
TIMG8_x Fast CPU wake from TIMGx event TIMGx, IRQ to CPU An IRQ event from TIMG8_x generates an asynchronous fast clock request when the device is in STANDBY1 mode and the corresponding IMASK interrupt is set in the TIMG8_x registers. This is needed to wake the device as the ULPCLK is disabled to reduce power consumption.
GPIO Fast CPU wake from GPIO event GPIO activity The GPIO generates an asynchronous fast clock request through the GPIO configuration registers. This is for applications where GPIO wake from STANDBY mode is desired, as the fast clock request results in the GPIO digital glitch filters running at SYSOSC base frequency. In addition to configuring the GPIO registers to request the fast clock, the BLOCKASYNCALL bit must be cleared in the SYSOSCCFG register to allow the request to propagate.
I2C Temporarily use fast clock for bit clock generation I2C activity I2C activity generates an asynchronous fast clock request when the BLOCKASYNC bit is cleared in the CLKCFG register of the respective I2C peripheral.
UART Temporarily use a fast clock for baud rate generation UART activity UART activity generates an asynchronous fast clock request when the BLOCKASYNC bit is cleared in the CLKCFG register of the respective UART peripheral.

Asynchronous Fast Clock Request Logic

The logic for asserting a fast clock request is given in the following figure.

Asynchronous Fast Clock Request Logic Figure 2-10 Asynchronous Fast Clock Request Logic
Note: Not all the devices support RTC or comparator, check the device specific data sheet to determine if these peripherals are present or not.