svn / mbed / trunk / I2CSlave.h

/* mbed Microcontroller Library - I2CSlave
 * Copyright (c) 2007-2011 ARM Limited. All rights reserved.
 */ 
 
#ifndef MBED_I2C_SLAVE_H
#define MBED_I2C_SLAVE_H

#include "device.h"

#if DEVICE_I2CSLAVE

#include "platform.h"
#include "PinNames.h"
#include "PeripheralNames.h"
#include "Base.h"

namespace mbed {

/* Class: I2CSlave
 *  An I2C Slave, used for communicating with an I2C Master device
 *
 * Example:
 * > // Simple I2C responder
 * > #include <mbed.h>
 * >
 * > I2CSlave slave(p9, p10);
 * >
 * > int main() {
 * >     char buf[10];
 * >     char msg[] = "Slave!";
 * >
 * >     slave.address(0xA0);
 * >     while (1) {
 * >         int i = slave.receive();
 * >         switch (i) {
 * >             case I2CSlave::ReadAddressed: 
 * >                 slave.write(msg, strlen(msg) + 1); // Includes null char
 * >                 break;
 * >             case I2CSlave::WriteGeneral:
 * >                 slave.read(buf, 10);
 * >                 printf("Read G: %s\n", buf);
 * >                 break;
 * >             case I2CSlave::WriteAddressed:
 * >                 slave.read(buf, 10);
 * >                 printf("Read A: %s\n", buf);
 * >                 break;
 * >         }
 * >         for(int i = 0; i < 10; i++) buf[i] = 0;    // Clear buffer
 * >     }
 * > }
 * >                  
 */
class I2CSlave : public Base {

public:
    
    enum RxStatus {
        NoData              = 0
        , ReadAddressed     = 1
        , WriteGeneral      = 2
        , WriteAddressed    = 3
    };

    /* Constructor: I2CSlave
     *  Create an I2C Slave interface, connected to the specified pins.
     *
     * Variables:
     *  sda - I2C data line pin
     *  scl - I2C clock line pin
     */
    I2CSlave(PinName sda, PinName scl, const char *name = NULL);

    /* Function: frequency
     *  Set the frequency of the I2C interface
     *
     * Variables:
     *  hz - The bus frequency in hertz
     */
    void frequency(int hz);

    /* Function: receive
     *  Checks to see if this I2C Slave has been addressed.
     *
     * Variables:
     *  returns - a status indicating if the device has been addressed, and how
     *  > NoData            - the slave has not been addressed
     *  > ReadAddressed     - the master has requested a read from this slave
     *  > WriteAddressed    - the master is writing to this slave
     *  > WriteGeneral      - the master is writing to all slave 
     */
    int receive(void);

    /* Function: read
     *  Read from an I2C master.
     *
     * Variables:
     *  data - pointer to the byte array to read data in to
     *  length - maximum number of bytes to read
     *  returns - 0 on success, non-0 otherwise
     */
    int read(char *data, int length); 

    /* Function: read
     *  Read a single byte from an I2C master.
     *
     * Variables:
     *  returns - the byte read
     */
    int read(void);

    /* Function: write
     *  Write to an I2C master.
     *
     * Variables:
     *  data - pointer to the byte array to be transmitted
     *  length - the number of bytes to transmite
     *  returns - a 0 on success, non-0 otherwise
     */
    int write(const char *data, int length);

    /* Function: write
     *  Write a single byte to an I2C master.
     *
     * Variables
     *  data - the byte to write
     *  returns - a '1' if an ACK was received, a '0' otherwise
     */
    int write(int data);

    /* Function: address
     *  Sets the I2C slave address.
     *
     * Variables
     *  address - the address to set for the slave (ignoring the least
     *  signifcant bit). If set to 0, the slave will only respond to the
     *  general call address.
     */
    void address(int address);

    /* Function: stop
     *  Reset the I2C slave back into the known ready receiving state.
     */
    void stop(void);

protected:

    I2CName     _i2c;
};

} // namespace mbed

#endif

#endif