I2C.cpp

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 #include "drivers/I2C.h"
00017 
00018 #if DEVICE_I2C
00019 
00020 #if DEVICE_I2C_ASYNCH
00021 #include "platform/mbed_sleep.h"
00022 #endif
00023 
00024 namespace mbed {
00025 
00026 I2C *I2C::_owner = NULL;
00027 SingletonPtr<PlatformMutex>  I2C::_mutex;
00028 
00029 I2C::I2C(PinName sda, PinName scl) :
00030 #if DEVICE_I2C_ASYNCH
00031                                      _irq(this), _usage(DMA_USAGE_NEVER),
00032 #endif
00033                                       _i2c(), _hz(100000) {
00034     // No lock needed in the constructor
00035 
00036     // The init function also set the frequency to 100000
00037     i2c_init(&_i2c, sda, scl);
00038 
00039     // Used to avoid unnecessary frequency updates
00040     _owner = this;
00041 }
00042 
00043 void I2C::frequency(int hz) {
00044     lock();
00045     _hz = hz;
00046 
00047     // We want to update the frequency even if we are already the bus owners
00048     i2c_frequency(&_i2c, _hz);
00049 
00050     // Updating the frequency of the bus we become the owners of it
00051     _owner = this;
00052     unlock();
00053 }
00054 
00055 void I2C::aquire() {
00056     lock();
00057     if (_owner != this) {
00058         i2c_frequency(&_i2c, _hz);
00059         _owner = this;
00060     }
00061     unlock();
00062 }
00063 
00064 // write - Master Transmitter Mode
00065 int I2C::write(int address, const char* data, int length, bool repeated) {
00066     lock();
00067     aquire();
00068 
00069     int stop = (repeated) ? 0 : 1;
00070     int written = i2c_write(&_i2c, address, data, length, stop);
00071 
00072     unlock();
00073     return length != written;
00074 }
00075 
00076 int I2C::write(int data) {
00077     lock();
00078     int ret = i2c_byte_write(&_i2c, data);
00079     unlock();
00080     return ret;
00081 }
00082 
00083 // read - Master Reciever Mode
00084 int I2C::read(int address, char* data, int length, bool repeated) {
00085     lock();
00086     aquire();
00087 
00088     int stop = (repeated) ? 0 : 1;
00089     int read = i2c_read(&_i2c, address, data, length, stop);
00090 
00091     unlock();
00092     return length != read;
00093 }
00094 
00095 int I2C::read(int ack) {
00096     lock();
00097     int ret;
00098     if (ack) {
00099         ret = i2c_byte_read(&_i2c, 0);
00100     } else {
00101         ret = i2c_byte_read(&_i2c, 1);
00102     }
00103     unlock();
00104     return ret;
00105 }
00106 
00107 void I2C::start(void) {
00108     lock();
00109     i2c_start(&_i2c);
00110     unlock();
00111 }
00112 
00113 void I2C::stop(void) {
00114     lock();
00115     i2c_stop(&_i2c);
00116     unlock();
00117 }
00118 
00119 void I2C::lock() {
00120     _mutex->lock();
00121 }
00122 
00123 void I2C::unlock() {
00124     _mutex->unlock();
00125 }
00126 
00127 #if DEVICE_I2C_ASYNCH
00128 
00129 int I2C::transfer(int address, const char *tx_buffer, int tx_length, char *rx_buffer, int rx_length, const event_callback_t& callback, int event, bool repeated)
00130 {
00131     lock();
00132     if (i2c_active(&_i2c)) {
00133         unlock();
00134         return -1; // transaction ongoing
00135     }
00136     sleep_manager_lock_deep_sleep();
00137     aquire();
00138 
00139     _callback = callback;
00140     int stop = (repeated) ? 0 : 1;
00141     _irq.callback(&I2C::irq_handler_asynch);
00142     i2c_transfer_asynch(&_i2c, (void *)tx_buffer, tx_length, (void *)rx_buffer, rx_length, address, stop, _irq.entry(), event, _usage);
00143     unlock();
00144     return 0;
00145 }
00146 
00147 void I2C::abort_transfer(void)
00148 {
00149     lock();
00150     i2c_abort_asynch(&_i2c);
00151     sleep_manager_unlock_deep_sleep();
00152     unlock();
00153 }
00154 
00155 void I2C::irq_handler_asynch(void)
00156 {
00157     int event = i2c_irq_handler_asynch(&_i2c);
00158     if (_callback && event) {
00159         _callback.call(event);
00160     }
00161     if (event) {
00162         sleep_manager_unlock_deep_sleep();
00163     }
00164 
00165 }
00166 
00167 
00168 #endif
00169 
00170 } // namespace mbed
00171 
00172 #endif