AN3155 datasheet(24/37 Pages) STMICROELECTRONICS

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Bootloader command set

AN3155

24/37

DocID17066 Rev 6

3.8

Extended Erase Memory command

The Extended Erase Memory command allows the host to erase Flash memory pages using

two bytes addressing mode. When the bootloader receives the Extended Erase Memory

command, it transmits the ACK byte to the host. After the transmission of the ACK byte, the

bootloader receives two bytes (number of pages to be erased), the Flash memory page

codes (each one coded on two bytes, MSB first) and a checksum byte (XOR of the sent

bytes); if the checksum is correct, the bootloader erases the memory and sends an ACK

byte to the host. Otherwise it sends a NACK byte to the host and the command is aborted.

Extended Erase Memory command specifications:

The bootloader receives one half-word (two bytes) that contain N, the number of pages

to be erased:

For N = 0xFFFY (where Y is from 0 to F) special erase is performed:

- 0xFFFF for global mass erase

- 0xFFFE for bank 1 mass erase

- 0xFFFD for bank 2 mass erase

- Codes from 0xFFFC to 0xFFF0 are reserved

For other values where 0

≤ N < maximum number of pages: N + 1 pages are

erased.

The bootloader receives:

In the case of a special erase, one byte: checksum of the previous bytes:

- 0x00 for 0xFFFF

- 0x01 for 0xFFFE

- 0x02 for 0xFFFD

In the case of N+1 page erase, the bootloader receives (2 x (N + 1)) bytes, each

half-word containing a page number (coded on two bytes, MSB first). Then all

previous byte checksums (in one byte).

Note:

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

The maximum number of pages is relative to the product and thus should be respected.

Byte 4: 0x00 (in case of global erase) or ((N + 1 bytes (page numbers) and then checksum

XOR (N, N+1 bytes))

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