AT32F425
Series Reference Manual
2022.03.30
Page 46
Ver 2.01
external interrupt line in Interrupt mode can wake up the system from Deepsleep mode.
2)
When the Sleep mode is entered by executing a WFE instruction, the interrupt generated on any
external interrupt line in Event mode can wake up the system from Deepsleep mode.
When the MCU exits the Deepsleep mode, the HICK RC oscillator is enabled and selected as a system
clock after stabilization.When the LDO operates in low-power mode, an additional wakeup delay is
incurred for the reason that the LDO must be stabilized before the system is waken from the Deepsleep
mode.
Standby Mode
Standby mode can achieve the lowest power consumption for the device. In this mode, the LDO is
disabled. The whole 1.2 V domain, PLL, HICK and HEXT oscillators are also powered off except
VDD/VDDA domain. SRAM and register contents are lost.
The Standby mode is entered by the following procedures:
–
Set the SLEEPDEE bit in the Cortex
™
-M4 system control register
–
Set the LPSEL bit in the power control register (PWC_CTRL)
–
Clear the SWEF bit in the power control/status register (PWC_CTRLSTS)
–
Execute a WFI/WFE instruction
In Standby mode, all I/O pins remain in a high-impedance state except reset pins, TAMPER pins that
are set as anti-tamper or calibration output, and the wakeup pins enabled.
The MCU leaves the Standby mode when an external reset (NRST pin), an WDT reset, ERTC periodic
wakeup, ERTC timestamp, ERTC tamper event and a rising edge on the WKUP pin or the rising edge
of an ERTC alarm event occurs.
Debug mode
By default, the debug connection is lost if the MCU enters Deepsleep mode or Standby mode while
debugging. The reason is that the Cortex
™
-M4 core is no longer clocked. However, the software can be
debugged even in the low-power mode by setting some configuration bits in the DEBUG register
(DEBUG_CTRL).
3.7 PWC registers
The peripheral registers must be accessed by words (32 bit)
Table 3-1 PW register map and reset values
Register abbr.
Offset
Reset value
PWC_CTRL
0x00
0x0000 0000
PWC_CTRLSTS
0x04
0x0000 0000
PWC_CTRL2
0x20
0x0000 0080