HT45F75 datasheet(125/190 Pages) HOLTEK

125 / 190 page

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HT45F75

Body Fat Scale Flash MCU

HT45F75

Body Fat Scale Flash MCU

St ar t

Wr it e Sl av e

Ad dr es s to S IM A

SE T SI M[ 2: 0] =1 10

SE T SI ME N

I 2 C Bu s

In te rr upt =?

Ye s

Se t S IE a nd M Fn E

Wa it fo r In te rru pt

Go to M ai n Pr ogr am

Cl r SI E

Po ll S IF t o de ci de

wh en t o go t o I 2 C Bu s IS R

Go to M ai n Pr ogr am

I2C Bus Initialisation Flow Chart

I2C Bus Start Signal

TheSTARTsignalcanonlybegeneratedbythemasterdeviceconnectedtotheI2Cbusandnotby

theslavedevice.ThisSTARTsignalwillbedetectedbyalldevicesconnectedtotheI2Cbus.When

detected,thisindicatesthattheI2CbusisbusyandthereforetheHBBbitwillbeset.ASTART

conditionoccurswhenahightolowtransitionontheSDAlinetakesplacewhentheSCLline

remainshigh.

Slave Address

ThetransmissionofaSTARTsignalbythemasterwillbedetectedbyalldevicesontheI2Cbus.

Todeterminewhichslavedevicethemasterwishestocommunicatewith,theaddressoftheslave

devicewillbesentoutimmediatelyfollowingtheSTARTsignal.Allslavedevices,afterreceiving

this7-bitaddressdata,willcompareitwiththeirown7-bitslaveaddress.Iftheaddresssentoutby

themastermatchestheinternaladdressofthemicrocontrollerslavedevice,thenaninternalI2Cbus

interruptsignalwillbegenerated.Thenextbitfollowingtheaddress,whichisthe8thbit,defines

theread/writestatusandwillbesavedtotheSRWbitoftheSIMC1register.Theslavedevicewill

thentransmitanacknowledgebit,whichisalowlevel,asthe9thbit.Theslavedevicewillalsoset

thestatusflagHAASwhentheaddressesmatch.

AsanI2Cbusinterruptcancomefromtwosources,whentheprogramenterstheinterrupt

subroutine,theHAASbitshouldbeexaminedtoseewhethertheinterruptsourcehascomefrom

amatchingslaveaddressorfromthecompletionofadatabytetransfer.Whenaslaveaddressis

matched,thedevicemustbeplacedineitherthetransmitmodeandthenwritedatatotheSIMD

releasetheSCLline.

I2C Bus Read/Write Signal

TheSRWbitintheSIMC1registerdefineswhethertheslavedevicewishestoreaddatafromthe

I2CbusorwritedatatotheI2Cbus.Theslavedeviceshouldexaminethisbittodetermineifitisto

beatransmitterorareceiver.IftheSRWflagis“1”thenthisindicatesthatthemasterdevicewishes

toreaddatafromtheI2Cbus,thereforetheslavedevicemustbesetuptosenddatatotheI2Cbusas

atransmitter.IftheSRWflagis“0”thenthisindicatesthatthemasterwishestosenddatatotheI2C

bus,thereforetheslavedevicemustbesetuptoreaddatafromtheI2Cbusasareceiver.

HT45F75 Datasheet(PDF) 125 Page - Holtek Semiconductor Inc

HT45F75 Datasheet(HTML) 125 Page - Holtek Semiconductor Inc

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