(Philips)THE I2C-BUS SPECIFICATION,VERSION 2.1,JANUARY 2000

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CONTENTS
1 PREFACE. . . . . . . . . . . . . . . . . . . . . . . . . . .3
1.1 Version 1.0 - 1992. . . . . . . . . . . . . . . . . . . . 3
1.2 Version 2.0 - 198. . . . . . . . . . . . . . . . . . . . . 3
1.3 Version 2.1 - 1999. . . . . . . . . . . . . . . . . . . . 3
1.4 Purchase of Philips I2C-bus components . . 3
2 THE I2C-BUS BENEFITS DESIGNERS
AND MANUFACTURERS. . . . . . . . . . . . . . .4
2.1 Designer benefits . . . . . . . . . . . . . . . . . . . . 4
2.2 Manufacturer benefits . . . . . . . . . . . . . . . . . 6
3 INTRODUCTION TO THE I2C-BUS
SPECIFICATION . . . . . . . . . . . . . . . . . . . . .6
4 THE I2C-BUS CONCEPT . . . . . . . . . . . . . . .6
5 GENERAL CHARACTERISTICS . . . . . . . . .8
6 BIT TRANSFER . . . . . . . . . . . . . . . . . . . . . .8
6.1 Data validity . . . . . . . . . . . . . . . . . . . . . . . . 8
6.2 START and STOP conditions . . . . . . . . . . . 9
7 TRANSFERRING DATA . . . . . . . . . . . . . . .10
7.1 Byte format . . . . . . . . . . . . . . . . . . . . . . . . 10
7.2 Acknowledge. . . . . . . . . . . . . . . . . . . . . . . 10
8 ARBITRATION AND CLOCK
GENERATION . . . . . . . . . . . . . . . . . . . . . .11
8.1 Synchronization . . . . . . . . . . . . . . . . . . . . 11
8.2 Arbitration . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.3 Use of the clock synchronizing
mechanism as a handshake . . . . . . . . . . . 13
9 FORMATS WITH 7-BIT ADDRESSES . . . .13
10 7-BIT ADDRESSING . . . . . . . . . . . . . . . . .15
10.1 Definition of bits in the first byte . . . . . . . . 15
10.1.1 General call address . . . . . . . . . . . . . . . . . 16
10.1.2 START byte . . . . . . . . . . . . . . . . . . . . . . . 17
10.1.3 CBUS compatibility . . . . . . . . . . . . . . . . . . 18
11 EXTENSIONS TO THE STANDARDMODE
I2C-BUS SPECIFICATION . . . . . . .19
12 FAST-MODE. . . . . . . . . . . . . . . . . . . . . . . .19
13 Hs-MODE . . . . . . . . . . . . . . . . . . . . . . . . . .20
13.1 High speed transfer. . . . . . . . . . . . . . . . . . 20
13.2 Serial data transfer format in Hs-mode . . . 21
13.3 Switching from F/S- to Hs-mode and
back . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
13.4 Hs-mode devices at lower speed modes. . 24
13.5 Mixed speed modes on one serial bus
system . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
13.5.1 F/S-mode transfer in a mixed-speed bus system .. 25
13.5.2 Hs-mode transfer in a mixed-speed bus system  . . 25
13.5.3 Timing requirements for the bridge in a mixed-speed bus system.. 27
14 10-BIT ADDRESSING . . . . . . . . . . . . . . . . 27
14.1 Definition of bits in the first two bytes. . . . . 27
14.2 Formats with 10-bit addresses. . . . . . . . . . 27
14.3 General call address and start byte with 10-bit addressing . . 30
15 ELECTRICAL SPECIFICATIONS AND TIMING FOR I/O STAGES AND BUS LINES .30
15.1 Standard- and Fast-mode devices. . . . . . . 30
15.2 Hs-mode devices . . . . . . . . . . . . . . . . . . . . 34
16 ELECTRICAL CONNECTIONS OF I2C-BUS DEVICES TO THE BUS LINES . 37
16.1 Maximum and minimum values of resistors Rp and Rs for Standard-mode
        I2C-bus devices . . . . . . . . . . . . . . . . . . . . . 39
17 APPLICATION INFORMATION. . . . . . . . . 41
17.1 Slope-controlled output stages of Fast-mode I2C-bus devices . . . . 41
17.2 Switched pull-up circuit for Fast-mode I2C-bus devices . . . . . 41
17.3 Wiring pattern of the bus lines . . . . . . . . . . 42
17.4 Maximum and minimum values of resistors Rp and Rs for Fast-mode                       I2C-bus devices . . . . . . . . . . . . . . . . . . . . . 42
17.5 Maximum and minimum values of resistors Rp and Rs for Hs-mode
        I2C-bus devices . . . . . . . . . . . . . . . . . . . . . 42
18 BI-DIRECTIONAL LEVEL SHIFTER FOR F/S-MODE I2C-BUS SYSTEMS . . . . 42
18.1 Connecting devices with different logic levels . . . . . . . . . . . . . . . 43
18.1.1 Operation of the level shifter . . . . . . . . . . . 44
19 DEVELOPMENT TOOLS AVAILABLE FROM PHILIPS  . . . . . . . . 45
20 SUPPORT LITERATURE . . . . . . . . . . . . . 46

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