Mbed OS Reference | I2C.h Source File

 /* mbed Microcontroller Library
  * Copyright (c) 2006-2019 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 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/Callback.h"
 #endif
 
 namespace mbed {
 /** \defgroup drivers-public-api-i2c I2C
  * \ingroup drivers-public-api
  */
 
 /**
  * \defgroup drivers_I2C I2C class
  * \ingroup drivers-public-api-i2c
  * @{
  */
 
 /** 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
  */
 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);
 
     virtual ~I2C();
 
     /** Set the frequency of the I2C interface
      *
      *  @param hz The bus frequency in hertz
      */
     void frequency(int hz);
 
     /** Configure the timeout duration in microseconds for blocking transmission
     *
     *  @param timeout    Transmission timeout in microseconds.
     *
     *  @note If no timeout is set the default timeout is used.
     *        Default timeout value is based on I2C frequency.
     *        Byte timeout is computed as triple amount of time it would take
     *        to send 10bit over I2C and is expressed by the formula:
     *        byte_timeout = 3 * (1/frequency * 10 * 1000000)
     */
     void timeout(uint32_t timeout);
 
     /** 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);
 
 #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();
 
     static void irq_handler_asynch(i2c_t *obj, i2c_async_event_t *event, void *ctx);
     event_callback_t _callback;
     bool _deep_sleep_locked;
     bool _async_transfer_ongoing;
 #endif
 #endif
 
 #if !defined(DOXYGEN_ONLY)
 protected:
     void aquire();
 
     i2c_t _i2c;
     static I2C  *_owner;
     uint32_t _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
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