exploringBB::I2CDevice Class Reference

Generic I2C Device class that can be used to connect to any type of I2C device and read or write to its registers. More...

#include <I2CDevice.h>

Inheritance diagram for exploringBB::I2CDevice:

Collaboration diagram for exploringBB::I2CDevice:

Public Member Functions
	I2CDevice (unsigned int bus, unsigned int device)
virtual int	open ()
virtual int	write (unsigned char value)
virtual unsigned char	readRegister (unsigned int registerAddress)
virtual unsigned char *	readRegisters (unsigned int number, unsigned int fromAddress=0)
virtual int	writeRegister (unsigned int registerAddress, unsigned char value)
virtual void	debugDumpRegisters (unsigned int number=0xff)
virtual void	close ()
virtual	~I2CDevice ()
Public Member Functions inherited from exploringBB::BusDevice
	BusDevice (unsigned int bus, unsigned int device)
virtual	~BusDevice ()

Additional Inherited Members
Protected Attributes inherited from exploringBB::BusDevice
unsigned int	bus
unsigned int	device
int	file

Detailed Description

Generic I2C Device class that can be used to connect to any type of I2C device and read or write to its registers.

Constructor & Destructor Documentation

exploringBB::I2CDevice::I2CDevice	(	unsigned int	bus,
		unsigned int	device
	)

Constructor for the I2CDevice class. It requires the bus number and device number. The constructor opens a file handle to the I2C device, which is destroyed when the destructor is called

Parameters

bus	The bus number. Usually 0 or 1 on the BBB
device	The device ID on the bus.

                                                         :
        BusDevice(bus,device){
        this->open();
}

exploringBB::I2CDevice::~I2CDevice ( )

virtual

Closes the file on destruction, provided that it has not already been closed.

                      {
        if(file!=-1) this->close();
}

Member Function Documentation

void exploringBB::I2CDevice::close ( )

virtual

Close the file handles and sets a temporary state to -1.

Implements exploringBB::BusDevice.

                     {
        ::close(this->file);
        this->file = -1;
}

void exploringBB::I2CDevice::debugDumpRegisters ( unsigned int  number = 0xff )

virtual

Method to dump the registers to the standard output. It inserts a return character after every 16 values and displays the results in hexadecimal to give a standard output using the HEX() macro that is defined at the top of this file. The standard output will stay in hexadecimal format, hence the call on the last like.

Parameters

number

the total number of registers to dump, defaults to 0xff

Implements exploringBB::BusDevice.

                                                     {
        cout << "Dumping Registers for Debug Purposes:" << endl;
        unsigned char *registers = this->readRegisters(number);
        for(int i=0; i<(int)number; i++){
                cout << HEX(*(registers+i)) << " ";
                if (i%16==15) cout << endl;
        }
        cout << dec;
}

int exploringBB::I2CDevice::open ( )

virtual

Open a connection to an I2C device

Returns

1 on failure to open to the bus or device, 0 on success.

Implements exploringBB::BusDevice.

                   {
   string name;
   if(this->bus==0) name = BBB_I2C_0;
   else name = BBB_I2C_1;

   if((this->file=::open(name.c_str(), O_RDWR)) < 0){
      perror("I2C: failed to open the bus\n");
          return 1;
   }
   if(ioctl(this->file, I2C_SLAVE, this->device) < 0){
      perror("I2C: Failed to connect to the device\n");
          return 1;
   }
   return 0;
}

unsigned char exploringBB::I2CDevice::readRegister ( unsigned int  registerAddress )

virtual

Read a single register value from the address on the device.

Parameters

registerAddress

the address to read from

Returns

the byte value at the register address.

Implements exploringBB::BusDevice.

                                                                 {
   this->write(registerAddress);
   unsigned char buffer[1];
   if(::read(this->file, buffer, 1)!=1){
      perror("I2C: Failed to read in the value.\n");
      return 1;
   }
   return buffer[0];
}

unsigned char * exploringBB::I2CDevice::readRegisters ( unsigned int  number, unsigned int  fromAddress = 0  )

virtual

Method to read a number of registers from a single device. This is much more efficient than reading the registers individually. The from address is the starting address to read from, which defaults to 0x00.

Parameters

number	the number of registers to read from the device
fromAddress	the starting address to read from

Returns

a pointer of type unsigned char* that points to the first element in the block of registers

Implements exploringBB::BusDevice.

                                                                                    {
        this->write(fromAddress);
        unsigned char* data = new unsigned char[number];
    if(::read(this->file, data, number)!=(int)number){
       perror("IC2: Failed to read in the full buffer.\n");
           return NULL;
    }
        return data;
}

int exploringBB::I2CDevice::write ( unsigned char  value )

virtual

Write a single value to the I2C device. Used to set up the device to read from a particular address.

Parameters

value

the value to write to the device

Returns

1 on failure to write, 0 on success.

Implements exploringBB::BusDevice.

                                       {
   unsigned char buffer[1];
   buffer[0]=value;
   if (::write(this->file, buffer, 1)!=1){
      perror("I2C: Failed to write to the device\n");
      return 1;
   }
   return 0;
}

int exploringBB::I2CDevice::writeRegister ( unsigned int  registerAddress, unsigned char  value  )

virtual

Write a single byte value to a single register.

Parameters

registerAddress	The register address
value	The value to be written to the register

Returns

1 on failure to write, 0 on success.

Implements exploringBB::BusDevice.

                                                                             {
   unsigned char buffer[2];
   buffer[0] = registerAddress;
   buffer[1] = value;
   if(::write(this->file, buffer, 2)!=2){
      perror("I2C: Failed write to the device\n");
      return 1;
   }
   return 0;
}

---

The documentation for this class was generated from the following files:

• /home/molloyd/exploringBB/library/bus/I2CDevice.h
• /home/molloyd/exploringBB/library/bus/I2CDevice.cpp