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projects:electronics:stm32:stm32u0_notes

STM32U0 Notes

Literature

Development Boards

Operating Conditions

  • VDDx
    • 1.71 ≤ VDDx ≤ 3.60 V (absolute maximum: 4.00 V)
    • Nucleo-083RC LEDs become very dim when 3.3V net falls below 1.80 V
  • Brownout Reset1)
    • Selectable: 1.7, 2.0, 2.2, 2.5 or 2.8 V

Native USB (STM32U073, STM32U083)

In order to use the native USB for programming on pins PA11 and PA12, the following settings must be done in STM32CubeProgrammer –> Option bytes –> User Configuration.

Option byte name Value Description Notes
NBOOT_SEL 0 (Unchecked) BOOT0 pin (legacy mode) :!: Factory setting is 1. You must change it to 0 to keep USB DFU programming capability. :!:
nBOOT1 1 (Checked) Boot from Flash if BOOT0 = 1, otherwise System Memory This is the factory setting
NRST_MODE 1 or 3 1: Reset input only
3. Bidirectional reset: The NRST pin is configured in reset input/output (legacy) mode
3 is the factory setting

STM32duino LowPower & RTC

State Peripherals Memory Voltage Supplies (VDDx) STM32RTC::LSI_CLOCK STM32RTC::LSE_CLOCK :!: STM32RTC::HSE_CLOCK :!:
LowPower.idle() On On On Supported Supported Supported
LowPower.sleep() On On On Supported Supported Supported
LowPower.deepSleep() On On On Supported Supported Supported
LowPower.shutdown() :!: Off Off Off Supported

:!:: External hardware required

Prerequisites for LowPower.shutdown()

  • External 32.768 kHz crystal for LSE2)
  • rtc.setClockSource(STM32RTC::LSE_CLOCK);
    rtc.begin();

RTC Clock Sources

1)
RM0503, §3.7.7 FLASH option register (FLASH_OPTR), Bits 10:8 BOR_LEV[2:0]: BOR reset level
2)
DS14581/DS14548/DS14463, §6.3.7 External clock source characteristics, Low-speed external clock generated from a crystal resonator
projects/electronics/stm32/stm32u0_notes.txt · Last modified: 2025/03/12 16:22 by Andrew Yong