Datasheet

COMMUNICATIONS
I
2
CINTERFACE
Hostgenerated
A AS 0ADDR[6:0] CMD[7:0]
Sr
1ADDR[6:0] A DATA[7:0] A DATA[7:0] PN...
(d) incrementalread
A AS 0ADDR[6:0] CMD[7:0]
Sr
1ADDR[6:0] A DATA[7:0] PN
(c) 1- byteread
A AS A0 PADDR[6:0] CMD[7:0] DATA [7:0]
(a) 1-bytewrite
(b) quickread
S 1ADDR[6:0] A DATA [7:0] PN
bq27510 generated
...A AS A0 PADDR[6:0] CMD[7:0] DATA [7:0] DATA [7:0] A A
(e) incrementalwrite
(S = Start, Sr = RepeatedStart, A = Acknowledge, N = No Acknowledge, andP = Stop).
S ADDR[6:0] 0 A CMD[7:0] A DATA[7:0] N P
S
ADDR[6:0]
0 A
CMD[7:0]
N P
I
2
CTIMEOUT
I
2
CCOMMANDWAITINGTIME
bq27510-G1
www.ti.com .....................................................................................................................................................................................................SLUS927–APRIL2009
Thebq27510supportsthestandardI
2
Cread,incrementalread,quickread,onebytewrite,andincrementalwrite
functions.The7bitdeviceaddress(ADDR)isthemostsignificant7bitsofthehexaddressandisfixedas
1010101.The8-bitdeviceaddresswillthereforebe0xAAor0xABforwriteorread,respectively.
Figure4.SupportedI
2
CFormats
The“quickread”returnsdataattheaddressindicatedbytheaddresspointer.Theaddresspointer,aregister
internaltotheI
2
Ccommunicationengine,willincrementwheneverdataisacknowledgedbythebq27510orthe
I
2
Cmaster.“Quickwrites”functioninthesamemannerandareaconvenientmeansofsendingmultiplebytesto
consecutivecommandlocations(suchastwo-bytecommandsthatrequiretwobytesofdata)
Thefollowingcommandsequencesarenotsupported:
Attempttowritearead-onlyaddress(NACKafterdatasentbymaster):
Attempttoreadanaddressabove0x6B(NACKcommand):
TheI
2
CenginewillreleasebothSDAandSCLiftheI2Cbusisheldlowforabout2seconds.Ifthebq27510was
holdingthelines,releasingthemwillfreeforthemastertodrivethelines.Ifanexternalconditionisholdingeither
ofthelineslow,theI
2
Cenginewillenterthelowpowersleepmode.
Tomakesurethecorrectresultsofacommandwiththe400kHzI
2
Coperation,aproperwaitingtimeshouldbe
addedbetweenissuingcommandandreadingresults.Forsubcommands,thefollowingdiagramshowsthe
waitingtimerequiredbetweenissuingthecontrolcommandthereadingthestatuswiththeexceptionof
checksumcommand.A100mswaitingtimeisrequiredbetweenthechecksumcommandandreadingresult.For
read-writestandardcommands,aminimumof2secondsisrequiredtogettheresultupdated.Forread-only
standardcommands,thereisnowaitingtimerequired,butthehostshouldnotissueallstandardcommands
morethantwotimespersecond.Otherwise,thegaugecouldresultinaresetissueduetotheexpirationofthe
watchdogtimer.
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Not Recommended For New Designs