I2C.cpp

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2013 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 "I2C.h"
00017 
00018 #if DEVICE_I2C
00019 
00020 namespace mbed {
00021 
00022 I2C *I2C::_owner = NULL;
00023 
00024 I2C::I2C(PinName sda, PinName scl) : _i2c(), _hz(100000) {
00025     // The init function also set the frequency to 100000
00026     i2c_init(&_i2c, sda, scl);
00027 
00028     // Used to avoid unnecessary frequency updates
00029     _owner = this;
00030 }
00031 
00032 void I2C::frequency(int hz) {
00033     _hz = hz;
00034 
00035     // We want to update the frequency even if we are already the bus owners
00036     i2c_frequency(&_i2c, _hz);
00037 
00038     // Updating the frequency of the bus we become the owners of it
00039     _owner = this;
00040 }
00041 
00042 void I2C::aquire() {
00043     if (_owner != this) {
00044         i2c_frequency(&_i2c, _hz);
00045         _owner = this;
00046     }
00047 }
00048 
00049 // write - Master Transmitter Mode
00050 int I2C::write(int address, const char* data, int length, bool repeated) {
00051     aquire();
00052 
00053     int stop = (repeated) ? 0 : 1;
00054     int written = i2c_write(&_i2c, address, data, length, stop);
00055 
00056     return length != written;
00057 }
00058 
00059 int I2C::write(int data) {
00060     return i2c_byte_write(&_i2c, data);
00061 }
00062 
00063 // read - Master Reciever Mode
00064 int I2C::read(int address, char* data, int length, bool repeated) {
00065     aquire();
00066 
00067     int stop = (repeated) ? 0 : 1;
00068     int read = i2c_read(&_i2c, address, data, length, stop);
00069 
00070     return length != read;
00071 }
00072 
00073 int I2C::read(int ack) {
00074     if (ack) {
00075         return i2c_byte_read(&_i2c, 0);
00076     } else {
00077         return i2c_byte_read(&_i2c, 1);
00078     }
00079 }
00080 
00081 void I2C::start(void) {
00082     i2c_start(&_i2c);
00083 }
00084 
00085 void I2C::stop(void) {
00086     i2c_stop(&_i2c);
00087 }
00088 
00089 } // namespace mbed
00090 
00091 #endif