I2C Library

I²C Library

The I²C full master I²C module is available with a number of the PIC32 MCU models. The mikroBasic PRO for PIC32 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 5.
Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Init

Prototype	sub procedure I2Cx_Init(dim scl as longint)
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 : Continue operation in IDLE mode. 7-bit slave address. Slew rate control enabled for High Speed mode (400 kHz). General call address disabled. SCL clock stretching disabled. 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	`scl:` requested serial clock rate.
Returns	Nothing.
Requires	MCU with the I²C module.
Example	' Initialize the I2C1 module with clock_rate=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 5. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Init_Advanced

Prototype	sub procedure I2Cx_Init_Advanced(dim Fclk_Khz, scl as longword)
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	`Fclk_Khz:` Peripheral Bus Clock frequency in kHz. `scl:` requested serial clock rate.
Returns	Nothing.
Requires	MCU with the I²C module.
Example	I2C1_Init_Advanced(50000, 100000)
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 5. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Start

Prototype	sub function I2Cx_Start() as word
Description	Determines if the I²C bus is free and issues START signal.
Parameters	None.
Returns	`0` if I²C bus was successfully started. `0xFFFF` if I²C bus was not successfully started.
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 5. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Restart

Prototype	sub function I2Cx_Restart() as word
Description	Issues repeated START signal.
Parameters	None.
Returns	`0` if I²C bus was successfully restarted. `0xFFFF` if I²C bus was not successfully restarted.
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 5. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Is_Idle

Prototype	sub function I2Cx_Is_Idle() as 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	dim data_ as byte ... if I2C1_Is_Idle() then I2C1_Write(data_) end if ...
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 5. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Read

Prototype	sub function I2Cx_Read(dim ack as word) as byte
Description	Reads a byte from the I²C bus.
Parameters	`ack:` acknowledge signal parameter. If this parameter is `_I2C_ACK`, acknowledge signal will be sent after reading, if its value is `_I2C_NACK`, not acknowledge signal will be sent after reading.
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	dim take as byte ... ' Read data and send the not_acknowledge signal take = I2C1_Read(_I2C_NACK)
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 5. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Write

Prototype	sub function I2Cx_Write(dim data_ as byte) as 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	dim data_ as byte error as 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 5. Number of I²C modules per MCU differs from chip to chip. Please, read the appropriate datasheet before utilizing this library.

I2Cx_Stop

Prototype	sub 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 5. 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 PIC32.

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program I2C_Simple

main:
program I2C_Simple

dim i, b as char

sub procedure EEPROM_24C02_Init()
  I2C2_Init(100000)
end sub

'--------------- Writes data to 24C02 EEPROM - signle location
sub procedure EEPROM_24C02_WrSingle(dim wAddr as byte, dim wData as byte)
  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()
end sub

'--------------- Reads data from 24C02 EEPROM - single location (random)
sub function EEPROM_24C02_RdSingle(dim rAddr as byte) as byte
  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)
  result = I2C2_Read(1)     ' Read the data (NO acknowledge)
  I2C2_Stop()
end sub

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 PORTB value to zero

  EEPROM_24C02_Init()                      ' performs I2C initialization
  b = 0x00
  for i = 0x00 to 0x80
    EEPROM_24C02_WrSingle(i,b)
    Inc(b)
    Delay_ms(5)
  next i

  for i = 0x00 to 0x80
    LATD = i
    LATB = EEPROM_24C02_RdSingle(i)
    Delay_ms(100)
  next i
end.

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