I²C Library
I²C Library
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
1in the prototype with the appropriate module number, i.e.I2C2_Init(100000);
Library Routines
I2C1_Init
| Prototype |
|
|---|---|
| Returns |
Nothing. |
| Description |
Initializes I²C with desired 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_Start
| Prototype |
|
|---|---|
| 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. See I2C1_Init. |
| Example |
|
I2C1_Repeated_Start
| Prototype |
|
|---|---|
| Returns |
Nothing. |
| Description |
Issues repeated START signal. |
| Requires |
I²C must be configured before using this function. See I2C1_Init. |
| Example |
|
I2C1_Is_Idle
| Prototype |
|
|---|---|
| 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. See I2C1_Init. |
| Example |
|
I2C1_Rd
| Prototype |
|
|---|---|
| Returns |
Returns one byte from the slave. |
| Description |
Reads one byte from the slave, and sends not acknowledge signal if parameter |
| Requires |
I²C must be configured before using this function. See I2C1_Init. Also, START signal needs to be issued in order to use this function. See I2C1_Start. |
| Example |
|
I2C1_Wr
| Prototype |
|
|---|---|
| Returns |
Returns 0 if there were no errors. |
| Description |
Sends data byte (parameter |
| Requires |
I²C must be configured before using this function. See I2C1_Init. Also, START signal needs to be issued in order to use this function. See I2C1_Start. |
| Example |
|
I2C1_Stop
| Prototype |
|
|---|---|
| Returns |
Nothing. |
| Description |
Issues STOP signal. |
| Requires |
I²C must be configured before using this function. See I2C1_Init. |
| Example |
|
Library 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).
void main(){
ANSEL = 0; // Configure AN pins as digital I/O
ANSELH = 0;
PORTB = 0;
TRISB = 0; // Configure PORTB as output
I2C1_Init(100000); // initialize I2C communication
I2C1_Start(); // issue I2C start signal
I2C1_Wr(0xA2); // send byte via I2C (device address + W)
I2C1_Wr(2); // send byte (address of EEPROM location)
I2C1_Wr(0xAA); // send data (data to be written)
I2C1_Stop(); // issue I2C stop signal
Delay_100ms();
I2C1_Start(); // issue I2C start signal
I2C1_Wr(0xA2); // send byte via I2C (device address + W)
I2C1_Wr(2); // send byte (data address)
I2C1_Repeated_Start(); // issue I2C signal repeated start
I2C1_Wr(0xA3); // send byte (device address + R)
PORTB = I2C1_Rd(0u); // Read the data (NO acknowledge)
I2C1_Stop(); // issue I2C stop signal
}
HW Connection
