STM32L471RG datasheet(19/218 Pages) STMICROELECTRONICS

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STM32L471xx

Functional overview

3.7

Boot modes

At startup, BOOT0 pin and BOOT1 option bit are used to select one of three boot options:

•

Boot from user Flash

•

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 USART, I2C, SPI and CAN in Device mode through DFU (device firmware upgrade).

3.8

Cyclic redundancy check calculation unit (CRC)

The CRC (cyclic redundancy check) calculation unit is used to get a CRC code using a

configurable generator polynomial value and size.

Among other applications, CRC-based techniques are used to verify data transmission or

storage integrity. In the scope of the EN/IEC 60335-1 standard, they offer a means of

verifying the Flash memory integrity. The CRC calculation unit helps compute a signature of

the software during runtime, to be compared with a reference signature generated at link-

time and stored at a given memory location.

3.9

Power supply management

3.9.1

Power supply schemes

•

VDD = 1.71 to 3.6 V: external power supply for I/Os (VDDIO1), the internal regulator and

the system analog such as reset, power management and internal clocks. It is provided

externally through VDD pins.

•

VDDA = 1.62 V (ADCs/COMPs) / 1.8 (DACs/OPAMPs) to 3.6 V: external analog power

supply for ADCs, DACs, OPAMPs, Comparators and Voltage reference buffer. The

VDDA voltage level is independent from the VDD voltage.

•

VDDIO2 = 1.08 to 3.6 V: external power supply for 14 I/Os (PG[15:2]). The VDDIO2

voltage level is independent from the VDD voltage.

•

VBAT = 1.55 to 3.6 V: power supply for RTC, external clock 32 kHz oscillator and

backup registers (through power switch) when VDD is not present.

Note:

When the functions supplied by VDDA or VDDIO2 are not used, these supplies should

preferably be shorted to VDD.

Note:

If these supplies are tied to ground, the I/Os supplied by these power supplies are not 5 V

tolerant (refer to Table 19: Voltage characteristics).

Note:

VDDIOx is the I/Os general purpose digital functions supply. VDDIOx represents VDDIO1 or

VDDIO2, with VDDIO1 = VDD. VDDIO2 supply voltage level is independent from VDDIO1.

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