AN3154 datasheet(23/34 Pages) STMICROELECTRONICS

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AN3154

Bootloader command set

After each received message, the device will send an ACK if the content of the command is

correct else a NACK. However, as described in Figure 17, after receiving all the 'data

messages' (N/8 messages) and temporarily write the data to RAM, if none of the messages

content is corrupted, the bootloader will write the N bytes at the requested address (Flash

memory, RAM or option byte), then if the write operation is successfully completed, device

will send an ACK message to the host.

In other terms, after sending the N/8 messages, host will receive two successive ACK; the

first will be sent by the device if the last message of the N/8 is correctly received, and the

second ACK will be sent after writing correctly the N/8 message at the requested address

3.8

Erase Memory command

The Erase Memory command allows the host to erase Flash memory pages. When the

bootloader receives the Erase Memory command and ROP is disabled, it transmits the ACK

message to the host. After the transmission of the ACK message, the bootloader checks if

data[0] is equal to 0xFF, if it is the case a global memory erase operation will be started and

when finished it sends ACK message. Otherwise (data[0] is different from 0xFF), the

bootloader will start the memory page(s) erase as defined by the host, and after each page

erase it sends ACK or NACK message.

Erase Memory command specifications:

The bootloader receives one message that contains N, the number of pages to be

erased – 1.

N = 255 is reserved for global erase requests. For 0

≤N ≤254, N + 1 pages are erased.

The bootloader receives (N + 1) bytes, each byte containing a page number

Note:

No error is returned when performing erase operations on write protected sectors.

AN3154 Datenblatt(PDF) 23 Page - STMicroelectronics