I2CSlave.h

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 ARM Limited
00003  * SPDX-License-Identifier: Apache-2.0
00004  *
00005  * Licensed under the Apache License, Version 2.0 (the "License");
00006  * you may not use this file except in compliance with the License.
00007  * You may obtain a copy of the License at
00008  *
00009  *     http://www.apache.org/licenses/LICENSE-2.0
00010  *
00011  * Unless required by applicable law or agreed to in writing, software
00012  * distributed under the License is distributed on an "AS IS" BASIS,
00013  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00014  * See the License for the specific language governing permissions and
00015  * limitations under the License.
00016  */
00017 #ifndef MBED_I2C_SLAVE_H
00018 #define MBED_I2C_SLAVE_H
00019 
00020 #include "platform/platform.h"
00021 
00022 #if DEVICE_I2CSLAVE || defined(DOXYGEN_ONLY)
00023 
00024 #include "hal/i2c_api.h"
00025 
00026 namespace mbed {
00027 /** \addtogroup drivers */
00028 
00029 /** An I2C Slave, used for communicating with an I2C Master device.
00030  *
00031  * @note Synchronization level: Not protected
00032  *
00033  * Example Simple I2C responder:
00034  * @code
00035  * #include <mbed.h>
00036  *
00037  * const int SLAVE_ADDRESS = 0xA0;
00038  * const char message[] = "Slave!";
00039  *
00040  * I2CSlave slave(I2C_SDA, I2C_SCL);
00041  *
00042  * int main() {
00043  *     slave.address(SLAVE_ADDRESS);
00044  *     while (1) {
00045  *         int operation = slave.receive();
00046  *         switch (operation) {
00047  *             case I2CSlave::ReadAddressed:
00048  *                 int status = slave.write(message, sizeof(message));
00049  *                 if (status == 0) {
00050  *                     printf("Written message: %s\n", message);
00051  *                 } else {
00052  *                     printf("Failed to write message.\n");
00053  *                 }
00054  *                 break;
00055  *             case I2CSlave::WriteGeneral:
00056  *                 int byte_read = slave.read();
00057  *                 printf("Read General: %c (%d)\n", byte_read, byte_read);
00058  *                 break;
00059  *             case I2CSlave::WriteAddressed:
00060  *                 int byte_read = slave.read();
00061  *                 printf("Read Addressed: %c (%d)\n", byte_read, byte_read);
00062  *                 break;
00063  *         }
00064  *     }
00065  * }
00066  * @endcode
00067  * @ingroup drivers
00068  */
00069 class I2CSlave {
00070 
00071 public:
00072     enum RxStatus {
00073         NoData         = 0,
00074         ReadAddressed  = 1,
00075         WriteGeneral   = 2,
00076         WriteAddressed = 3
00077     };
00078 
00079     /** Create an I2C Slave interface, connected to the specified pins.
00080      *
00081      *  @param sda I2C data line pin.
00082      *  @param scl I2C clock line pin.
00083      */
00084     I2CSlave(PinName sda, PinName scl);
00085 
00086     /** Set the frequency of the I2C interface.
00087      *
00088      *  @param hz The bus frequency in Hertz.
00089      */
00090     void frequency(int hz);
00091 
00092     /** Check if this I2C Slave has been addressed.
00093      *
00094      *  @return A status indicating if the device has been addressed and how.
00095      *  @retval NoData          The slave has not been addressed.
00096      *  @retval ReadAddressed   The master has requested a read from this slave.
00097      *  @retval WriteAddressed  The master is writing to this slave.
00098      *  @retval WriteGeneral    The master is writing to all slave.
00099      */
00100     int receive(void);
00101 
00102     /** Read specified number of bytes from an I2C master.
00103      *
00104      *  @param data   Pointer to the buffer to read data into.
00105      *  @param length Number of bytes to read.
00106      *
00107      *  @return Result of the operation.
00108      *  @retval 0       If the number of bytes read is equal to length requested.
00109      *  @retval nonzero On error or if the number of bytes read is less than requested.
00110      */
00111     int read(char *data, int length);
00112 
00113     /** Read a single byte from an I2C master.
00114      *
00115      *  @return The byte read.
00116      */
00117     int read(void);
00118 
00119     /** Write to an I2C master.
00120      *
00121      *  @param data   Pointer to the buffer containing the data to be sent.
00122      *  @param length Number of bytes to send.
00123      *
00124      *  @return
00125      *  @retval 0       If written all bytes successfully.
00126      *  @retval nonzero On error or if the number of bytes written is less than requested.
00127      */
00128     int write(const char *data, int length);
00129 
00130     /** Write a single byte to an I2C master.
00131      *
00132      *  @param data Value to write.
00133      *
00134      *  @return Result of the operation.
00135      *  @retval 0 If a NACK is received.
00136      *  @retval 1 If an ACK is received.
00137      *  @retval 2 On timeout.
00138      */
00139     int write(int data);
00140 
00141     /** Set the I2C slave address.
00142      *
00143      *  @param address The address to set for the slave (least significant bit is ignored).
00144      *
00145      *  @note If address is set to 0, the slave will only respond to the
00146      *  general call address.
00147      */
00148     void address(int address);
00149 
00150     /** Reset the I2C slave back into the known ready receiving state.
00151      */
00152     void stop(void);
00153 
00154 #if !defined(DOXYGEN_ONLY)
00155 
00156 protected:
00157     /* Internal i2c object identifying the resources */
00158     i2c_t _i2c;
00159 
00160 #endif //!defined(DOXYGEN_ONLY)
00161 };
00162 
00163 } // namespace mbed
00164 
00165 #endif
00166 
00167 #endif