SLUUDI6 December   2025 MSPM33C321A

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Overview of BSL Features
    2. 1.2 Terminology
    3. 1.3 Additional resources
  5. 2BSL Architecture
    1. 2.1 Design
      1. 2.1.1 Timeout Feature
        1. 2.1.1.1 Interface Autodetection
        2. 2.1.1.2 Command Reception
    2. 2.2 BSL Invocation
      1. 2.2.1 Application Request
      2. 2.2.2 GPIO Based Invocation
      3. 2.2.3 Debug Mailbox Command
      4. 2.2.4 Other BSL Invocation Methods
        1. 2.2.4.1 Pre-Boot Application Verification
        2. 2.2.4.2 Blank Device Handling
    3. 2.3 Memory
      1. 2.3.1 SRAM Memory Usage
    4. 2.4 BSL Non-Main Configuration
      1. 2.4.1  BSL Configuration ID
      2. 2.4.2  BSL Interface Pins (BLINTERFACE_PINS)
      3. 2.4.3  BSL Invoke Pin Configuration (BSLPIN_INVOKE)
      4. 2.4.4  Memory Readout Configuration
      5. 2.4.5  BSL Password
      6. 2.4.6  Application Revision Pointer
      7. 2.4.7  Security Alert Level
      8. 2.4.8  UART Baud Rate
      9. 2.4.9  I2C Slave Address
      10. 2.4.10 Configuration CRC
    5. 2.5 Changing BSL Configuration
      1. 2.5.1 Reference
      2. 2.5.2 Using SysConfig and Code Composer Studio (CCS)
      3. 2.5.3 Using Debug Interface
  6. 3Bootloader Protocol
    1. 3.1 Packet Format
    2. 3.2 BSL Protocol
      1. 3.2.1 BSL Acknowledgment
      2. 3.2.2 Peripheral Configuration
        1. 3.2.2.1 UART
        2. 3.2.2.2 I2C
        3. 3.2.2.3 CRC
    3. 3.3 Bootloader Core Commands
      1. 3.3.1  Connection
      2. 3.3.2  Get Device Info
      3. 3.3.3  Unlock Bootloader
      4. 3.3.4  Program Data
      5. 3.3.5  Program Data Fast
      6. 3.3.6  Readback Data
      7. 3.3.7  Flash Range Erase
      8. 3.3.8  Mass Erase
      9. 3.3.9  Factory Reset
      10. 3.3.10 Standalone Verification
      11. 3.3.11 Start Application
      12. 3.3.12 Change Baud Rate
    4. 3.4 Bootloader Core Response
      1. 3.4.1 BSL Core Message
      2. 3.4.2 Detailed Error
      3. 3.4.3 Memory Readback
      4. 3.4.4 Device Info
      5. 3.4.5 Standalone Verification
    5. 3.5 Bootloader Security
      1. 3.5.1 Password Protected Commands
        1. 3.5.1.1 Security Alert
      2. 3.5.2 BSL Entry
  7. 4Sample Program Flow with Bootloader
  8. 5Revision History

3.2.1 BSL Acknowledgment

The peripheral interface section of the BSL software parses the wrapper section of the BSL data packet. If there are errors with the data transmission, an error message is sent immediately. An ACK is sent after all data has been successfully received and does not mean that the command has been correctly executed (or even that the command was valid) but, rather, that the data packet was formatted correctly and passed on to the BSL core software for interpretation.

The BSL protocol dictates that every BSL data packet sent is responded to with a single byte acknowledgment in addition to any BSL data packets that are sent. Table lists the acknowledgment responses from the BSL. If an acknowledgment byte other than ACK is sent, the BSL does not send any BSL data packets. The host programmer must check the acknowledgment error and retry transmission.

DataMeaning
0x00BSL_ACK (Packet received successfully)
0x51BSL_ERROR_HEADER_INCORRECT
0x52BSL_ERROR_CHECKSUM_INCORRECT
0x53BSL_ERROR_PACKET_SIZE_ZERO
0x54BSL_ERROR_PACKET_SIZE_TOO_BIG
0x55BSL_ERROR_UNKNOWN_ERROR
0x56BSL_ERROR_UNKNOWN_BAUD_RATE