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