NRF52820-QDAA-R datasheet(81/437 Pages) NORDIC

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Power and clock management

Bit number

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

A A

Reset 0x00000000

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Access

Field

Value ID

Value

Description

SRC

Clock source

32.768 kHz RC oscillator (LFRC)

Xtal

32.768 kHz crystal oscillator (LFXO)

Synth

32.768 kHz synthesized from HFCLK (LFSYNT)

5.4.3.21 LFCLKSRC

Address offset: 0x518

Clock source for the LFCLK

Bit number

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

C B

A A

Reset 0x00000000

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Access

Field

Value ID

Value

Description

RW SRC

Clock source

32.768 kHz RC oscillator (LFRC)

Xtal

32.768 kHz crystal oscillator (LFXO)

Synth

32.768 kHz synthesized from HFCLK (LFSYNT)

RW BYPASS

Enable or disable bypass of LFCLK crystal oscillator with

external clock source

Disabled

Disable (use with Xtal or low-swing external source)

Enabled

Enable (use with rail-to-rail external source)

RW EXTERNAL

Enable or disable external source for LFCLK

Disabled

Disable external source (use with Xtal)

Enabled

Enable use of external source instead of Xtal (SRC needs to

be set to Xtal)

5.4.3.22 HFXODEBOUNCE

Address offset: 0x528

HFXO debounce time. The HFXO is started by triggering the TASKS_HFCLKSTART task.

The EVENTS_HFCLKSTARTED event is generated after the HFXO power up time + the HFXO debounce time

has elapsed. It is not allowed to change the value of this register while the HFXO is starting.

Bit number

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

A A A A A A A A

Reset 0x00000010

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0

Access

Field

Value ID

Value

Description

RW HFXODEBOUNCE

0x01..0xFF

HFXO debounce time. Debounce time = HFXODEBOUNCE *

16 µs.

Db256us

0x10

256 µs debounce time. Recommended for 1.6 mm x 2.0 mm

crystals and larger.

Db1024us

0x40

1024 µs debounce time. Recommended for 1.6 mm x 1.2

mm crystals and smaller.

5.4.3.23 LFXODEBOUNCE

Address offset: 0x52C

4463_156 v1.0

NRF52820-QDAA-R Datasheet(PDF) 81 Page - Nordic Semiconductor

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