com.dalsemi.system
Class I2CPort

java.lang.Object
  |
  +--com.dalsemi.system.I2CPort

public class I2CPort

extends Object

Class allowing access to I2C bus.
This class uses the I2C protocol on one of two resources:

• P5.0(SCL) and P5.1(SDA)
  Max rate 250Kbit/s, Min rate 2.5Kbit/s dependant on clockDelay value.
• Any two memory mapped IO areas.
  Masks are required to select bit or bits within byte for SCL and SDA.
  Max rate 33Kbit/s, Min rate 2.5Kbit/s dependant on clockDelay value.

Field Summary

byte	clockDelay How long to wait between I2C edge transitions.
int	SCLAddress Memory mapped address of the I2C clock line.
byte	SCLMask Bit mask for clock line within byte at SCLAddress.
int	SDAAddress Memory mapped address of the I2C data line.
byte	SDAMask Bit mask for data line within byte at SDAAddress.
byte	slaveAddress I2C address of slave.
static byte	STRETCH0 When in memory map mode, use to set the number of memory bus cycles to 2.
static byte	STRETCH1 When in memory map mode, use to set the number of memory bus cycles to 3.
static byte	STRETCH10 When in memory map mode, use to set the number of memory bus cycles to 12.
static byte	STRETCH2 When in memory map mode, use to set the number of memory bus cycles to 4.
static byte	STRETCH3 When in memory map mode, use to set the number of memory bus cycles to 5.
static byte	STRETCH7 When in memory map mode, use to set the number of memory bus cycles to 9.
static byte	STRETCH8 When in memory map mode, use to set the number of memory bus cycles to 10.
static byte	STRETCH9 When in memory map mode, use to set the number of memory bus cycles to 11.
byte	stretchCycles Number of stretch memory cycles to use when accessing memory mapped IO.

Constructor Summary

I2CPort()
Use processor port pin P5.0 for SCL and P5.1 for SDA.

I2CPort(int SCLAddress, byte SCLMask, int SDAAddress, byte SDAMask)
Use memory mapped IO address for SCL and SDA pins.

Method Summary

int	getStretchCycles() Gets the number of stretch memory cycles to use when accessing memory mapped IO.
int	read(byte[] barr, int off, int len) Reads into the byte array from the current slave address
void	setAddress(byte address) Sets the I2C slave address.
void	setClockDelay(byte delay) Sets how long to wait between I2C edge transitions.
void	setStretchCycles(byte stretch) Sets the number of stretch memory cycles to use when accessing memory mapped IO.
int	write(byte[] barr, int off, int len) Writes the byte array to the current slave address

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

STRETCH0

public static final byte STRETCH0

When in memory map mode, use to set the number of memory bus cycles to 2.

STRETCH1

public static final byte STRETCH1

When in memory map mode, use to set the number of memory bus cycles to 3.

STRETCH2

public static final byte STRETCH2

When in memory map mode, use to set the number of memory bus cycles to 4.

STRETCH3

public static final byte STRETCH3

When in memory map mode, use to set the number of memory bus cycles to 5.

STRETCH7

public static final byte STRETCH7

When in memory map mode, use to set the number of memory bus cycles to 9.

STRETCH8

public static final byte STRETCH8

When in memory map mode, use to set the number of memory bus cycles to 10.

STRETCH9

public static final byte STRETCH9

When in memory map mode, use to set the number of memory bus cycles to 11.

STRETCH10

public static final byte STRETCH10

When in memory map mode, use to set the number of memory bus cycles to 12.

stretchCycles

public byte stretchCycles

Number of stretch memory cycles to use when accessing memory mapped IO. Valid values are:
STRETCH0
STRETCH1
STRETCH2
STRETCH3
STRETCH7
STRETCH8
STRETCH9
STRETCH10

slaveAddress

public byte slaveAddress

I2C address of slave. Right justified, least significant bit of this byte = least significant bit of I2C slave address.

clockDelay

public byte clockDelay

How long to wait between I2C edge transitions.
1 increment of clockDelay adds approximately 109 nanoseconds between edges.

SCLAddress

public int SCLAddress

Memory mapped address of the I2C clock line.

SCLMask

public byte SCLMask

Bit mask for clock line within byte at SCLAddress.

SDAAddress

public int SDAAddress

Memory mapped address of the I2C data line.

SDAMask

public byte SDAMask

Bit mask for data line within byte at SDAAddress.

Constructor Detail

I2CPort

public I2CPort()

Use processor port pin P5.0 for SCL and P5.1 for SDA.

I2CPort

public I2CPort(int SCLAddress,
               byte SCLMask,
               int SDAAddress,
               byte SDAMask)

Use memory mapped IO address for SCL and SDA pins.

Parameters:

SCLAddress - address of latch.

SCLMask - mask of bit or bits to use.

SDAAddress - address of latch.

SDAMask - mask of bit or bits to use.

Method Detail

setAddress

public void setAddress(byte address)

Sets the I2C slave address. This address will take effect on the next read or write. Right justified, least significant bit of this byte = least significant bit of I2C slave address.

Parameters:

address - address of I2C slave device.

setClockDelay

public void setClockDelay(byte delay)

Sets how long to wait between I2C edge transitions.
1 increment of clockDelay adds approximately 109 nanoseconds between edges.

Parameters:

delay - I2C Clock delay

setStretchCycles

public void setStretchCycles(byte stretch)
                      throws IllegalArgumentException

Sets the number of stretch memory cycles to use when accessing memory mapped IO. Valid values are:
STRETCH0
STRETCH1
STRETCH2
STRETCH3
STRETCH7
STRETCH8
STRETCH9
STRETCH10

Parameters:

stretch - stretch cycle value

Throws:

IllegalArgumentException - if stretch is out of range

getStretchCycles

public int getStretchCycles()

Gets the number of stretch memory cycles to use when accessing memory mapped IO.

Returns:

stretch cycle value

write

public int write(byte[] barr,
                 int off,
                 int len)
          throws IllegalAddressException

Writes the byte array to the current slave address

Parameters:

barr - array of bytes to send

off - starting offset to send

len - length of bytes to send

Returns:

0 on success, or -1 on error (No ACK from I2C device)

Throws:

IllegalAddressException - if SCLAddress or SDAAddress is out of range

read

public int read(byte[] barr,
                int off,
                int len)
         throws IllegalAddressException

Reads into the byte array from the current slave address

Parameters:

barr - array to fill from read operation

off - starting offset to read into

len - length of bytes to read

Returns:

0 on success, or -1 on error (No ACK from I2C device)

Throws:

IllegalAddressException - if SCLAddress or SDAAddress is out of range