I2C.cpp

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2015 ARM Limited
00003  * SPDX-License-Identifier: Apache-2.0
00004  *
00005  * Licensed under the Apache License, Version 2.0 (the "License");
00006  * you may not use this file except in compliance with the License.
00007  * You may obtain a copy of the License at
00008  *
00009  *     http://www.apache.org/licenses/LICENSE-2.0
00010  *
00011  * Unless required by applicable law or agreed to in writing, software
00012  * distributed under the License is distributed on an "AS IS" BASIS,
00013  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00014  * See the License for the specific language governing permissions and
00015  * limitations under the License.
00016  */
00017 
00018 #include "drivers/I2C.h"
00019 #include "drivers/DigitalInOut.h"
00020 #include "platform/mbed_wait_api.h"
00021 
00022 #if DEVICE_I2C
00023 
00024 #if DEVICE_I2C_ASYNCH
00025 #include "platform/mbed_power_mgmt.h"
00026 #endif
00027 
00028 namespace mbed {
00029 
00030 I2C *I2C::_owner = NULL;
00031 SingletonPtr<PlatformMutex>  I2C::_mutex;
00032 
00033 I2C::I2C(PinName sda, PinName scl) :
00034 #if DEVICE_I2C_ASYNCH
00035     _irq(this), _usage(DMA_USAGE_NEVER), _deep_sleep_locked(false),
00036 #endif
00037     _i2c(), _hz(100000)
00038 {
00039     lock();
00040     // The init function also set the frequency to 100000
00041     _sda = sda;
00042     _scl = scl;
00043     recover(sda, scl);
00044     i2c_init(&_i2c, _sda, _scl);
00045     // Used to avoid unnecessary frequency updates
00046     _owner = this;
00047     unlock();
00048 }
00049 
00050 void I2C::frequency(int hz)
00051 {
00052     lock();
00053     _hz = hz;
00054 
00055     // We want to update the frequency even if we are already the bus owners
00056     i2c_frequency(&_i2c, _hz);
00057 
00058     // Updating the frequency of the bus we become the owners of it
00059     _owner = this;
00060     unlock();
00061 }
00062 
00063 void I2C::aquire()
00064 {
00065     lock();
00066     if (_owner != this) {
00067         i2c_frequency(&_i2c, _hz);
00068         _owner = this;
00069     }
00070     unlock();
00071 }
00072 
00073 // write - Master Transmitter Mode
00074 int I2C::write(int address, const char *data, int length, bool repeated)
00075 {
00076     lock();
00077     aquire();
00078 
00079     int stop = (repeated) ? 0 : 1;
00080     int written = i2c_write(&_i2c, address, data, length, stop);
00081 
00082     unlock();
00083     return length != written;
00084 }
00085 
00086 int I2C::write(int data)
00087 {
00088     lock();
00089     int ret = i2c_byte_write(&_i2c, data);
00090     unlock();
00091     return ret;
00092 }
00093 
00094 // read - Master Receiver Mode
00095 int I2C::read(int address, char *data, int length, bool repeated)
00096 {
00097     lock();
00098     aquire();
00099 
00100     int stop = (repeated) ? 0 : 1;
00101     int read = i2c_read(&_i2c, address, data, length, stop);
00102 
00103     unlock();
00104     return length != read;
00105 }
00106 
00107 int I2C::read(int ack)
00108 {
00109     lock();
00110     int ret;
00111     if (ack) {
00112         ret = i2c_byte_read(&_i2c, 0);
00113     } else {
00114         ret = i2c_byte_read(&_i2c, 1);
00115     }
00116     unlock();
00117     return ret;
00118 }
00119 
00120 void I2C::start(void)
00121 {
00122     lock();
00123     i2c_start(&_i2c);
00124     unlock();
00125 }
00126 
00127 void I2C::stop(void)
00128 {
00129     lock();
00130     i2c_stop(&_i2c);
00131     unlock();
00132 }
00133 
00134 void I2C::lock()
00135 {
00136     _mutex->lock();
00137 }
00138 
00139 void I2C::unlock()
00140 {
00141     _mutex->unlock();
00142 }
00143 
00144 int I2C::recover(PinName sda, PinName scl)
00145 {
00146     DigitalInOut pin_sda(sda, PIN_INPUT, PullNone, 1);
00147     DigitalInOut pin_scl(scl, PIN_INPUT, PullNone, 1);
00148 
00149     // Return as SCL is low and no access to become master.
00150     if (pin_scl == 0) {
00151         return I2C_ERROR_BUS_BUSY;
00152     }
00153 
00154     // Return successfully as SDA and SCL is high
00155     if (pin_sda == 1) {
00156         return 0;
00157     }
00158 
00159     // Send clock pulses, for device to recover 9
00160     pin_scl.mode(PullNone);
00161     pin_scl.output();
00162     for (int count = 0; count < 10; count++) {
00163         pin_scl.mode(PullNone);
00164         pin_scl = 0;
00165         wait_us(5);
00166         pin_scl.mode(PullUp);
00167         pin_scl = 1;
00168         wait_us(5);
00169     }
00170 
00171     // Send Stop
00172     pin_sda.output();
00173     pin_sda = 0;
00174     wait_us(5);
00175     pin_scl = 1;
00176     wait_us(5);
00177     pin_sda = 1;
00178     wait_us(5);
00179 
00180     pin_sda.input();
00181     pin_scl.input();
00182     if ((pin_scl == 0) || (pin_sda == 0)) {
00183         // Return as SCL is low and no access to become master.
00184         return I2C_ERROR_BUS_BUSY;
00185     }
00186 
00187     return 0;
00188 }
00189 
00190 #if DEVICE_I2C_ASYNCH
00191 
00192 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)
00193 {
00194     lock();
00195     if (i2c_active(&_i2c)) {
00196         unlock();
00197         return -1; // transaction ongoing
00198     }
00199     lock_deep_sleep();
00200     aquire();
00201 
00202     _callback = callback;
00203     int stop = (repeated) ? 0 : 1;
00204     _irq.callback(&I2C::irq_handler_asynch);
00205     i2c_transfer_asynch(&_i2c, (void *)tx_buffer, tx_length, (void *)rx_buffer, rx_length, address, stop, _irq.entry(), event, _usage);
00206     unlock();
00207     return 0;
00208 }
00209 
00210 void I2C::abort_transfer(void)
00211 {
00212     lock();
00213     i2c_abort_asynch(&_i2c);
00214     unlock_deep_sleep();
00215     unlock();
00216 }
00217 
00218 void I2C::irq_handler_asynch(void)
00219 {
00220     int event = i2c_irq_handler_asynch(&_i2c);
00221     if (_callback && event) {
00222         _callback.call(event);
00223     }
00224 
00225     if (event) {
00226         unlock_deep_sleep();
00227     }
00228 }
00229 
00230 void I2C::lock_deep_sleep()
00231 {
00232     if (_deep_sleep_locked == false) {
00233         sleep_manager_lock_deep_sleep();
00234         _deep_sleep_locked = true;
00235     }
00236 }
00237 
00238 void I2C::unlock_deep_sleep()
00239 {
00240     if (_deep_sleep_locked == true) {
00241         sleep_manager_unlock_deep_sleep();
00242         _deep_sleep_locked = false;
00243     }
00244 }
00245 
00246 #endif
00247 
00248 } // namespace mbed
00249 
00250 #endif