File content as of revision 58:3b55b7a41411:

/* 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.
 */
#include "i2c_api.h"

#if DEVICE_I2C

#include "cmsis.h"
#include "pinmap.h"
#include "error.h"

/* Timeout values for flags and events waiting loops. These timeouts are
   not based on accurate values, they just guarantee that the application will 
   not remain stuck if the I2C communication is corrupted. */   
#define FLAG_TIMEOUT ((int)0x1000)
#define LONG_TIMEOUT ((int)0x8000)

static const PinMap PinMap_I2C_SDA[] = {
    {PB_9,  I2C_1, STM_PIN_DATA(GPIO_Mode_AF_OD, 8)}, // GPIO_Remap_I2C1
    {NC,    NC,    0}
};

static const PinMap PinMap_I2C_SCL[] = {
    {PB_8,  I2C_1, STM_PIN_DATA(GPIO_Mode_AF_OD, 8)}, // GPIO_Remap_I2C1
    {NC,    NC,    0}
};

void i2c_init(i2c_t *obj, PinName sda, PinName scl) {  
    // Determine the I2C to use
    I2CName i2c_sda = (I2CName)pinmap_peripheral(sda, PinMap_I2C_SDA);
    I2CName i2c_scl = (I2CName)pinmap_peripheral(scl, PinMap_I2C_SCL);

    obj->i2c = (I2CName)pinmap_merge(i2c_sda, i2c_scl);
    
    if (obj->i2c == (I2CName)NC) {
        error("I2C pin mapping failed");
    }

    // Enable I2C clock
    if (obj->i2c == I2C_1) {    
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);
    }
    if (obj->i2c == I2C_2) {
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C2, ENABLE);
    }

    // Configure I2C pins
    pinmap_pinout(sda, PinMap_I2C_SDA);
    pinmap_pinout(scl, PinMap_I2C_SCL);
    pin_mode(sda, OpenDrain);
    pin_mode(scl, OpenDrain);
    
    // Reset to clear pending flags if any
    i2c_reset(obj);
    
    // I2C configuration
    i2c_frequency(obj, 100000); // 100 kHz per default    
}

void i2c_frequency(i2c_t *obj, int hz) {
    I2C_TypeDef *i2c = (I2C_TypeDef *)(obj->i2c);
    I2C_InitTypeDef I2C_InitStructure;
  
    if ((hz != 0) && (hz <= 400000)) {
        // I2C configuration
        I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
        I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;
        I2C_InitStructure.I2C_OwnAddress1 = 0;
        I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
        I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
        I2C_InitStructure.I2C_ClockSpeed = hz;
        I2C_Cmd(i2c, ENABLE);
        I2C_Init(i2c, &I2C_InitStructure);  
    }
}

inline int i2c_start(i2c_t *obj) {
    I2C_TypeDef *i2c = (I2C_TypeDef *)(obj->i2c);
    int timeout;
  
    I2C_ClearFlag(i2c, I2C_FLAG_AF); // Clear Acknowledge failure flag
  
    // Generate the START condition
    I2C_GenerateSTART(i2c, ENABLE);  
  
    // Wait the START condition has been correctly sent
    timeout = FLAG_TIMEOUT;
    //while (I2C_CheckEvent(i2c, I2C_EVENT_MASTER_MODE_SELECT) == ERROR) {
    while (I2C_GetFlagStatus(i2c, I2C_FLAG_SB) == RESET) {
      if ((timeout--) == 0) {
          return 1;
      }
    }
    
    return 0;
}

inline int i2c_stop(i2c_t *obj) {
    I2C_TypeDef *i2c = (I2C_TypeDef *)(obj->i2c);
  
    I2C_GenerateSTOP(i2c, ENABLE);
  
    return 0;
}

int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
    I2C_TypeDef *i2c = (I2C_TypeDef *)(obj->i2c);
    int timeout;
    int count;
    int value;
  
    if (length == 0) return 0;

/*
    // Wait until the bus is not busy anymore
    timeout = LONG_TIMEOUT;
    while (I2C_GetFlagStatus(i2c, I2C_FLAG_BUSY) == SET) {
        if ((timeout--) == 0) {
            return 0;
        }
    }
*/
  
    i2c_start(obj);

    // Send slave address for read
    I2C_Send7bitAddress(i2c, address, I2C_Direction_Receiver);  

    // Wait address is acknowledged
    timeout = FLAG_TIMEOUT;
    while (I2C_CheckEvent(i2c, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED) == ERROR) {
      if ((timeout--) == 0) {
          return 0;
      }
    }
    
    // Read all bytes except last one
    for (count = 0; count < (length - 1); count++) {
        value = i2c_byte_read(obj, 0);
        data[count] = (char)value;
    }
    
    // If not repeated start, send stop.
    // Warning: must be done BEFORE the data is read.
    if (stop) {
        i2c_stop(obj);
    }

    // Read the last byte
    value = i2c_byte_read(obj, 1);
    data[count] = (char)value;
    
    return length;
}

int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
    I2C_TypeDef *i2c = (I2C_TypeDef *)(obj->i2c);
    int timeout;
    int count;
  
/*
    // Wait until the bus is not busy anymore
    timeout = LONG_TIMEOUT;
    while (I2C_GetFlagStatus(i2c, I2C_FLAG_BUSY) == SET) {
        if ((timeout--) == 0) {
            return 0;
        }
    }
*/

    i2c_start(obj);

    // Send slave address for write
    I2C_Send7bitAddress(i2c, address, I2C_Direction_Transmitter);
  
    // Wait address is acknowledged
    timeout = FLAG_TIMEOUT;
    while (I2C_CheckEvent(i2c, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED) == ERROR) {
      if ((timeout--) == 0) {
          return 0;
      }
    }

    for (count = 0; count < length; count++) {
        if (i2c_byte_write(obj, data[count]) != 1) {
            i2c_stop(obj);
            return 0;
        }
    }

    // If not repeated start, send stop.
    if (stop) {
        i2c_stop(obj);
    }

    return count;
}

int i2c_byte_read(i2c_t *obj, int last) {
    I2C_TypeDef *i2c = (I2C_TypeDef *)(obj->i2c);
    uint8_t data;
    int timeout;
  
    if (last) {
        // Don't acknowledge the last byte
        I2C_AcknowledgeConfig(i2c, DISABLE);
    } else {
        // Acknowledge the byte
        I2C_AcknowledgeConfig(i2c, ENABLE);
    }

    // Wait until the byte is received
    timeout = FLAG_TIMEOUT;
    while (I2C_GetFlagStatus(i2c, I2C_FLAG_RXNE) == RESET) {
      if ((timeout--) == 0) {
          return 0;
      }
    }

    data = I2C_ReceiveData(i2c);
    
    return (int)data;
}

int i2c_byte_write(i2c_t *obj, int data) {
    I2C_TypeDef *i2c = (I2C_TypeDef *)(obj->i2c);
    int timeout;

    I2C_SendData(i2c, (uint8_t)data);

    // Wait until the byte is transmitted
    timeout = FLAG_TIMEOUT;  
    //while (I2C_CheckEvent(i2c, I2C_EVENT_MASTER_BYTE_TRANSMITTED) == ERROR) {
    while ((I2C_GetFlagStatus(i2c, I2C_FLAG_TXE) == RESET) &&
           (I2C_GetFlagStatus(i2c, I2C_FLAG_BTF) == RESET)) {
        if ((timeout--) == 0) {
            return 0;
        }
    }
    
    return 1;
}

void i2c_reset(i2c_t *obj) {
    if (obj->i2c == I2C_1) {    
        RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C1, ENABLE);
        RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C1, DISABLE);
    }
    if (obj->i2c == I2C_2) {
        RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C2, ENABLE);
        RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C2, DISABLE);      
    }
}

#if DEVICE_I2CSLAVE

void i2c_slave_address(i2c_t *obj, int idx, uint32_t address, uint32_t mask) {
    I2C_TypeDef *i2c = (I2C_TypeDef *)(obj->i2c);
    uint16_t tmpreg;
  
    // Get the old register value
    tmpreg = i2c->OAR1;
    // Reset address bits
    tmpreg &= 0xFC00;
    // Set new address
    tmpreg |= (uint16_t)((uint16_t)address & (uint16_t)0x00FE); // 7-bits
    // Store the new register value
    i2c->OAR1 = tmpreg;
}

void i2c_slave_mode(i2c_t *obj, int enable_slave) {
    // Nothing to do
}

// See I2CSlave.h
#define NoData         0 // the slave has not been addressed
#define ReadAddressed  1 // the master has requested a read from this slave (slave = transmitter)
#define WriteGeneral   2 // the master is writing to all slave
#define WriteAddressed 3 // the master is writing to this slave (slave = receiver)

int i2c_slave_receive(i2c_t *obj) {
    // TO BE DONE
    return(0);
}

int i2c_slave_read(i2c_t *obj, char *data, int length) {
    int count = 0;
 
    // Read all bytes
    for (count = 0; count < length; count++) {
        data[count] = i2c_byte_read(obj, 0);
    }
    
    return count;
}

int i2c_slave_write(i2c_t *obj, const char *data, int length) {
    int count = 0;
 
    // Write all bytes
    for (count = 0; count < length; count++) {
        i2c_byte_write(obj, data[count]);
    }
    
    return count;
}


#endif // DEVICE_I2CSLAVE

#endif // DEVICE_I2C