AN3154 datasheet(17/34 Pages) STMICROELECTRONICS

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AN3154

Bootloader command set

3.5

Read Memory command

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

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

areas).

When the bootloader receives the Read Memory command, it starts to verify the contents of

the message:

•

ID of the command is correct or not

•

ReadOutProtection is disabled or enabled

•

Address to be read is valid or not

If the message content is correct it transmits an ACK message otherwise it transmits a

NACK message.

After sending an ACK message, then it transmits the required data to the application ((N +

1) bytes) via (N+1) messages /8 (since each message contains 8 bytes), starting from the

received address.

Figure 12. Read memory command: host side

The host sends messages as follows:

Command message:

Std ID = 0x11, DLC = 0x05, data[0] = 0xXX: MSB of the address... data[3] = 0xYY: LSB of

the address, data[4] = N: number of bytes to be read (where 0 < N

≤255).

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