I2C Library

I²C Library

The I²C full master I²C module is available with a number of the dsPIC30/33 and PIC24 MCU models. The mikroPascal PRO for dsPIC30/33 and PIC24 provides a library which supports the master I²C mode.

Important :

I²C library routines require you to specify the module you want to use. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3.
Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Init

Prototype	procedure I2Cx_Init(scl : longint);
Description	Configures and initializes the desired I²C module with default settings. This function enables the I²C module by setting the I2CEN bit. The rest of the bits in I²C control register remains unchanged. Default initialization (after reset) of I²C module is: continue operation in IDLE mode IPMI mode disabled 7-bit slave address slew rate control enabled general call address disabled software or receive clock stretching disabled
Parameters	`scl:` requested serial clock rate.
Returns	Nothing.
Requires	MCU with the I²C module.
Example	// Initialize the I2C1 module with clock_rate of 100000 I2C1_Init(100000);
Notes	Refer to the MCU's datasheet for correct values of the `scl` in respect with Fosc. I²C library routines require you to specify the module you want to use. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Start

Prototype	procedure I2Cx_Start();
Description	Determines if the I²C bus is free and issues START signal.
Parameters	None.
Returns	Nothing.
Requires	MCU with at least one I²C module. Used I²C module must be initialized before using this function. See I2Cx_Init routine.
Example	// Issue START signal I2C1_Start();
Notes	I²C library routines require you to specify the module you want to use. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Restart

Prototype	procedure I2Cx_Restart();
Description	Issues repeated START signal.
Parameters	None.
Returns	Nothing.
Requires	MCU with at least one I²C module. Used I²C module must be initialized before using this function. See I2Cx_Init routine.
Example	// Issue RESTART signal I2C1_Restart();
Notes	I²C library routines require you to specify the module you want to use. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Is_Idle

Prototype	function I2Cx_Is_Idle() : word;
Description	Waits for the I²C bus to become free. This is a blocking function.
Parameters	None.
Returns	`0` if I²C bus is free. `1` if I²C bus is not free.
Requires	MCU with at least one I²C module. Used I²C module must be initialized before using this function. See I2Cx_Init routine.
Example	var data_ : byte; ... if !(I2C1_Is_Idle) I2C1_Write(data_); ...
Notes	I²C library routines require you to specify the module you want to use. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Read

Prototype	function I2Cx_Read(ack : word) : byte;
Description	Reads a byte from the I²C bus.
Parameters	`ack:` acknowledge signal parameter. If the `ack = 0`, acknowledge signal will be sent after reading, otherwise the not acknowledge signal will be sent.
Returns	Received data.
Requires	MCU with at least one I²C module. Used I²C module must be initialized before using this function. See I2Cx_Init routine. Also, START signal needs to be issued in order to use this function. See I2Cx_Start.
Example	var take : byte; ... // Read data and send the not_acknowledge signal take := I2C1_Read(1);
Notes	I²C library routines require you to specify the module you want to use. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Write

Prototype	function I2Cx_Write(data_ : byte) : word;
Description	Sends data byte via the I²C bus.
Parameters	`data_:` data to be sent
Returns	`0` if there were no errors. `1` if write collision was detected on the I²C bus.
Requires	MCU with at least one I²C module. Used I²C module must be initialized before using this function. See I2Cx_Init routine. Also, START signal needs to be issued in order to use this function. See I2Cx_Start.
Example	var data_ : byte; error : word; ... error := I2C1_Write(data_); error := I2C1_Write(0xA3);
Notes	I²C library routines require you to specify the module you want to use. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Stop

Prototype	procedure I2Cx_Stop();
Description	Issues STOP signal.
Parameters	None.
Returns	Nothing.
Requires	MCU with at least one I²C module. Used I²C module must be initialized before using this function. See I2Cx_Init routine.
Example	// Issue STOP signal I2C1_Stop();
Notes	I²C library routines require you to specify the module you want to use. To select the desired I²C module, simply change the letter x in the routine prototype for a number from 1 to 3. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

Library Example

This code demonstrates working with the I²C library. Program sends data to EEPROM (data is written at the address 2). After that, program reads data from the same EEPROM address and displays it on PORTB for visual check. See the figure below how to interface the 24C02 to dsPIC30/33 and PIC24.

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program I2C_Simple;

  begin
    ADPCFG := 0xFFFF;       // initialize AN pins as digital

    LATB := 0;
    TRISB := 0;             // Configure PORTB as output

    I2C1_Init(100000);      // initialize I2C communication
    I2C1_Start();           // issue I2C start signal
    I2C1_Write(0xA2);       // send byte via I2C  (device address + W)
    I2C1_Write(2);          // send byte (address of EEPROM location)
    I2C1_Write(0xAA);       // send data (data to be written)
    I2C1_Stop();            // issue I2C stop signal

    Delay_100ms();

    I2C1_Start();           // issue I2C start signal
    I2C1_Write(0xA2);       // send byte via I2C  (device address + W)
    I2C1_Write(2);          // send byte (data address)
    I2C1_Restart();         // issue I2C signal repeated start
    I2C1_Write(0xA3);       // send byte (device address + R)
    PORTB := I2C1_Read(1);  // Read the data (NO acknowledge)
    I2C1_Stop();            // issue I2C stop signal
  end.

HW Connection

Interfacing 24c02 to dsPIC30/33 and PIC24 via I²C

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