I2CSlave.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00017  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
00020  * SOFTWARE.
00021  */
00022 #ifndef MBED_I2C_SLAVE_H
00023 #define MBED_I2C_SLAVE_H
00024 
00025 #include "platform.h"
00026 
00027 #if DEVICE_I2CSLAVE
00028 
00029 #include "i2c_api.h"
00030 
00031 namespace mbed {
00032 
00033 /** An I2C Slave, used for communicating with an I2C Master device
00034  *
00035  * Example:
00036  * @code
00037  * // Simple I2C responder
00038  * #include <mbed.h>
00039  *
00040  * I2CSlave slave(p9, p10);
00041  *
00042  * int main() {
00043  *     char buf[10];
00044  *     char msg[] = "Slave!";
00045  *
00046  *     slave.address(0xA0);
00047  *     while (1) {
00048  *         int i = slave.receive();
00049  *         switch (i) {
00050  *             case I2CSlave::ReadAddressed:
00051  *                 slave.write(msg, strlen(msg) + 1); // Includes null char
00052  *                 break;
00053  *             case I2CSlave::WriteGeneral:
00054  *                 slave.read(buf, 10);
00055  *                 printf("Read G: %s\n", buf);
00056  *                 break;
00057  *             case I2CSlave::WriteAddressed:
00058  *                 slave.read(buf, 10);
00059  *                 printf("Read A: %s\n", buf);
00060  *                 break;
00061  *         }
00062  *         for(int i = 0; i < 10; i++) buf[i] = 0;    // Clear buffer
00063  *     }
00064  * }
00065  * @endcode
00066  */
00067 class I2CSlave {
00068 
00069 public:
00070     enum RxStatus {
00071         NoData         = 0,
00072         ReadAddressed  = 1,
00073         WriteGeneral   = 2,
00074         WriteAddressed = 3
00075     };
00076 
00077     /** Create an I2C Slave interface, connected to the specified pins.
00078      *
00079      *  @param sda I2C data line pin
00080      *  @param scl I2C clock line pin
00081      */
00082     I2CSlave(PinName sda, PinName scl);
00083 
00084     /** Set the frequency of the I2C interface
00085      *
00086      *  @param hz The bus frequency in hertz
00087      */
00088     void frequency(int hz);
00089 
00090     /** Checks to see if this I2C Slave has been addressed.
00091      *
00092      *  @returns
00093      *  A status indicating if the device has been addressed, and how
00094      *  - NoData            - the slave has not been addressed
00095      *  - ReadAddressed     - the master has requested a read from this slave
00096      *  - WriteAddressed    - the master is writing to this slave
00097      *  - WriteGeneral      - the master is writing to all slave
00098      */
00099     int receive(void);
00100 
00101     /** Read from an I2C master.
00102      *
00103      *  @param data pointer to the byte array to read data in to
00104      *  @param length maximum number of bytes to read
00105      *
00106      *  @returns
00107      *       0 on success,
00108      *   non-0 otherwise
00109      */
00110     int read(char *data, int length);
00111 
00112     /** Read a single byte from an I2C master.
00113      *
00114      *  @returns
00115      *    the byte read
00116      */
00117     int read(void);
00118 
00119     /** Write to an I2C master.
00120      *
00121      *  @param data pointer to the byte array to be transmitted
00122      *  @param length the number of bytes to transmite
00123      *
00124      *  @returns
00125      *       0 on success,
00126      *   non-0 otherwise
00127      */
00128     int write(const char *data, int length);
00129 
00130     /** Write a single byte to an I2C master.
00131      *
00132      *  @data the byte to write
00133      *
00134      *  @returns
00135      *    '1' if an ACK was received,
00136      *    '0' otherwise
00137      */
00138     int write(int data);
00139 
00140     /** Sets the I2C slave address.
00141      *
00142      *  @param address The address to set for the slave (ignoring the least
00143      *  signifcant bit). If set to 0, the slave will only respond to the
00144      *  general call address.
00145      */
00146     void address(int address);
00147 
00148     /** Reset the I2C slave back into the known ready receiving state.
00149      */
00150     void stop(void);
00151 
00152 protected:
00153     i2c_t _i2c;
00154 };
00155 
00156 } // namespace mbed
00157 
00158 #endif
00159 
00160 #endif
00161