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_power_mgmt.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), _deep_sleep_locked(false),
00032 #endif
00033     _i2c(), _hz(100000)
00034 {
00035     // No lock needed in the constructor
00036 
00037     // The init function also set the frequency to 100000
00038     i2c_init(&_i2c, sda, scl);
00039 
00040     // Used to avoid unnecessary frequency updates
00041     _owner = this;
00042 }
00043 
00044 void I2C::frequency(int hz)
00045 {
00046     lock();
00047     _hz = hz;
00048 
00049     // We want to update the frequency even if we are already the bus owners
00050     i2c_frequency(&_i2c, _hz);
00051 
00052     // Updating the frequency of the bus we become the owners of it
00053     _owner = this;
00054     unlock();
00055 }
00056 
00057 void I2C::aquire()
00058 {
00059     lock();
00060     if (_owner != this) {
00061         i2c_frequency(&_i2c, _hz);
00062         _owner = this;
00063     }
00064     unlock();
00065 }
00066 
00067 // write - Master Transmitter Mode
00068 int I2C::write(int address, const char *data, int length, bool repeated)
00069 {
00070     lock();
00071     aquire();
00072 
00073     int stop = (repeated) ? 0 : 1;
00074     int written = i2c_write(&_i2c, address, data, length, stop);
00075 
00076     unlock();
00077     return length != written;
00078 }
00079 
00080 int I2C::write(int data)
00081 {
00082     lock();
00083     int ret = i2c_byte_write(&_i2c, data);
00084     unlock();
00085     return ret;
00086 }
00087 
00088 // read - Master Receiver Mode
00089 int I2C::read(int address, char *data, int length, bool repeated)
00090 {
00091     lock();
00092     aquire();
00093 
00094     int stop = (repeated) ? 0 : 1;
00095     int read = i2c_read(&_i2c, address, data, length, stop);
00096 
00097     unlock();
00098     return length != read;
00099 }
00100 
00101 int I2C::read(int ack)
00102 {
00103     lock();
00104     int ret;
00105     if (ack) {
00106         ret = i2c_byte_read(&_i2c, 0);
00107     } else {
00108         ret = i2c_byte_read(&_i2c, 1);
00109     }
00110     unlock();
00111     return ret;
00112 }
00113 
00114 void I2C::start(void)
00115 {
00116     lock();
00117     i2c_start(&_i2c);
00118     unlock();
00119 }
00120 
00121 void I2C::stop(void)
00122 {
00123     lock();
00124     i2c_stop(&_i2c);
00125     unlock();
00126 }
00127 
00128 void I2C::lock()
00129 {
00130     _mutex->lock();
00131 }
00132 
00133 void I2C::unlock()
00134 {
00135     _mutex->unlock();
00136 }
00137 
00138 #if DEVICE_I2C_ASYNCH
00139 
00140 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)
00141 {
00142     lock();
00143     if (i2c_active(&_i2c)) {
00144         unlock();
00145         return -1; // transaction ongoing
00146     }
00147     lock_deep_sleep();
00148     aquire();
00149 
00150     _callback = callback;
00151     int stop = (repeated) ? 0 : 1;
00152     _irq.callback(&I2C::irq_handler_asynch);
00153     i2c_transfer_asynch(&_i2c, (void *)tx_buffer, tx_length, (void *)rx_buffer, rx_length, address, stop, _irq.entry(), event, _usage);
00154     unlock();
00155     return 0;
00156 }
00157 
00158 void I2C::abort_transfer(void)
00159 {
00160     lock();
00161     i2c_abort_asynch(&_i2c);
00162     unlock_deep_sleep();
00163     unlock();
00164 }
00165 
00166 void I2C::irq_handler_asynch(void)
00167 {
00168     int event = i2c_irq_handler_asynch(&_i2c);
00169     if (_callback && event) {
00170         _callback.call(event);
00171     }
00172     if (event) {
00173         unlock_deep_sleep();
00174     }
00175 
00176 }
00177 
00178 void I2C::lock_deep_sleep()
00179 {
00180     if (_deep_sleep_locked == false) {
00181         sleep_manager_lock_deep_sleep();
00182         _deep_sleep_locked = true;
00183     }
00184 }
00185 
00186 void I2C::unlock_deep_sleep()
00187 {
00188     if (_deep_sleep_locked == true) {
00189         sleep_manager_unlock_deep_sleep();
00190         _deep_sleep_locked = false;
00191     }
00192 }
00193 
00194 #endif
00195 
00196 } // namespace mbed
00197 
00198 #endif