I²C Library
The I²C full master I²C module is available with a number of the PIC32 MCU models. The mikroC PRO for PIC32 provides a library which supports the master I²C mode.
- 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 5.
- Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.
Library Routines
I2Cx_Init
Prototype |
void I2Cx_Init(unsigned long scl); |
---|---|
Description |
This function 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 :
As per the I²C standard, SCL clock may be 100 kHz or 400 kHz. However, the user can specify any clock rate up to 1 MHz. |
Parameters |
|
Returns |
Nothing. |
Requires |
MCU with the I²C module. |
Example |
// Initialize the I2C1 module with clock_rate of 100000 I2C1_Init(100000); |
Notes |
|
I2Cx_Init_Advanced
Prototype |
void I2Cx_Init_Advanced(unsigned long Fclk_Khz, unsigned long scl); |
---|---|
Description |
This function configures and initializes the desired I²C module using Peripheral Bus Clock and default initialization settings. As per the I²C standard, SCL clock may be 100 kHz or 400 kHz. However, the user can specify any clock rate up to 1 MHz. |
Parameters |
|
Returns |
Nothing. |
Requires |
MCU with the I²C module. |
Example |
I2C1_Init_Advanced(50000, 100000); |
Notes |
|
I2Cx_Start
Prototype |
unsigned I2Cx_Start(); |
---|---|
Description |
Determines if the I²C bus is free and issues START signal. |
Parameters |
None. |
Returns |
|
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 |
|
I2Cx_Restart
Prototype |
unsigned I2Cx_Restart(); |
---|---|
Description |
Issues repeated START signal. |
Parameters |
None. |
Returns |
|
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 |
|
I2Cx_Is_Idle
Prototype |
unsigned I2Cx_Is_Idle(); |
---|---|
Description |
Waits for the I²C bus to become free. This is a blocking function. |
Parameters |
None. |
Returns |
|
Requires |
MCU with at least one I²C module. Used I²C module must be initialized before using this function. See I2Cx_Init routine. |
Example |
unsigned char data_; ... if !(I2C1_Is_Idle) I2C1_Write(data_); ... |
Notes |
|
I2Cx_Read
Prototype |
unsigned char I2Cx_Read(unsigned ack); |
---|---|
Description |
Reads a byte from the I²C bus. |
Parameters |
|
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 |
unsigned char take; ... // Read data and send the not_acknowledge signal take = I2C1_Read(_I2C_NACK); |
Notes |
|
I2Cx_Write
Prototype |
unsigned I2Cx_Write(unsigned char data_); |
---|---|
Description |
Sends data byte via the I²C bus. |
Parameters |
|
Returns |
|
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 |
unsigned char data_; unsigned error; ... error = I2C1_Write(data_); error = I2C1_Write(0xA3); |
Notes |
|
I2Cx_Stop
Prototype |
void 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 |
|
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 PIC32.
void EEPROM_24C02_Init() {
I2C2_Init(100000);
}
//--------------- Writes data to 24C02 EEPROM - signle location
void EEPROM_24C02_WrSingle(unsigned short wAddr, unsigned short wData) {
I2C2_Start(); // issue I2C start signal
I2C2_Write(0xA0); // send byte via I2C (command to 24cO2)
I2C2_Write(wAddr); // send byte (address of EEPROM location)
I2C2_Write(wData); // send data (data to be written)
I2C2_Stop();
}
//--------------- Reads data from 24C02 EEPROM - single location (random)
unsigned short EEPROM_24C02_RdSingle(unsigned short rAddr) {
unsigned short reslt;
I2C2_Start(); // issue I2C start signal
I2C2_Write(0xA0); // send byte via I2C (device address + W)
I2C2_Write(rAddr); // send byte (data address)
I2C2_Restart(); // issue I2C signal repeated start
I2C2_Write(0xA1); // send byte (device address + R)
reslt = I2C2_Read(1); // Read the data (NO acknowledge)
I2C2_Stop();
return reslt;
}
unsigned short i;
char b;
void main(){
CHECON = 0x30;
AD1PCFG = 0xFFFFFFFF;
LATB = 0; // Set PORTB value to zero
TRISB = 0; // Configure PORTB as output
TRISD = 0; // Configure PORTB as output
LATD = 0; // Set PORTD value to zero
EEPROM_24C02_Init(); // performs I2C initialization
b = 0x00;
for(i = 0x00; i<0x80; i++) {
EEPROM_24C02_WrSingle(i,b);
b++;
delay_ms(5);
}
for(i = 0x00; i < 0x80; i++){
LATD = i;
LATB = EEPROM_24C02_RdSingle(i);
delay_ms(100);
}
}
What do you think about this topic ? Send us feedback!