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Host Sends | Command Code | Bootloader Responds | Notes |
---|---|---|---|
BL_GET_VER | 0x51 | Bootloader version number (1 byte) | Used to read the bootloader version from the MCU |
BL_GET_HELP | 0x52 | All supported command codes (1 byte per supported command) | Used to retrieve all the commands that are supported by the bootloader |
BL_GET_CID | 0x53 | Chip identification number (2 bytes) | Used to get the MCU chip identification number |
BL_GO_TO_ADDR | 0x54 | Success or error code (1 byte) | Used to jump bootloader to specified address |
BL_ERASE_FLASH | 0x55 | Success or error code (1 byte) | Used to mass-erase or sector-erase the user Flash |
BL_READ_MEM | 0x56 | Memory contents of length asked by the host | Used to read data from different memories of the MCU |
BL_WRITE_MEM | 0x57 | Success or error code (1 byte) | Used to write data into different memories of the MCU |
BL_GET_RDP_LEVEL | 0x58 | Flash Read Protection (RDP) level (1 byte) | Used to read the Flash Read Protection (RDP) level |
BL_SET_RDP_LEVEL | 0x59 | Success or error code (1 byte) | Used to set the Flash Read Protection (RDP) level |
BL_ENABLE_WRP | 0x5A | Success or error code (1 byte) | Used to enable the Write Protection (WRP) for the selected sectors of the user Flash memory |
BL_DISABLE_WRP | 0x5B | Success or error code (1 byte) | Used to disable the Write Protection (WRP) for all the sectors of the user Flash (i.e., Restores the default protection state) |
BL_GET_WRP_STATUS | 0x5C | All sectors' Write Protection (WRP) status | Used to read the Write Protection (WRP) status of all the sectors of the user Flash memory |
BL_READ_OTP | 0x5D | OTP contents | Used to read the OTP contents |
BL_GO_TO_ADDR: When entering the target address to the host application, make sure to account for the T-bit setting. For example, If the address of the user application's reset handler is 0x08008229, then enter 0x08008228. Please see the bootloader source code for more details.
Upon reset, the MCU will go through the initialization process and then will hang at some point (e.g., USART receive function) ready to receive commands from the host.
Upon receiving a command from the host, the bootloader performs CRC check. It ACKs if the CRC check has succeeded, NACKs otherwise.
After ACKing, the bootloader sends its response to the host.
For every bootloader command
First byte - Length to follow
The second byte - Command code sent by the host to the bootloader
The last four bytes - CRC to check the integrity of the bytes received from the host.
Used to read the bootloader version from the MCU
Total length (in bytes) of the packet: 6
Length to follow: 5
Command code: 0x51
Used to retrieve all the commands that are supported by the bootloader
Total length (in bytes) of the packet: 6
Length to follow: 5
Command code: 0x52
Used to read the MCU chip identification number
Total length (in bytes) of the packet: 6
Length to follow: 5
Command code: 0x53
Used to jump the bootloader to a specified address
Total length (in bytes) of the packet: 10
Length to follow: 9
Command code: 0x54
Base memory address: 4-byte base memory address to jump to (LE: Little Endian)
Used to mass-erase (all sectors) or sector-erase the user Flash
Total length (in bytes) of the packet: 8
Length to follow: 7
Command code: 0x55
Used to read data from different memories (e.g., Flash, SRAM, etc.) of the MCU
Total length (in bytes) of the packet: 11
Length to follow: 10
Command code: 0x56
Base memory address: 4-byte base memory address from which the reading will take place (LE: Little Endian)
Length: The number of bytes to read (Max: 255 bytes)
Used to write data into different memories (e.g., Flash, SRAM, etc.) of the MCU
e.g., Programming binary into the Flash memory
Total length (in bytes) of the packet: 11+n
Length to follow: 10+n
Command code: 0x57
Base memory address: 4-byte base memory address from which the writing will take place (LE: Little Endian)
Payload length: The number of bytes to write (Max: 255 bytes)
Payload: Data to write
Used to read the Flash Read Protection (RDP) level
Total length (in bytes) of the packet: 6
Length to follow: 5
Command code: 0x58
Used to set the Flash Read Protection (RDP) level
Total length (in bytes) of the packet: 7
Length to follow: 6
Command code: 0x59
Read protect level:
0: Level 0, read protection not active
1: Level 1, read protection of memories active
2: Level 2, chip read protection active
Used to enable the Write Protection (WRP) for the selected sectors of the user Flash memory
Total length (in bytes) of the packet: 8
Length to follow: 7
Command code: 0x5A
Sector not write protect (Each bit represents the sector number; e.g., 0th bit is sector 0)
0: Write protection active on selected sector
1: Write protection inactive on selected sector
Used to disable the Write Protection (WRP) for all the sectors of the user Flash (i.e., Restores the default protection state)
Total length (in bytes) of the packet: 6
Length to follow: 5
Command code: 0x5B
Used to read the Write Protection (WRP) status of all the sectors of the user Flash memory
Total length (in bytes) of the packet: 6
Length to follow: 5
Command code: 0x5C