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AN3155

Bootloader command set

3

Bootloader command set

The supported commands are listed in Table 2 below. Each command is further described in

this section.

Communication safety

All communications from the programming tool (PC) to the device are verified by:

1.

checksum: received blocks of data bytes are XORed. A byte containing the computed

XOR of all previous bytes is added to the end of each communication (checksum byte).

By XORing all received bytes, data + checksum, the result at the end of the packet

must be 0x00

2.

for each command the host sends a byte and its complement (XOR = 0x00)

3.

UART: parity check active (even parity)

Table 2. USART bootloader commands

1. If a denied command is received or an error occurs during the command execution, the bootloader sends

NACK byte and goes back to command checking.

Command code

Command description

2. Read protection – When the RDP (read protection) option is active, only this limited subset of commands is

available. All other commands are NACKed and have no effect on the device. Once the RDP has been

removed, the other commands become active.

0x00

Gets the version and the allowed commands supported

by the current version of the bootloader

Get Version & Read

Protection Status(2)

0x01

Gets the bootloader version and the Read Protection

status of the Flash memory

Get ID(2)

0x02

Gets the chip ID

3. Refer to STM32 product datasheets and to the “STM32 microcontroller system memory boot mode”

application note (AN2606) to know which memory areas are valid for these commands.

0x11

Reads up to 256 bytes of memory starting from an

address specified by the application

Go(3)

0x21

Jumps to user application code located in the internal

Flash memory or in SRAM

Write Memory(3)

0x31

Writes up to 256 bytes to the RAM or Flash memory

starting from an address specified by the application

Erase(3)(4)

4. Erase (x043) and Extended Erase (0x44) are exclusive. A device may support either the Erase command

or the Extended Erase command but not both.

0x43

Erases from one to all the Flash memory pages

Extended Erase(3)(4)

0x44

Erases from one to all the Flash memory pages using

two byte addressing mode (available only for v3.0 usart

bootloader versions and above).

Write Protect

0x63

Enables the write protection for some sectors

Write Unprotect

0x73

Disables the write protection for all Flash memory sectors

Readout Protect

0x82

Enables the read protection

Readout Unprotect(2)

0x92

Disables the read protection