SI4021 datasheet(18/35 Pages) SILABS

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Si4021

Simultaneously Pressed Push-Button Detect by Microcontroller

Vdd

Microcontroller mode

SPI

nIRQ

POR

(internal)

Push button

input 2

Push button

input 1

POR

PB1

PB2

PB1

PB2

PB1

Status rd

PB_nIRQdly*

Note:

*PB_nIRQdly is equal with the

debounce time

Simplified Block Diagram of Push-Button 1–4 Inputs

To Digital glitch filter for

Push-button4

Push-button1,2,3

CLR

EVENT FLAG

SLEEP Command *

STAT. REG. READ Command **

COUNT/SINGLE

VDD

Note:

* In EEprom mode

** In uC controlled mode

Push-button1

Push-button2

Push-button4

Internal

blocker signal

Push-button1

and

Push-button2

WEAK PULL-UP

ENABLE/DISABLE

VDD

With internal weak pull-up

POR, LBD, WAKE UP TIMER,

P. BUTTONS EVENT FLAGS

Notice:

Only one EVENT is

serviced simultaneously

the others are pending.

Digital glitch

filter

CLK

CLR for P.B1,2

b1, b2, b3

SI4021 Datasheet(PDF) 18 Page - Silicon Laboratories

SI4021 Datasheet(HTML) 18 Page - Silicon Laboratories

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