AN3262

Bootloader command set

Doc ID 17845 Rev 2

13/27

Figure 15.

3.4

memory and the information block (System memory or option byte areas).

application. After sending the ACK byte, the bootloader waits for an address (4 bytes, where

Byte 1 is the address MSB and Byte 4 is the LSB) and a checksum byte. Then it checks the

received address. If the address is valid and the checksum is correct, the bootloader

transmits an ACK byte, otherwise it transmits a NACK byte and aborts the command.

When the address is valid and the checksum is correct, the bootloader waits for the number

of bytes to be transmitted – 1 (N bytes) and for its complemented byte (checksum). If the

checksum is correct, it then transmits the needed data ((N + 1) bytes) to the application,

starting from the received address. If the checksum is not correct, it sends a NACK before

aborting the command.

The host sends bytes to the STM32 as follows:

Bytes 1-2:

0x11+0xEE

Wait for ACK

Bytes 3 to 6:

Start address (Byte 3 is MSB and Byte 6 is LSB)

Byte 7:

Checksum (XOR value of Bytes 3 to 6)

Wait for ACK

Byte 8:

The number of bytes to be read – 1 (0 < N

≤ 95);

Byte 9:

Checksum (XOR value (complement) of Byte 8)