I2CSlave

Use I2C Slave to communicate with I2C Master.

Synchronization level: not protected.

API

 
 /* mbed Microcontroller Library
  * Copyright (c) 2006-2013 ARM Limited
  *
  * 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_SLAVE_H
 #define MBED_I2C_SLAVE_H
 
 #include "platform/platform.h"
 
 #if defined (DEVICE_I2CSLAVE) || defined(DOXYGEN_ONLY)
 
 #include "hal/i2c_api.h"
 
 namespace mbed {
 /** \addtogroup drivers */
 
 /** An I2C Slave, used for communicating with an I2C Master device
  *
  * @note Synchronization level: Not protected
  *
  * Example:
  * @code
  * // Simple I2C responder
  * #include <mbed.h>
  *
  * I2CSlave slave(p9, p10);
  *
  * int main() {
  * char buf[10];
  * char msg[] = "Slave!";
  *
  * slave.address(0xA0);
  * while (1) {
  * int i = slave.receive();
  * switch (i) {
  * case I2CSlave::ReadAddressed:
  * slave.write(msg, strlen(msg) + 1); // Includes null char
  * break;
  * case I2CSlave::WriteGeneral:
  * slave.read(buf, 10);
  * printf("Read G: %s\n", buf);
  * break;
  * case I2CSlave::WriteAddressed:
  * slave.read(buf, 10);
  * printf("Read A: %s\n", buf);
  * break;
  * }
  * for(int i = 0; i < 10; i++) buf[i] = 0; // Clear buffer
  * }
  * }
  * @endcode
  * @ingroup drivers
  */
 class I2CSlave {
 
 public:
  enum RxStatus {
  NoData = 0,
  ReadAddressed = 1,
  WriteGeneral = 2,
  WriteAddressed = 3
  };
 
  /** Create an I2C Slave interface, connected to the specified pins.
  *
  * @param sda I2C data line pin
  * @param scl I2C clock line pin
  */
  I2CSlave(PinName sda, PinName scl);
 
  /** Set the frequency of the I2C interface
  *
  * @param hz The bus frequency in hertz
  */
  void frequency(int hz);
 
  /** Checks to see if this I2C Slave has been addressed.
  *
  * @returns
  * A status indicating if the device has been addressed, and how
  * - NoData - the slave has not been addressed
  * - ReadAddressed - the master has requested a read from this slave
  * - WriteAddressed - the master is writing to this slave
  * - WriteGeneral - the master is writing to all slave
  */
  int receive(void);
 
  /** Read from an I2C master.
  *
  * @param data pointer to the byte array to read data in to
  * @param length maximum number of bytes to read
  *
  * @returns
  * 0 on success,
  * non-0 otherwise
  */
  int read(char *data, int length);
 
  /** Read a single byte from an I2C master.
  *
  * @returns
  * the byte read
  */
  int read(void);
 
  /** Write to an I2C master.
  *
  * @param data pointer to the byte array to be transmitted
  * @param length the number of bytes to transmite
  *
  * @returns
  * 0 on success,
  * non-0 otherwise
  */
  int write(const char *data, int length);
 
  /** Write a single byte to an I2C master.
  *
  * @param data the byte to write
  *
  * @returns
  * '1' if an ACK was received,
  * '0' otherwise
  */
  int write(int data);
 
  /** Sets the I2C slave address.
  *
  * @param address The address to set for the slave (ignoring the least
  * signifcant bit). If set to 0, the slave will only respond to the
  * general call address.
  */
  void address(int address);
 
  /** Reset the I2C slave back into the known ready receiving state.
  */
  void stop(void);
 
 protected:
  i2c_t _i2c;
 };
 
 } // namespace mbed
 
 #endif
 
 #endif
void stop(void)
int receive(void)
void address(int address)
int read(void)
int write(const char *data, int length)
I2CSlave(PinName sda, PinName scl)
void frequency(int hz)
Definition: AnalogIn.h:27
Definition: I2CSlave.h:65

Example

Try this example to see how an I2C responder works.

#include <mbed.h>

I2CSlave slave(p9, p10);

int main() {
   char buf[10];
   char msg[] = "Slave!";

   slave.address(0xA0);
   while (1) {
       int i = slave.receive();
       switch (i) {
           case I2CSlave::ReadAddressed:
               slave.write(msg, strlen(msg) + 1); // Includes null char
               break;
           case I2CSlave::WriteGeneral:
               slave.read(buf, 10);
               printf("Read G: %s\n", buf);
               break;
           case I2CSlave::WriteAddressed:
               slave.read(buf, 10);
               printf("Read A: %s\n", buf);
               break;
       }
       for(int i = 0; i < 10; i++) buf[i] = 0;    // Clear buffer
   }
}