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/platform.h"
00020 
00021 #if defined (DEVICE_I2CSLAVE) || defined(DOXYGEN_ONLY)
00022 
00023 #include "hal/i2c_api.h"
00024 
00025 namespace mbed {
00026 /** \addtogroup drivers */
00027 
00028 /** An I2C Slave, used for communicating with an I2C Master device.
00029  *
00030  * @note Synchronization level: Not protected
00031  *
00032  * Example Simple I2C responder:
00033  * @code
00034  * #include <mbed.h>
00035  *
00036  * const int SLAVE_ADDRESS = 0xA0;
00037  * const char message[] = "Slave!";
00038  *
00039  * I2CSlave slave(I2C_SDA, I2C_SCL);
00040  *
00041  * int main() {
00042  *     slave.address(SLAVE_ADDRESS);
00043  *     while (1) {
00044  *         int operation = slave.receive();
00045  *         switch (operation) {
00046  *             case I2CSlave::ReadAddressed:
00047  *                 int status = slave.write(message, sizeof(message));
00048  *                 if (status == 0) {
00049  *                     printf("Written message: %s\n", message);
00050  *                 } else {
00051  *                     printf("Failed to write message.\n");
00052  *                 }
00053  *                 break;
00054  *             case I2CSlave::WriteGeneral:
00055  *                 int byte_read = slave.read();
00056  *                 printf("Read General: %c (%d)\n", byte_read, byte_read);
00057  *                 break;
00058  *             case I2CSlave::WriteAddressed:
00059  *                 int byte_read = slave.read();
00060  *                 printf("Read Addressed: %c (%d)\n", byte_read, byte_read);
00061  *                 break;
00062  *         }
00063  *     }
00064  * }
00065  * @endcode
00066  * @ingroup drivers
00067  */
00068 class I2CSlave {
00069 
00070 public:
00071     enum RxStatus {
00072         NoData         = 0,
00073         ReadAddressed  = 1,
00074         WriteGeneral   = 2,
00075         WriteAddressed = 3
00076     };
00077 
00078     /** Create an I2C Slave interface, connected to the specified pins.
00079      *
00080      *  @param sda I2C data line pin.
00081      *  @param scl I2C clock line pin.
00082      */
00083     I2CSlave(PinName sda, PinName scl);
00084 
00085     /** Set the frequency of the I2C interface.
00086      *
00087      *  @param hz The bus frequency in Hertz.
00088      */
00089     void frequency(int hz);
00090 
00091     /** Check if this I2C Slave has been addressed.
00092      *
00093      *  @return A status indicating if the device has been addressed and how.
00094      *  @retval NoData          The slave has not been addressed.
00095      *  @retval ReadAddressed   The master has requested a read from this slave.
00096      *  @retval WriteAddressed  The master is writing to this slave.
00097      *  @retval WriteGeneral    The master is writing to all slave.
00098      */
00099     int receive(void);
00100 
00101     /** Read specified number of bytes from an I2C master.
00102      *
00103      *  @param data   Pointer to the buffer to read data into.
00104      *  @param length Number of bytes to read.
00105      *
00106      *  @return Result of the operation.
00107      *  @retval 0       If the number of bytes read is equal to length requested.
00108      *  @retval nonzero On error or if the number of bytes read is less than requested.
00109      */
00110     int read(char *data, int length);
00111 
00112     /** Read a single byte from an I2C master.
00113      *
00114      *  @return The byte read.
00115      */
00116     int read(void);
00117 
00118     /** Write to an I2C master.
00119      *
00120      *  @param data   Pointer to the buffer containing the data to be sent.
00121      *  @param length Number of bytes to send.
00122      *
00123      *  @return
00124      *  @retval 0       If written all bytes successfully.
00125      *  @retval nonzero On error or if the number of bytes written is less than requested.
00126      */
00127     int write(const char *data, int length);
00128 
00129     /** Write a single byte to an I2C master.
00130      *
00131      *  @param data Value to write.
00132      *
00133      *  @return Result of the operation.
00134      *  @retval 0 If a NACK is received.
00135      *  @retval 1 If an ACK is received.
00136      *  @retval 2 On timeout.
00137      */
00138     int write(int data);
00139 
00140     /** Set the I2C slave address.
00141      *
00142      *  @param address The address to set for the slave (least significant bit is ignored).
00143      *
00144      *  @note If address is set to 0, the slave will only respond to the
00145      *  general call address.
00146      */
00147     void address(int address);
00148 
00149     /** Reset the I2C slave back into the known ready receiving state.
00150      */
00151     void stop(void);
00152 
00153 #if !defined(DOXYGEN_ONLY)
00154 
00155 protected:
00156     /* Internal i2c object identifying the resources */
00157     i2c_t _i2c;
00158 
00159 #endif //!defined(DOXYGEN_ONLY)
00160 };
00161 
00162 } // namespace mbed
00163 
00164 #endif
00165 
00166 #endif