AN2606 datasheet(22/155 Pages) STMICROELECTRONICS

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General bootloader description

AN2606

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DocID13801 Rev 21

location, make sure that the relative protection bit (in the last 16 bytes of the OTP

memory) is not reset.

•

For STM32 F2 and F4 series the internal flash write operation format depends on the

voltage range. By default write operation are allowed by one byte format (Half-Word,

Word and Double-Word operations are not allowed). To increase the speed of write

operation, the user should apply the adequate voltage range that allows write operation

by Half-Word, Word or Double-Word and update this configuration on the fly by the

bootloader software through a virtual memory location. This memory location is not

physical but can be read and written using usual bootloader read/write operations

according to the protocol in use. This memory location contains 4 bytes which are

described in table below. It can be accessed by 1, 2, 3 or 4 bytes. However, reserved

bytes should remain at their default values (0xFF), otherwise the request will be

NACKed.

Table 4. STM32 F2 and F4 Voltage Range configuration using bootloader

The table below lists the valid memory area depending on the Bootloader commands.

Address

Size

Description

0xFFFF0000

1 byte

This byte controls the current value of the voltage range.

0x00: voltage range [1.8 V, 2.1 V]

0x01: voltage range [2.1 V, 2.4 V]

0x02: voltage range [2.4 V, 2.7 V]

0x03: voltage range [2.7 V, 3.6 V]

0x04: voltage range [2.7 V, 3.6 V] and double word write/erase

operation is used. In this case it is mandatory to supply 9 V

through the VPP pin (refer to the product reference manual for

more details about the double-word write procedure).

Other: all other values are not supported and will be NACKed.

0xFFFF0001

1 byte

Reserved.

0xFF: default value.

Other: all other values are not supported and will be NACKed.

0xFFFF0002

1 byte

Reserved.

0xFF: default value.

Other: all other values are not supported and will be NACKed.

0xFFFF0003

1 byte

Reserved.

0xFF: default value.

Other: all other values are not supported and will be NACKed.

Table 5. Supported memory area by Write, Read, Erase and Go Commands

Memory Area

Write command

Read command

Erase command

Go command

Flash

Supported

RAM

Supported

Not Supported

Supported

System Memory

Not Supported

Supported

Not Supported

Data Memory

Supported

Not Supported

OTP Memory

Supported

Not Supported

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