4 Boot management

AN1775

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4

Boot management

Three different boot modes are available and can be enabled by means of three input pins:

BOOTEN, BOOT0 and BOOT1.

The following table describes the different boot mode configurations.

The following figure gives an implementation example of boot management for STR71x

devices. BOOT0 and BOOT1 are alternate function pins used for boot configuration during the

RESET phase (floating-input configuration), so they can be used afterwards in the application

as standard I/Os. For more details concerning boot configuration, refer to the device reference

manual.

Figure 7.

Boot mode selection implementation example

Note: 1 As the nSTDBY pin has a floating input configuration, an external pull-up has to be provided to

avoid remaining in stand-by mode.

2 The TEST pin of the STR71x must always be forced to ground (ST reserved test pin)

BOOTEN

BOOT0

BOOT1

BOOT Mode

0x

x

USER: boot from internal FLASH memory

100

110

Reserved

1

0

1

RAM: boot from internal RAM memory

111

EXTMEM: boot from external memory mapped on the EMI interface

at 0000 0000h address.

STR71x

BOOT0

GND

* these values are given only as typical example

BOOTEN

10K*

3V3

10K*

3V3

GND

10K*

3V3

GND

BOOT1

nSTDBY

10K*

3V3

TEST

GND