Connect I²C with PIC




The I²C full master MSSP module is available with a number of PIC MCU models. mikroC PRO for PIC provides library which supports the master I²C mode.

  Important :

  • Some MCUs have multiple I²C modules. In order to use the desired I²C library routine, simply change the number 1 in the prototype with the appropriate module number, i.e. I2C2_Init(100000);Connect I²C with PIC

Library Routines

  • I2C1_Init
  • I2C1_Start
  • I2C1_Repeated_Start
  • I2C1_Is_Idle
  • I2C1_Rd
  • I2C1_Wr
  • I2C1_Stop

I2C1_Init

Prototype void I2C1_Init(const unsigned long clock);
Returns Nothing.
Description Initializes I²C with desired clock (refer to device data sheet for correct values in respect with Fosc). Needs to be called before using other functions of I²C Library.
You don’t need to configure ports manually for using the module; library will take care of the initialization.
Requires Library requires MSSP module.

  Note : Calculation of the I²C clock value is carried out by the compiler, as it would produce a relatively large code if performed on the library level. Therefore, compiler needs to know the value of the parameter in the compile time. That is why this parameter needs to be a constant, and not a variable.
Example
I2C1_Init(100000);

I2C1_Start

Prototype unsigned short I2C1_Start(void);
Returns If there is no error, function returns 0.
Description Determines if I²C bus is free and issues START signal.
Requires I²C must be configured before using this function.
Example
I2C1_Start();

I2C1_Repeated_Start

Prototype void I2C1_Repeated_Start(void);
Returns Nothing.
Description Issues repeated START signal.
Requires I²C must be configured before using this function.
Example
I2C1_Repeated_Start();

I2C1_Is_Idle

Prototype unsigned short I2C1_Is_Idle(void);
Returns Returns 1 if I²C bus is free, otherwise returns 0.
Description Tests if I²C bus is free.
Requires I²C must be configured before using this function.
Example
if (I2C1_Is_Idle()) {...}

I2C1_Rd

Prototype unsigned short I2C1_Rd(unsigned short ack);
Returns Returns one byte from the slave.
Description Reads one byte from the slave, and sends not acknowledge signal if parameter ack is 0, otherwise it sends acknowledge.
Requires I²C must be configured before using this function.
Also, START signal needs to be issued in order to use this function.
Example Read data and send not acknowledge signal:

unsigned short take;
...
take = I2C1_Rd(0);

I2C1_Wr

Prototype unsigned short I2C1_Wr(unsigned short data_);
Returns Returns 0 if there were no errors.
Description Sends data byte (parameter data) via I²C bus.
Requires I²C must be configured before using this function.
Also, START signal needs to be issued in order to use this function.
Example
I2C1_Write(0xA3);

I2C1_Stop

Prototype void I2C1_Stop(void);
Returns Nothing.
Description Issues STOP signal.
Requires I²C must be configured before using this function.
Example
I2C1_Stop();

Connect I²C with PIC schematichCode Example

This code demonstrates use of I²C library. PIC MCU is connected (SCL, SDA pins) to 24c02 EEPROM. Program sends data to EEPROM (data is written at address 2). Then, we read data via I²C from EEPROM and send its value to PORTB, to check if the cycle was successful (see the figure below how to interface 24c02 to PIC).

For more detail: Connect I²C with PIC




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