Inter-Integrated Circuit(I²C)Bus

7/30/2019 Inter-Integrated Circuit(IC)Bus

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Inter-Integrated Circuit(IC)Bus


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Covered Topics

Overview of I2C

Using I2C on the PICmicro Microcontroller

Example: A code walk-though for connecting aEEPROM to a PIC16 Microcontroller


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Overview of I2C

Used for moving data simply and quickly

from one device to another

Serial Interface Synchronous

Bidirectional


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Overview of I2C

I2C is a Synchronous protocol

The data is clocked along the clock signa(SCL)

The clock signal controls when data is changedand when it should be read

I2C is a Bidirectional protocol

Data is sent either direction on the serial dataline (SDA) by the master or slave.


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Overview of I2C

I2C is a Master-Slave protocol

The Master device controls the clock (SCL)

The slave devices may hold the clock low toprevent data transfer

No data is transferred unless a clock signal is

present All slaves are controlled by the master clock


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Overview of I2C Signals

I2C is a Serial Interface of only two signals:

SDA Serial DAta

This line transfers data to or from the master.

SCL Serial CLock

This controls when data is sent and when it isread. The master controls SCK.


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I2C Supporting Speeds

Operates up to 100 kbit/s in the Standard-

mode, up to 400 kbit/s in the Fast-mode, and

up to 3.4 Mbit/s in the High-speed mode


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I2C- Signals


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I2C- Pull up Resistor


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I2C- Elements

Building Blocks of I2C

S= Start P= Stop R= Restart A= Ack

sS P R Data A


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I2C Elements Start Condition


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I2C Elements Stop Condition


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I2C Elements -Restart Condition


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I2C Elements- Data


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I2C Elements- Data


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I2C Elements- ACK


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I2C Elements- Nack


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I2C Addressing


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I2C Interfacing


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I2C Arbitration

If two or more masters try to put informationto the bus, the first to produce a one when

the other produces a zero will lose the

arbitration. Arbitration can continue for manybits. Its first stage is comparison of the

address If the masters are each trying to

address the same device arbitration continues

with comparison of the data. Because address

and data information on the I2C-bus is used

for arbitration, no information is lost during

this process.


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Writing to a I2C EEPROM


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Reading from an I2C EEPROM


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Writing to a Larger EEPROM


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I2C in the PIC micro MCU

Registers control the function I2C in the PIC

micro microcontroller

The values to be placed in the registers will

often depend on the application


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SSPCON Register

SSPCON Register:

WCOL Write Collision

SSPOV Overflow SSPEN Enable

SSPM3:SSPM0 (4 bits) Function Control

CKP is also in SSPCON but is not used for

master mode I2C.


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SSPCON2 Register

GCEN General Call Enable

ACKSTAT ACK Bit Status

ACKDT ACK Transmit Data

ACKEN ACK Transmit Enable

RCEN Receive Enable

PEN Stop Condition Enable

RSEN Restart Condition Enable

SEN Start Condition Enable


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SSPSTAT Register

SMP Slew Rate Control

CKE Signal Level Control

BF Buffer full


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SSPADD Register

The SSPADD register controls the speed of

the I2C bus transmissions. It controls the baud

rate generator.


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I2C -- Code Example -Write


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I2C -- Code Example - Read


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Reference

Application NotesAN734, AN735 and AN578

from Microchip

Documents

Inter-Integrated Circuit(I²C)Bus