I2C.cpp

00001 /* mbed Microcontroller Library
00002  * Copyright (c) 2006-2019 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 I2C::I2C(const i2c_pinmap_t &static_pinmap) :
00051 #if DEVICE_I2C_ASYNCH
00052     _irq(this), _usage(DMA_USAGE_NEVER), _deep_sleep_locked(false),
00053 #endif
00054     _i2c(), _hz(100000)
00055 {
00056     lock();
00057     // The init function also set the frequency to 100000
00058     _sda = static_pinmap.sda_pin;
00059     _scl = static_pinmap.scl_pin;
00060     recover(static_pinmap.sda_pin, static_pinmap.scl_pin);
00061     i2c_init_direct(&_i2c, &static_pinmap);
00062     // Used to avoid unnecessary frequency updates
00063     _owner = this;
00064     unlock();
00065 }
00066 
00067 void I2C::frequency(int hz)
00068 {
00069     lock();
00070     _hz = hz;
00071 
00072     // We want to update the frequency even if we are already the bus owners
00073     i2c_frequency(&_i2c, _hz);
00074 
00075     // Updating the frequency of the bus we become the owners of it
00076     _owner = this;
00077     unlock();
00078 }
00079 
00080 void I2C::aquire()
00081 {
00082     lock();
00083     if (_owner != this) {
00084         i2c_frequency(&_i2c, _hz);
00085         _owner = this;
00086     }
00087     unlock();
00088 }
00089 
00090 // write - Master Transmitter Mode
00091 int I2C::write(int address, const char *data, int length, bool repeated)
00092 {
00093     lock();
00094     aquire();
00095 
00096     int stop = (repeated) ? 0 : 1;
00097     int written = i2c_write(&_i2c, address, data, length, stop);
00098 
00099     unlock();
00100     return length != written;
00101 }
00102 
00103 int I2C::write(int data)
00104 {
00105     lock();
00106     int ret = i2c_byte_write(&_i2c, data);
00107     unlock();
00108     return ret;
00109 }
00110 
00111 // read - Master Receiver Mode
00112 int I2C::read(int address, char *data, int length, bool repeated)
00113 {
00114     lock();
00115     aquire();
00116 
00117     int stop = (repeated) ? 0 : 1;
00118     int read = i2c_read(&_i2c, address, data, length, stop);
00119 
00120     unlock();
00121     return length != read;
00122 }
00123 
00124 int I2C::read(int ack)
00125 {
00126     lock();
00127     int ret;
00128     if (ack) {
00129         ret = i2c_byte_read(&_i2c, 0);
00130     } else {
00131         ret = i2c_byte_read(&_i2c, 1);
00132     }
00133     unlock();
00134     return ret;
00135 }
00136 
00137 void I2C::start(void)
00138 {
00139     lock();
00140     i2c_start(&_i2c);
00141     unlock();
00142 }
00143 
00144 void I2C::stop(void)
00145 {
00146     lock();
00147     i2c_stop(&_i2c);
00148     unlock();
00149 }
00150 
00151 void I2C::lock()
00152 {
00153     _mutex->lock();
00154 }
00155 
00156 void I2C::unlock()
00157 {
00158     _mutex->unlock();
00159 }
00160 
00161 int I2C::recover(PinName sda, PinName scl)
00162 {
00163     DigitalInOut pin_sda(sda, PIN_INPUT, PullNone, 1);
00164     DigitalInOut pin_scl(scl, PIN_INPUT, PullNone, 1);
00165 
00166     // Return as SCL is low and no access to become master.
00167     if (pin_scl == 0) {
00168         return I2C_ERROR_BUS_BUSY;
00169     }
00170 
00171     // Return successfully as SDA and SCL is high
00172     if (pin_sda == 1) {
00173         return 0;
00174     }
00175 
00176     // Send clock pulses, for device to recover 9
00177     pin_scl.mode(PullNone);
00178     pin_scl.output();
00179     for (int count = 0; count < 10; count++) {
00180         pin_scl.mode(PullNone);
00181         pin_scl = 0;
00182         wait_us(5);
00183         pin_scl.mode(PullUp);
00184         pin_scl = 1;
00185         wait_us(5);
00186     }
00187 
00188     // Send Stop
00189     pin_sda.output();
00190     pin_sda = 0;
00191     wait_us(5);
00192     pin_scl = 1;
00193     wait_us(5);
00194     pin_sda = 1;
00195     wait_us(5);
00196 
00197     pin_sda.input();
00198     pin_scl.input();
00199     if ((pin_scl == 0) || (pin_sda == 0)) {
00200         // Return as SCL is low and no access to become master.
00201         return I2C_ERROR_BUS_BUSY;
00202     }
00203 
00204     return 0;
00205 }
00206 
00207 #if DEVICE_I2C_ASYNCH
00208 
00209 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)
00210 {
00211     lock();
00212     if (i2c_active(&_i2c)) {
00213         unlock();
00214         return -1; // transaction ongoing
00215     }
00216     lock_deep_sleep();
00217     aquire();
00218 
00219     _callback = callback;
00220     int stop = (repeated) ? 0 : 1;
00221     _irq.callback(&I2C::irq_handler_asynch);
00222     i2c_transfer_asynch(&_i2c, (void *)tx_buffer, tx_length, (void *)rx_buffer, rx_length, address, stop, _irq.entry(), event, _usage);
00223     unlock();
00224     return 0;
00225 }
00226 
00227 void I2C::abort_transfer(void)
00228 {
00229     lock();
00230     i2c_abort_asynch(&_i2c);
00231     unlock_deep_sleep();
00232     unlock();
00233 }
00234 
00235 void I2C::irq_handler_asynch(void)
00236 {
00237     int event = i2c_irq_handler_asynch(&_i2c);
00238     if (_callback && event) {
00239         _callback.call(event);
00240     }
00241 
00242     if (event) {
00243         unlock_deep_sleep();
00244     }
00245 }
00246 
00247 void I2C::lock_deep_sleep()
00248 {
00249     if (_deep_sleep_locked == false) {
00250         sleep_manager_lock_deep_sleep();
00251         _deep_sleep_locked = true;
00252     }
00253 }
00254 
00255 void I2C::unlock_deep_sleep()
00256 {
00257     if (_deep_sleep_locked == true) {
00258         sleep_manager_unlock_deep_sleep();
00259         _deep_sleep_locked = false;
00260     }
00261 }
00262 
00263 #endif
00264 
00265 } // namespace mbed
00266 
00267 #endif