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I2C.h
00001 /* mbed Microcontroller Library 00002 * Copyright (c) 2006-2015 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_H 00017 #define MBED_I2C_H 00018 00019 #include "platform/platform.h" 00020 00021 #if DEVICE_I2C 00022 00023 #include "hal/i2c_api.h" 00024 #include "platform/SingletonPtr.h" 00025 #include "platform/PlatformMutex.h" 00026 00027 #if DEVICE_I2C_ASYNCH 00028 #include "platform/CThunk.h" 00029 #include "hal/dma_api.h" 00030 #include "platform/FunctionPointer.h" 00031 #endif 00032 00033 namespace mbed { 00034 /** \addtogroup drivers */ 00035 /** @{*/ 00036 00037 /** An I2C Master, used for communicating with I2C slave devices 00038 * 00039 * @Note Synchronization level: Thread safe 00040 * 00041 * Example: 00042 * @code 00043 * // Read from I2C slave at address 0x62 00044 * 00045 * #include "mbed.h" 00046 * 00047 * I2C i2c(p28, p27); 00048 * 00049 * int main() { 00050 * int address = 0x62; 00051 * char data[2]; 00052 * i2c.read(address, data, 2); 00053 * } 00054 * @endcode 00055 */ 00056 class I2C { 00057 00058 public: 00059 enum RxStatus { 00060 NoData, 00061 MasterGeneralCall, 00062 MasterWrite, 00063 MasterRead 00064 }; 00065 00066 enum Acknowledge { 00067 NoACK = 0, 00068 ACK = 1 00069 }; 00070 00071 /** Create an I2C Master interface, connected to the specified pins 00072 * 00073 * @param sda I2C data line pin 00074 * @param scl I2C clock line pin 00075 */ 00076 I2C(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 /** Read from an I2C slave 00085 * 00086 * Performs a complete read transaction. The bottom bit of 00087 * the address is forced to 1 to indicate a read. 00088 * 00089 * @param address 8-bit I2C slave address [ addr | 1 ] 00090 * @param data Pointer to the byte-array to read data in to 00091 * @param length Number of bytes to read 00092 * @param repeated Repeated start, true - don't send stop at end 00093 * 00094 * @returns 00095 * 0 on success (ack), 00096 * non-0 on failure (nack) 00097 */ 00098 int read(int address, char *data, int length, bool repeated = false); 00099 00100 /** Read a single byte from the I2C bus 00101 * 00102 * @param ack indicates if the byte is to be acknowledged (1 = acknowledge) 00103 * 00104 * @returns 00105 * the byte read 00106 */ 00107 int read(int ack); 00108 00109 /** Write to an I2C slave 00110 * 00111 * Performs a complete write transaction. The bottom bit of 00112 * the address is forced to 0 to indicate a write. 00113 * 00114 * @param address 8-bit I2C slave address [ addr | 0 ] 00115 * @param data Pointer to the byte-array data to send 00116 * @param length Number of bytes to send 00117 * @param repeated Repeated start, true - do not send stop at end 00118 * 00119 * @returns 00120 * 0 on success (ack), 00121 * non-0 on failure (nack) 00122 */ 00123 int write(int address, const char *data, int length, bool repeated = false); 00124 00125 /** Write single byte out on the I2C bus 00126 * 00127 * @param data data to write out on bus 00128 * 00129 * @returns 00130 * '0' - NAK was received 00131 * '1' - ACK was received, 00132 * '2' - timeout 00133 */ 00134 int write(int data); 00135 00136 /** Creates a start condition on the I2C bus 00137 */ 00138 00139 void start(void); 00140 00141 /** Creates a stop condition on the I2C bus 00142 */ 00143 void stop(void); 00144 00145 /** Acquire exclusive access to this I2C bus 00146 */ 00147 virtual void lock(void); 00148 00149 /** Release exclusive access to this I2C bus 00150 */ 00151 virtual void unlock(void); 00152 00153 virtual ~I2C() { 00154 // Do nothing 00155 } 00156 00157 #if DEVICE_I2C_ASYNCH 00158 00159 /** Start non-blocking I2C transfer. 00160 * 00161 * @param address 8/10 bit I2c slave address 00162 * @param tx_buffer The TX buffer with data to be transfered 00163 * @param tx_length The length of TX buffer in bytes 00164 * @param rx_buffer The RX buffer which is used for received data 00165 * @param rx_length The length of RX buffer in bytes 00166 * @param event The logical OR of events to modify 00167 * @param callback The event callback function 00168 * @param repeated Repeated start, true - do not send stop at end 00169 * @return Zero if the transfer has started, or -1 if I2C peripheral is busy 00170 */ 00171 int transfer(int address, const char *tx_buffer, int tx_length, char *rx_buffer, int rx_length, const event_callback_t& callback, int event = I2C_EVENT_TRANSFER_COMPLETE, bool repeated = false); 00172 00173 /** Abort the on-going I2C transfer 00174 */ 00175 void abort_transfer(); 00176 protected: 00177 void irq_handler_asynch(void); 00178 event_callback_t _callback; 00179 CThunk<I2C> _irq; 00180 DMAUsage _usage; 00181 #endif 00182 00183 protected: 00184 void aquire(); 00185 00186 i2c_t _i2c; 00187 static I2C *_owner; 00188 int _hz; 00189 static SingletonPtr<PlatformMutex> _mutex; 00190 }; 00191 00192 } // namespace mbed 00193 00194 #endif 00195 00196 #endif 00197 00198 /** @}*/
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