NRF52820-QDAA-R datasheet(58/437 Pages) NORDIC

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Power and clock management

5.3.6.7 Retained registers

A retained register is one that will retain its value in System OFF mode and through a reset, depending

on the reset source. See the individual peripheral chapters for information on which of their registers are

retained.

5.3.6.8 Reset behavior

The various reset sources and their targets are summarized in the table below.

Reset target

Reset source

CPU

Peripherals GPIO

Debug4

SWJ-DP

RAM

WDT

Retained

registers

RESETREAS

CPU lockup 5

Soft reset

Wakeup from System OFF

mode reset

x 6

x 7

Watchdog reset 8

Pin reset

Brownout reset

Power-on reset

Note: The RAM is never reset, but depending on a reset source the content of RAM may be

corrupted.

5.3.7 Registers

Base address

Peripheral

Instance

Description

Configuration

0x40000000

POWER

Power control

Table 16: Instances

Offset

Description

TASKS_CONSTLAT

0x78

Enable Constant Latency mode

TASKS_LOWPWR

0x7C

Enable Low-power mode (variable latency)

EVENTS_POFWARN

0x108

Power failure warning

EVENTS_SLEEPENTER

0x114

CPU entered WFI/WFE sleep

EVENTS_SLEEPEXIT

0x118

CPU exited WFI/WFE sleep

EVENTS_USBDETECTED

0x11C

Voltage supply detected on VBUS

EVENTS_USBREMOVED

0x120

Voltage supply removed from VBUS

EVENTS_USBPWRRDY

0x124

USB 3.3 V supply ready

INTENSET

0x304

Enable interrupt

INTENCLR

0x308

Disable interrupt

4 All debug components excluding SWJ-DP. See Debug on page 40 for more information about the

different debug components.

5 Reset from CPU lockup is disabled if the device is in Debug Interface mode. CPU lockup is not

possible in System OFF.

6 The debug components will not be reset if the device is in Debug Interface mode.

7 RAM is not reset on wakeup from System OFF mode. RAM, or certain parts of RAM, may not be

retained after the device has entered System OFF mode, depending on the settings in the RAM

registers.

8 Watchdog reset is not available in System OFF.

4463_156 v1.0

NRF52820-QDAA-R Datasheet(PDF) 58 Page - Nordic Semiconductor

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