1. Historical background of I2C I2C from a hardware perspective Bus Architecture The Basic I2C Protocol...

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1 Table of contents CONTENTS 1. Historical background of I2C I2C from a hardware perspective Bus Architecture Basic Terminology The Basic I2C Protocol Flowchart Bus Events Additional Terminology Idle Bus START And STOP EVENTS START STOP Putting Information On The Bus Addressing A Slave The Addressing Debacle The RULE ACKNOWLEDGE nack or NOT ACK Key Elements To Remember Bus Stalling Getting Acknowledge From The MASTER s Perspective Giving Acknowledge From The MASTER s Perspective I2C Bus 3

2 Historical background of I2C Giving not ACK From The MASTER s Perspective Exchanging Information Writing One Byte To A Slave Writing More Than One Byte To A Slave Reading One Byte From A Slave Reading Multiple Bytes From A Slave Determining The Slave Access Mode The Combined Data Format Multi Master Communication An Example Additional Testing Bus Synchronisation An Example Special Addresses And Exceptions General Call Address Configuration Call Interrupt Call Start Byte CBUS Address High speed Master Code bit Call Address Device ID Speed Modes Standard Mode Fast Mode I2C Bus

3 10.3. Fast Mode High Speed Mode Additional I2C USES SMbus Electrical Differences Speed and Timing Software Layer Application PMBUS Applications IPMI ATCA Electrical specifications of the I2C Bus Enhanced I2C (FAST Mode) Extended Addressing Designing the bus system Adressing Bus Expansion F.A.Q.: Hardware What is the maximum allowed length of the bus? I want to transport I2C over a long distance or off board I want to extend it ''by the book''. Is there something like a Buffer for I2C? NXP P87B NXP P82B NXP PCA I2C Bus 5

4 Historical background of I2C Hendon 5501 / Can i isolate an I2C bus? (using optocoupler or some other means) ADUM1250 / ADUM1251 / ADUM2250 / ADUM Homebrew What if I run out of addresses? Is there an I2C router? Using Generic Multiplexers Using Dedicated I2C Multiplexers Level shifting the I2C bus Is there something like a standalone I2C controller? Why does the clock line need to be bidirectional? F.A.Q.: Protocol Q. How do i generate a repeated start condition after the last byte? Q.What if I was in receive mode, how do i create the repeat start? Q. Is it okay to abort an ongoing transmission any time? Q. Do i need to give the ack in read mode on the last byte? Q&A SECTION: troubleshooting Q. Can i monitor an I2C bus in some way? USBee Q. Is there a way to test/debug I2C busses? Hardware Check Communication Check Corrupted Transport Multimaster Trouble Q. I want to experiment with I2C, Are there demo kits available? An I2C driver in PseudoCode I2C Bus

5 18. Debugging tools I2C Trigger Generator Checking Who Is Controlling The Bus I2C interfacing system for THE IBM PC Parallel PRinter Port Interface Software QuickBasic / PDS / POWERBasic / Visual basic Driver ACCESS Bus I2C In Your Computer Commonly used I2C devices I/O Expanders SAA bit I/O Expander PCF8574 / PCF8574A 8 bit I/O expander PCF bit I/O Expander MCP23017 MCP Non volatile Expander Other Expanders Applications LED And LCD Display Controllers LCD Display Modules LED DISPLAY Drivers LED Drivers A/D And D/A Converters Principles of Digital to Analog Converters Principles of ANALOG to Digital Converters I2C Bus 7

6 Historical background of I2C Things to Be Aware Of: Practical Converters with an I2C interface Audio And Video Circuitry EEPROM Memories E2Prom Technology FRAM Devices Real Time Clocks I2C Isolators Bus Multiplexers And Expanders Bus Multiplexers Master multiplexers Roll Your Own LabSticks I2C Introduction Board Board LabStick 1 1: I2C Probe Probe Hardware Command Set Base Commands Data Transport Simple Stream Examples Write a single byte to a slave device Write multiple bytes to a slave DEVICE Reading a byte from a slave Reading Multiple Bytes from a Slave: I2C Bus

7 Reading a byte from a Sub address using restart Support Functions Low Level Functions Assembly drawing Bill Of Materials LabStick 1 2: Universal Power Supply Assembly Drawing Bill Of Materials Selecting the output voltage LabStick 1 3: 24xxx eeprom Devices Up to 16Kbits Above 16Kbits Usage Devices up to and including 24C16 (8 bit memory address) Devices from 24C32 upwards (16 bit memory address) Pitfalls with E2PROMs Operating voltage and voltage range Page writing and page sizes Summary Assembly Drawing Bill Of Materials LabStick 1 4: PWM led controller Address Usage I2C Bus 9

8 Historical background of I2C Available registers Input register PCS0 and PCS1 register PWM0 and PWM1 register LED selector register USING as input Assembly Drawing Bill Of Materials LabStick 1 5: LCD / Keyboard user interface Initialization Device initialization LCD Display operation Keyboard Access Interrupt driven mode Polled mode Circuit Board Assembly LabStick 1 6: LM75 (A) temperature sensor Device Address Usage Pointer register: Configuration Register (01) Temperature register (00) Trip point register (Tos) (11) Hysteresis register (10) I2C Bus

9 27.3. Assembly Drawing Bill Of Materials LabStick 1 7: PCF8563 realtime clock Device Address Usage Control 1 register Control 2 register Seconds register Minutes register Hours register DAYS register Weekdays register Months register Years register Alarm Minutes register Alarm Hour register Alarm DAY register Alarm Weekday register CLK out control register Timer control register Timer register Alarm Operation Assembly Drawing Bill Of Materials LabStick 1 8: 8 Bit Protected Output I2C Bus 11

10 Historical background of I2C Assembly Bill Of Materials LabStick 1 9: 8 bit Protected Input Schematic Circuit Board Bill Of Materials Some Application Information LabStick 1 10: MCP4725 D/A converters Device Address Usage Control byte Data bytes Write datagram Read operations Read datagram Assembly Drawing Bill Of Materials LabStick 1 11: ADC081 / ADC101 / ADC121 A/D Converters Device Address Usage Selector register Conversion result register Alert status register Configuration register Low limit (underrange) trip point I2C Bus

11 High limit (overrange) trip point Alert hysteresis register Highest and lowest conversion registers Write Operations bit write bit write Read Operations Set pointer Retrieve 8 bit Retrieve 16 bit assembly drawing Bill Of Materials LabStick 1 12 PCF8591 Combined A/D and D/A Converter PCA Assembly Drawing Bill Of Materials LabStick 1 13: POTENTIOMETER Functional Differences Device Address Usage Writing the potentiometer Reading The D Version Reading Assembly Drawing I2C Bus 13

12 Historical background of I2C Bill Of Materials LabStick 1 14: PCA9544 I2C Multiplexer Device Address Usage Control word Interrupt logic Assembly Drawing Bill Of Materials LabStick 1 15: PCF8574(a) / PCA9xxx Universal I/O expander Schematic Device Address PCF PCF8574A Usage PCF8574 / PCF8574A / MAX7328 / MAX PCA PCA PCA9554 / PCA9554A PCA PCA PCA9674 / PCA9674A PCA Assembly Drawing Bill Of Materials LabStick 1 16: SAA segment display I2C Bus

13 37.1. Usage Status register (READ ONLY) Register select Control register Digit registers Assembly Drawing Bill Of Materials Appendix Part references Passive parts Semiconductors Appendix Additional Reading Index I2C Bus 15