text: /* mbed Microcontroller Library
   * Copyright (c) 2006-2015 ARM Limited
   * SPDX-License-Identifier: Apache-2.0
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  #ifndef MBED_I2C_H
  #define MBED_I2C_H
  
  #include "platform/platform.h"
  #include "hal/gpio_api.h"
  
  #if defined (DEVICE_I2C) || defined(DOXYGEN_ONLY)
  
  #include "hal/i2c_api.h"
  #include "platform/SingletonPtr.h"
  #include "platform/PlatformMutex.h"
  #include "platform/NonCopyable.h"
  
  #if DEVICE_I2C_ASYNCH
  #include "platform/CThunk.h"
  #include "hal/dma_api.h"
  #include "platform/FunctionPointer.h"
  #endif
  
  namespace mbed {
  /** \addtogroup drivers */
  
  /** An I2C Master, used for communicating with I2C slave devices
   *
   * @note Synchronization level: Thread safe
   *
   * Example:
   * @code
   * Read temperature from LM75BD
   * #include "mbed.h"
   * I2C i2c(I2C_SDA , I2C_SCL);
   * const int addr7bit = 0x48;      // 7-bit I2C address
   * const int addr8bit = 0x48 << 1; // 8-bit I2C address, 0x90
   *
   * int main() {
   *     char cmd[2];
   *     while (1) {
   *         cmd[0] = 0x01;
   *         cmd[1] = 0x00;
   *
   *         // read and write takes the 8-bit version of the address.
   *         // set up configuration register (at 0x01)
   *         i2c.write(addr8bit, cmd, 2);
   *
   *         wait(0.5);
   *
   *         // read temperature register
   *         cmd[0] = 0x00;
   *         i2c.write(addr8bit, cmd, 1);
   *         i2c.read( addr8bit, cmd, 2);
   *
   *         float tmp = (float((cmd[0]<<8)|cmd[1]) / 256.0);
   *         printf("Temp = %.2f\n", tmp);
   *   }
   * }
   * @endcode
   * @ingroup drivers
   */
  class I2C : private NonCopyable<I2C> {
  
  public:
      enum RxStatus {
          NoData,
          MasterGeneralCall,
          MasterWrite,
          MasterRead
      };
  
      enum Acknowledge {
          NoACK = 0,
          ACK   = 1
      };
  
      /** Create an I2C Master interface, connected to the specified pins
       *
       *  @param sda I2C data line pin
       *  @param scl I2C clock line pin
       */
      I2C(PinName sda, PinName scl);
  
      /** Set the frequency of the I2C interface
       *
       *  @param hz The bus frequency in hertz
       */
      void frequency(int hz);
  
      /** Read from an I2C slave
       *
       * Performs a complete read transaction. The bottom bit of
       * the address is forced to 1 to indicate a read.
       *
       *  @param address 8-bit I2C slave address [ addr | 1 ]
       *  @param data Pointer to the byte-array to read data in to
       *  @param length Number of bytes to read
       *  @param repeated Repeated start, true - don't send stop at end
       *         default value is false.
       *
       *  @returns
       *       0 on success (ack),
       *       nonzero on failure (nack)
       */
      int read(int address, char *data, int length, bool repeated = false);
  
      /** Read a single byte from the I2C bus
       *
       *  @param ack indicates if the byte is to be acknowledged (1 = acknowledge)
       *
       *  @returns
       *    the byte read
       */
      int read(int ack);
  
      /** Write to an I2C slave
       *
       * Performs a complete write transaction. The bottom bit of
       * the address is forced to 0 to indicate a write.
       *
       *  @param address 8-bit I2C slave address [ addr | 0 ]
       *  @param data Pointer to the byte-array data to send
       *  @param length Number of bytes to send
       *  @param repeated Repeated start, true - do not send stop at end
       *         default value is false.
       *
       *  @returns
       *       0 on success (ack),
       *       nonzero on failure (nack)
       */
      int write(int address, const char *data, int length, bool repeated = false);
  
      /** Write single byte out on the I2C bus
       *
       *  @param data data to write out on bus
       *
       *  @returns
       *    '0' - NAK was received
       *    '1' - ACK was received,
       *    '2' - timeout
       */
      int write(int data);
  
      /** Creates a start condition on the I2C bus
       */
      void start(void);
  
      /** Creates a stop condition on the I2C bus
       */
      void stop(void);
  
      /** Acquire exclusive access to this I2C bus
       */
      virtual void lock(void);
  
      /** Release exclusive access to this I2C bus
       */
      virtual void unlock(void);
  
      virtual ~I2C()
      {
          // Do nothing
      }
  
  #if DEVICE_I2C_ASYNCH
  
      /** Start nonblocking I2C transfer.
       *
       * This function locks the deep sleep until any event has occurred
       *
       * @param address   8/10 bit I2C slave address
       * @param tx_buffer The TX buffer with data to be transferred
       * @param tx_length The length of TX buffer in bytes
       * @param rx_buffer The RX buffer, which is used for received data
       * @param rx_length The length of RX buffer in bytes
       * @param event     The logical OR of events to modify
       * @param callback  The event callback function
       * @param repeated Repeated start, true - do not send stop at end
       *        default value is false.
       *
       * @returns Zero if the transfer has started, or -1 if I2C peripheral is busy
       */
      int transfer(int address, const char *tx_buffer, int tx_length, char *rx_buffer, int rx_length, const event_callback_t &callback, int event = I2C_EVENT_TRANSFER_COMPLETE, bool repeated = false);
  
      /** Abort the ongoing I2C transfer
       */
      void abort_transfer();
  
  #if !defined(DOXYGEN_ONLY)
  protected:
      /** Lock deep sleep only if it is not yet locked */
      void lock_deep_sleep();
  
      /** Unlock deep sleep only if it has been locked */
      void unlock_deep_sleep();
  
      void irq_handler_asynch(void);
      event_callback_t _callback;
      CThunk<I2C> _irq;
      DMAUsage _usage;
      bool _deep_sleep_locked;
  #endif
  #endif
  
  #if !defined(DOXYGEN_ONLY)
  protected:
      void aquire();
  
      i2c_t _i2c;
      static I2C  *_owner;
      int    _hz;
      static SingletonPtr<PlatformMutex> _mutex;
      PinName _sda;
      PinName _scl;
  
  private:
      /** Recover I2C bus, when stuck with SDA low
       *  @note : Initialization of I2C bus is required after this API.
       *
       *  @param sda I2C data line pin
       *  @param scl I2C clock line pin
       *
       * @returns
       *    '0' - Successfully recovered
       *    'I2C_ERROR_BUS_BUSY' - In case of failure
       *
       */
      int recover(PinName sda, PinName scl);
  #endif
  };
  
  } // namespace mbed
  
  #endif
  
  #endif
  