HT45F65 datasheet(164/231 Pages) HOLTEK

164 / 231 page

Rev. 1.60

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Rev. 1.60

16�

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HT45F65/HT45F66/HT45F67

Glucose Meter 8-Bit Flash MCU

I2C Bus Communication

CommunicationontheI2Cbusrequiresfourseparatesteps,aSTARTsignal,aslavedeviceaddress

transmission,adatatransmissionandfinallyaSTOPsignal.WhenaSTARTsignalisplacedon

theI2Cbus,alldevicesonthebuswillreceivethissignalandbenotifiedoftheimminentarrivalof

dataonthebus.Thefirstsevenbitsofthedatawillbetheslaveaddresswiththefirstbitbeingthe

MSB.Iftheaddressoftheslavedevicematchesthatofthetransmittedaddress,theHAASbitinthe

SIMC1registerwillbesetandanI2Cinterruptwillbegenerated.Afterenteringtheinterruptservice

routine,theslavedevicemustfirstchecktheconditionoftheHAASbittodeterminewhetherthe

interruptsourceoriginatesfromanaddressmatchorfromthecompletionofan8-bitdatatransfer.

Duringadatatransfer,notethatafterthe7-bitslaveaddresshasbeentransmitted,thefollowingbit,

whichisthe8thbit,istheread/writebitwhosevaluewillbeplacedintheSRWbit.Thisbitwillbe

checkedbytheslavedevicetodeterminewhethertogointotransmitorreceivemode.Beforeany

transferofdatatoorfromtheI2Cbus,themicrocontrollermustinitialisethebus,thefollowingare

stepstoachievethis:

• Step1

SettheSIM2~SIM0andSIMENbitsintheSIMC0registerto"1"toenabletheI2Cbus.

• Step2

WritetheslaveaddressofthedevicetotheI2CbusaddressregisterSIMA.

• Step3

SettheSIMEandSIMMuti-Functioninterruptenablebitoftheinterruptcontrolregisterto

enabletheSIMinterruptandMulti-functioninterrupt.

St ar t

Wr it e Sl av e

A ddr e ss 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 up t= ?

Ye s

SE T SI ME a nd MF nE

Wa it f or I nt e rr upt

Go to M ai n Pr og ra m

CL R SI ME

Po ll S IM F to d ec i de

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

Go to M ai n Pr og ra m

I2C Bus Initialisation Flow Chart

I2C Bus Start Signal

TheSTARTsignalcanonlybegeneratedbythemasterdeviceconnectedtotheI2Cbusandnotby

theslavedevice.ThisSTARTsignalwillbedetectedbyalldevicesconnectedtotheI2Cbus.When

detected,thisindicatesthattheI2CbusisbusyandthereforetheHBBbitwillbeset.ASTART

conditionoccurswhenahightolowtransitionontheSDAlinetakesplacewhentheSCLline

remainshigh.

HT45F65 Datasheet(PDF) 164 Page - Holtek Semiconductor Inc

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