AN3155 datasheet(13/37 Pages) STMICROELECTRONICS

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AN3155

Bootloader command set

Figure 7. Get ID command: device side

1. GID = Get ID.

3.4

Read Memory command

The Read Memory command is used to read data from any valid memory address (see

note) in RAM, Flash memory and the information block (System memory or option byte

areas).

Note:

Refer to STM32 product datasheets and to the “STM32 microcontroller system memory

boot mode” application note (AN2606) for more details about the valid memory addresses

for the device you are using.

When the bootloader receives the Read Memory command, it transmits the ACK byte to the

application. After the transmission of the ACK byte, the bootloader waits for an address (4

bytes, 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

AN3155 Datasheet(PDF) 13 Page - STMicroelectronics