I2CSlave.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 #ifndef MBED_I2C_SLAVE_H
00017 #define MBED_I2C_SLAVE_H
00018 
00019 #include "platform.h"
00020 
00021 #if DEVICE_I2CSLAVE
00022 
00023 #include "i2c_api.h"
00024 
00025 namespace mbed {
00026 
00027 /** An I2C Slave, used for communicating with an I2C Master device
00028  *
00029  * Example:
00030  * @code
00031  * // Simple I2C responder
00032  * #include <mbed.h>
00033  *
00034  * I2CSlave slave(p9, p10);
00035  *
00036  * int main() {
00037  *     char buf[10];
00038  *     char msg[] = "Slave!";
00039  *
00040  *     slave.address(0xA0);
00041  *     while (1) {
00042  *         int i = slave.receive();
00043  *         switch (i) {
00044  *             case I2CSlave::ReadAddressed:
00045  *                 slave.write(msg, strlen(msg) + 1); // Includes null char
00046  *                 break;
00047  *             case I2CSlave::WriteGeneral:
00048  *                 slave.read(buf, 10);
00049  *                 printf("Read G: %s\n", buf);
00050  *                 break;
00051  *             case I2CSlave::WriteAddressed:
00052  *                 slave.read(buf, 10);
00053  *                 printf("Read A: %s\n", buf);
00054  *                 break;
00055  *         }
00056  *         for(int i = 0; i < 10; i++) buf[i] = 0;    // Clear buffer
00057  *     }
00058  * }
00059  * @endcode
00060  */
00061 class I2CSlave {
00062 
00063 public:
00064     enum RxStatus {
00065         NoData         = 0,
00066         ReadAddressed  = 1,
00067         WriteGeneral   = 2,
00068         WriteAddressed = 3
00069     };
00070 
00071     /** Create an I2C Slave interface, connected to the specified pins.
00072      *
00073      *  @param sda I2C data line pin
00074      *  @param scl I2C clock line pin
00075      */
00076     I2CSlave(PinName sda, PinName scl);
00077 
00078     /** Set the frequency of the I2C interface
00079      *
00080      *  @param hz The bus frequency in hertz
00081      */
00082     void frequency(int hz);
00083 
00084     /** Checks to see if this I2C Slave has been addressed.
00085      *
00086      *  @returns
00087      *  A status indicating if the device has been addressed, and how
00088      *  - NoData            - the slave has not been addressed
00089      *  - ReadAddressed     - the master has requested a read from this slave
00090      *  - WriteAddressed    - the master is writing to this slave
00091      *  - WriteGeneral      - the master is writing to all slave
00092      */
00093     int receive(void);
00094 
00095     /** Read from an I2C master.
00096      *
00097      *  @param data pointer to the byte array to read data in to
00098      *  @param length maximum number of bytes to read
00099      *
00100      *  @returns
00101      *       0 on success,
00102      *   non-0 otherwise
00103      */
00104     int read(char *data, int length);
00105 
00106     /** Read a single byte from an I2C master.
00107      *
00108      *  @returns
00109      *    the byte read
00110      */
00111     int read(void);
00112 
00113     /** Write to an I2C master.
00114      *
00115      *  @param data pointer to the byte array to be transmitted
00116      *  @param length the number of bytes to transmite
00117      *
00118      *  @returns
00119      *       0 on success,
00120      *   non-0 otherwise
00121      */
00122     int write(const char *data, int length);
00123 
00124     /** Write a single byte to an I2C master.
00125      *
00126      *  @data the byte to write
00127      *
00128      *  @returns
00129      *    '1' if an ACK was received,
00130      *    '0' otherwise
00131      */
00132     int write(int data);
00133 
00134     /** Sets the I2C slave address.
00135      *
00136      *  @param address The address to set for the slave (ignoring the least
00137      *  signifcant bit). If set to 0, the slave will only respond to the
00138      *  general call address.
00139      */
00140     void address(int address);
00141 
00142     /** Reset the I2C slave back into the known ready receiving state.
00143      */
00144     void stop(void);
00145 
00146 protected:
00147     i2c_t _i2c;
00148 };
00149 
00150 } // namespace mbed
00151 
00152 #endif
00153 
00154 #endif