Datasheet

Functional overview STM32F412xE/G
24/193 DocID028087 Rev 4
3.16 Boot modes
At startup, boot pins are used to select one out of three boot options:
• Boot from user Flash memory
• Boot from system memory
• Boot from embedded SRAM
The boot loader is located in system memory. It is used to reprogram the Flash memory by
using one of the interface listed in the Table 3 or the USB OTG FS in device mode through
DFU (device firmware upgrade).
For more detailed information on the bootloader, refer to Application Note: AN2606,
STM32™ microcontroller system memory boot mode.
3.17 Power supply schemes
• V
DD
= 1.7 to 3.6 V: external power supply for I/Os with the internal supervisor
(POR/PDR) disabled, provided externally through V
DD
pins. Requires the use of an
external power supply supervisor connected to the V
DD
and NRST pins.
• V
SSA
, V
DDA
= 1.7 to 3.6 V: external analog power supplies for ADC, Reset blocks, RCs
and PLL. V
DDA
and V
SSA
must be connected to V
DD
and V
SS
, respectively, with
decoupling technique.
Note: The V
DD
/V
DDA
minimum value of 1.7 V is obtained with the use of an external power supply
supervisor (refer to
Section 3.18.2: Internal reset OFF). Refer to Table 4: Regulator ON/OFF
and internal power supply supervisor availability to identify the packages supporting this
option.
• V
BAT
= 1.65 to 3.6 V: power supply for RTC, external clock 32 kHz oscillator and
backup registers (through power switch) when V
DD
is not present.
• V
DDUSB
can be connected either to VDD or an external independent power supply (3.0
to 3.6 V) for USB transceivers.
For example, when device is powered at 1.8 V, an independent power supply 3.3V can
be connected to V
DDUSB
. When the V
DDUSB
is connected to a separated power supply,
Table 3. Embedded bootloader interfaces
Package
USART1
PA9/
PA10
USART2
PD6/
PD5
USART3
PB11/
PB10
I2C1
PB6/
PB7
I2C2
PF0/
PF1
I2C3
PA8/
PB4
I2C
FMP1
PB14/
PB15
SPI1
PA4/
PA5/
PA6/
PA7
SPI3
PA15/
PC10/
PC11/
PC12
SPI4
PE11/
PE12/
PE13/
PE14
CAN2
PB5/
PB13
USB
PA11
/P12
UFQFPN48 Y - - Y - Y Y Y - - Y Y
WLCSP64 Y - - Y - Y Y Y Y - Y Y
LQFP64 Y - - Y - Y Y Y Y - Y Y
LQFP100Y Y - Y-YYYYYYY
LQFP144YYYYYYYYYYYY
UFBGA100 Y Y Y Y - Y Y Y Y Y Y Y
UFBGA144 Y Y Y Y Y Y Y Y Y Y Y Y
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