net/i2c.h File Reference

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Detailed Description

I2C Functions.

Author:

Modtronix Engineering

Compiler:

MPLAB C18 v2.10 or higher
HITECH PICC-18 V8.35PL3 or higher

Description

This module contains code for reading and writing devices on the I2C bus.

#define	I2C_MASTER   8
#define	I2C_SLAVE_10   7
#define	I2C_SLAVE_7   6
#define	I2C_SLEW_OFF   0xC0
#define	I2C_SLEW_ON   0x00
Defines
#define	i2cBusCollision()   PIR2_BCLIF
#define	i2cClose()   (SSPCON1 &= 0xDF)
#define	i2cDataRdy()   (SSPSTAT_BF)
#define	i2cIsIdle()   (((SSPCON2 & 0x1F) | (SSPSTAT_R_W)) ? FALSE : TRUE)
#define	i2cPutAck()   {SSPCON2_ACKDT=0; SSPCON2_ACKEN=1;}
#define	i2cPutNack()   {SSPCON2_ACKDT=1; SSPCON2_ACKEN=1;}
#define	i2cPutStart()   (SSPCON2_SEN=1)
#define	i2cPutStartAndWait()   {SSPCON2_SEN=1; while ( SSPCON2_SEN );}
#define	i2cPutStop()   (SSPCON2_PEN=1)
#define	i2cPutStopAndWait()   {SSPCON2_PEN=1; while(SSPCON2_PEN);}
#define	i2cRestart()   (SSPCON2_RSEN=1)
#define	i2cWaitForIdle()   while ((SSPCON2 & 0x1F) | (SSPSTAT_R_W))
#define	i2cWasAckReceived()   (!SSPCON2_ACKSTAT)
#define	SSPENB   0x20
Functions
unsigned char	i2cGetByte (void)
void	i2cOpen (unsigned char mode, unsigned char slew, unsigned char baud)
unsigned char	i2cPutByte (unsigned char data_out)

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Define Documentation

#define I2C_MASTER   8

#define I2C_SLAVE_10   7

#define I2C_SLAVE_7   6

The following defines are used for the mode parameter in the i2cOpen() function:

• I2C_SLAVE_7 I2C Slave mode, 7-bit address
• I2C_SLAVE_10 I2C Slave mode, 10-bit address
• I2C_MASTER I2C Master mode

#define I2C_SLEW_OFF   0xC0

The following defines are used for the slew parameter in the i2cOpen() function:

• I2C_SLEW_OFF Slew rate disabled for 100kHz mode
• I2C_SLEW_ON Slew rate enabled for 400kHz mode

#define I2C_SLEW_ON   0x00

 

#define i2cBusCollision

(

)

PIR2_BCLIF

Test if a bus collision has occured. Return TRUE if it did, else FALSE

 

#define i2cClose

(

)

(SSPCON1 &= 0xDF)

Disable I2C module

 

#define i2cDataRdy

(

)

(SSPSTAT_BF)

Checks if the SSP buffer contains any data that can be read.

Example:

  if (i2cDataRdy())
  {
      var = i2cGetByte();
  }

Returns:

1 if there is data in the SSP buffer 0 if there is no data in the SSP buffer

 

#define i2cIsIdle

(

)

(((SSPCON2 & 0x1F) | (SSPSTAT_R_W)) ? FALSE : TRUE)

Checks if the I2C bus is IDLE, and available to be used. The i2cIsIdle() function is required since the hardware I2C peripheral does not allow for spooling of bus sequences. The I2C peripheral must be in an IDLE state before an I2C operation can be initiated or a write collision will be generated.

Returns:

TRUE if I2C bus is idle and can be used
FALSE if I2C bus is NOT idle. User has to wait until bus is idle before using it.

 

#define i2cPutAck

(

)

{SSPCON2_ACKDT=0; SSPCON2_ACKEN=1;}

Generate bus ACK condition

 

#define i2cPutNack

(

)

{SSPCON2_ACKDT=1; SSPCON2_ACKEN=1;}

Generate bus Not ACK condition.

 

#define i2cPutStart

(

)

(SSPCON2_SEN=1)

Generate bus start condition

 

#define i2cPutStartAndWait

(

)

{SSPCON2_SEN=1; while ( SSPCON2_SEN );}

Generate bus start condition, and waits until it is finished

 

#define i2cPutStop

(

)

(SSPCON2_PEN=1)

Generate bus stop condition

 

#define i2cPutStopAndWait

(

)

{SSPCON2_PEN=1; while(SSPCON2_PEN);}

Generate bus stop condition, and waits until it is finished

 

#define i2cRestart

(

)

(SSPCON2_RSEN=1)

Generate bus restart condition

 

#define i2cWaitForIdle

(

)

while ((SSPCON2 & 0x1F) | (SSPSTAT_R_W))

Waits until the I2C bus is IDLE, and available to be used. The i2cWaitForIdle() function is required since the hardware I2C peripheral does not allow for spooling of bus sequences. The I2C peripheral must be in an IDLE state before an I2C operation can be initiated or a write collision will be generated.

 

#define i2cWasAckReceived

(

)

(!SSPCON2_ACKSTAT)

Tests if an ACK was received from the slave. Returns true if it was, else false.

#define SSPENB   0x20

Enable serial port and configures SCK, SDO, SDI

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Function Documentation

unsigned char i2cGetByte

(

void

)

Read single byte from I2C bus

Returns:

Contents of SSPBUF register

void i2cOpen	(	unsigned char	mode,
		unsigned char	slew,
		unsigned char	baud
	)

This function resets the SSP module to the POR state and then configures the module for Master/Slave mode and the selected slew rate.

Parameters:

	mode	One of the following values defined in i2c.h: I2C_SLAVE_7 I2C Slave mode, 7-bit address I2C_SLAVE_10 I2C Slave mode, 10-bit address I2C_MASTER I2C Master mode
	slew	One of the following values, defined in i2c.h: I2C_SLEW_OFF Slew rate disabled for 100 kHz mode I2C_SLEW_ON Slew rate enabled for 400 kHz mode
	baud	The baud rate of the I2C unit when configured for I2C Master mode. This is the value that will be assigned to the SSPADD register. It is calculated as follows: SSPADD = ( ((CLOCK_FREQ / BAUD) / 4) - 1 ) For example, if the CPU clock frequency is 40MHz and we need a I2C baud rate of 400KHz: SSPADD = ( ((40,000,000/400,000) / 4) - 1 ) = 24 Some common values for SSPADD are: 400 KHz at 40 MHz system clock = 24 400 KHz at 20 MHz system clock = 12 400 KHz at 10 MHz system clock = 5

unsigned char i2cPutByte

(

unsigned char

data_out

)

This routine writes a single byte to the I2C bus.

Parameters:

data_out

Single data byte for I2C bus

Returns:

Status byte for WCOL detection.
Returns 0 if OK, else 1 if error

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