mraa/api/i2c.h

/*
 * Author: Brendan Le Foll
 *
 * Copyright © 2014 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#pragma once

#include <stdio.h>
#include <fcntl.h>

#include "smbus.hpp"

namespace maa {

/** An I2C Master, used for communicating with I2C slave devices
 *
 * Example:
 * @code
 * // Read from I2C slave at address 0x62
 *
 * #include "maa.h"
 *
 * I2C i2c(p28, p27);
 *
 * int main() {
 *     int address = 0x62;
 *     char data[2];
 *     i2c.read(address, data, 2);
 * }
 * @endcode
 */
class I2C {

public:
    enum RxStatus {
        NoData,
        MasterGeneralCall,
        MasterWrite,
        MasterRead
    };

    enum Acknowledge {
        NoACK = 0,
        ACK   = 1
    };

    /** Create an I2C Master interface, connected to the specified pins
     *
     *  @param sda I2C data line pin
     *  @param scl I2C clock line pin
     */
    I2C(unsigned int sda, unsigned int scl);

    /** Set the frequency of the I2C interface
     *
     *  @param hz The bus frequency in hertz
     */
    void frequency(int hz);

    /** Read from an I2C slave
     *
     * Performs a complete read transaction. The bottom bit of
     * the address is forced to 1 to indicate a read.
     *
     *  @param address 8-bit I2C slave address [ addr | 1 ]
     *  @param data Pointer to the byte-array to read data in to
     *  @param length Number of bytes to read
     *  @param repeated Repeated start, true - don't send stop at end
     *
     *  @returns
     *       0 on success (ack),
     *   non-0 on failure (nack)
     */
    int read(int address, char *data, int length, bool repeated = false);

    /** Read a single byte from the I2C bus
     *
     *  @param ack indicates if the byte is to be acknowledged (1 = acknowledge)
     *
     *  @returns
     *    the byte read
     */
    int read(int ack);

    /** Write to an I2C slave
     *
     * Performs a complete write transaction. The bottom bit of
     * the address is forced to 0 to indicate a write.
     *
     *  @param address 8-bit I2C slave address [ addr | 0 ]
     *  @param data Pointer to the byte-array data to send
     *  @param length Number of bytes to send
     *  @param repeated Repeated start, true - do not send stop at end
     *
     *  @returns
     *       0 on success (ack),
     *   non-0 on failure (nack)
     */
    int write(int address, const char *data, int length, bool repeated = false);

    /** Write single byte out on the I2C bus
     *  @param data data to write out on bus
     *
     *  @returns
     *    '1' if an ACK was received,
     *    '0' otherwise
     */
    int write(int data);

    /** Creates a start condition on the I2C bus
     */
    void start(void);

    /** Creates a stop condition on the I2C bus
     */
    void stop(void);

protected:
    void aquire();
    int _hz;
    int i2c_handle;
};
}