File content as of revision 85:e1a8e879a6a9:

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



static const PinMap PinMap_I2C_SDA[] = {
    {p22, I2C_0, 1},
    {p13, I2C_1, 2},
    {NC  , NC   , 0}
};

static const PinMap PinMap_I2C_SCL[] = {
    {p20, I2C_0, 1},
    {p15, I2C_1, 2},
    {NC  , NC,    0}
};

uint8_t addrSet=0;

void i2c_interface_enable(i2c_t *obj){
    obj->i2c->ENABLE = (TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos);
}

void twi_master_init(i2c_t *obj, PinName sda, PinName scl, int frequency) {
    NRF_GPIO->PIN_CNF[scl]  = ((GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos) |
                               (GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos) |
                               (GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos) |
                               (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos) |
                               (GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos));

    NRF_GPIO->PIN_CNF[sda]  = ((GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos) |
                               (GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos) |
                               (GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos) |
                               (GPIO_PIN_CNF_DRIVE_S0D1 << GPIO_PIN_CNF_DRIVE_Pos) |
                               (GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos));

    obj->i2c->PSELSCL               = scl;
    obj->i2c->PSELSDA               = sda;        
    // set default frequency at 100k
    i2c_frequency(obj, frequency);
    i2c_interface_enable(obj);
}
void i2c_init(i2c_t *obj, PinName sda, PinName scl) {
    // determine the SPI to use
    I2CName i2c_sda = (I2CName)pinmap_peripheral(sda, PinMap_I2C_SDA);
    I2CName i2c_scl = (I2CName)pinmap_peripheral(scl, PinMap_I2C_SCL);
    I2CName i2c     = (I2CName)pinmap_merge(i2c_sda,i2c_scl);
    obj->i2c        = (NRF_TWI_Type            *)i2c;
    
    if ((int)obj->i2c == NC) {
        error("I2C pin mapping failed");
    }

    obj->scl=scl;
    obj->sda=sda;
    obj->i2c->EVENTS_ERROR = 0;
    obj->i2c->ENABLE       = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos; 
    obj->i2c->POWER        = 0; 
    
    for(int i=0;i<100;i++){
    }
    
    obj->i2c->POWER        = 1; 
    twi_master_init(obj,sda,scl,100000);
}
void i2c_reset(i2c_t *obj) {
    obj->i2c->EVENTS_ERROR = 0;
    obj->i2c->ENABLE       = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos; 
    obj->i2c->POWER        = 0; 
    for(int i=0;i<100;i++){
    }
    
    obj->i2c->POWER        = 1; 
    twi_master_init(obj,obj->sda,obj->scl,obj->freq);
}

int i2c_start(i2c_t *obj) {
    int status = 0;
    i2c_reset(obj);
    addrSet=0;
    return status;
}

int i2c_stop(i2c_t *obj) {
    int timeOut = 100000;
    obj->i2c->EVENTS_STOPPED = 0;
    // write the stop bit
    obj->i2c->TASKS_STOP = 1;
    while(!obj->i2c->EVENTS_STOPPED){
        timeOut--;
        if(timeOut<0)
            return 1;
    }    
    addrSet = 0;
    i2c_reset(obj);
    return 0;
}


int i2c_do_write(i2c_t *obj, int value) {
    int timeOut = 100000;
    obj->i2c->TXD = value;
    while(!obj->i2c->EVENTS_TXDSENT){
        timeOut--;
        if(timeOut<0)
            return 1;
    }
    obj->i2c->EVENTS_TXDSENT = 0;    
    return 0;
}

int i2c_do_read(i2c_t *obj, char * data, int last) {
    int timeOut = 100000;
    while(!obj->i2c->EVENTS_RXDREADY){
        timeOut--;
        if(timeOut<0)
            return 1;
    }
    obj->i2c->EVENTS_RXDREADY       = 0;

    if (last){
        obj->i2c->TASKS_STOP = 1;
    }
    *data = obj->i2c->RXD;
    
    for(int i=0;i<320;i++){
    }
    
    obj->i2c->TASKS_RESUME = 1;
    
    return 0;
}


void i2c_frequency(i2c_t *obj, int hz) {
    if(hz<250000){
        obj->freq           = 100000;
        obj->i2c->FREQUENCY = (TWI_FREQUENCY_FREQUENCY_K100 << TWI_FREQUENCY_FREQUENCY_Pos);
    }
    else if(hz<400000){
        obj->freq           = 250000;
        obj->i2c->FREQUENCY = (TWI_FREQUENCY_FREQUENCY_K250 << TWI_FREQUENCY_FREQUENCY_Pos);
    }
    else{
        obj->freq           = 400000;
        obj->i2c->FREQUENCY = (TWI_FREQUENCY_FREQUENCY_K400 << TWI_FREQUENCY_FREQUENCY_Pos);
    }
}

int checkError(i2c_t *obj){
    if (obj->i2c->EVENTS_ERROR == 1){        
        if (obj->i2c->ERRORSRC & TWI_ERRORSRC_ANACK_Msk){            
            obj->i2c->EVENTS_ERROR  = 0;
            obj->i2c->TASKS_STOP    = 1;            
            return I2C_ERROR_BUS_BUSY;
        }
        
        obj->i2c->EVENTS_ERROR  = 0;
        obj->i2c->TASKS_STOP    = 1;
        return I2C_ERROR_NO_SLAVE; 
    }    
    return 0;
}

int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
    int status,count,errorResult;
    obj->i2c->ADDRESS         = (address>>1);
    obj->i2c->SHORTS          = 0;
    obj->i2c->EVENTS_RXDREADY = 0;
    obj->i2c->TASKS_STARTRX   = 1;
    
    // Read in all except last byte
    for (count = 0; count < (length - 1); count++) {
        status = i2c_do_read(obj,&data[count], 0);
        if (status) {            
            errorResult = checkError(obj);
            i2c_reset(obj);
            if(errorResult<0){
                return errorResult;
            }
            return count;
        }
    }

    // read in last byte
    status = i2c_do_read(obj,&data[length-1], 1);
    if (status) {
        i2c_reset(obj);
        return length - 1;
    }
    // If not repeated start, send stop.
    if (stop) {
        while(!obj->i2c->EVENTS_STOPPED){
        }
        obj->i2c->EVENTS_STOPPED = 0;
    }    
    return length;
}

int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
    int status, errorResult;
    obj->i2c->ADDRESS       = (address>>1);
    obj->i2c->SHORTS        = 0;
    obj->i2c->TASKS_STARTTX = 1;   
 
    for (int i=0; i<length; i++) {
        status = i2c_do_write(obj, data[i]);
        if(status) {
            i2c_reset(obj);
            errorResult = checkError(obj);
            if(errorResult<0){
                return errorResult;
            }
            return i;
        }
    }
    
    // If not repeated start, send stop.
    if (stop) {
        if(i2c_stop(obj)){
            return I2C_ERROR_NO_SLAVE;
        }
    }
    return length;
}

int i2c_byte_read(i2c_t *obj, int last) {
    char data;
    int status;
    
    status = i2c_do_read(obj,&data, last);
    if (status) {
        i2c_reset(obj);
    }
    return data;
}

int i2c_byte_write(i2c_t *obj, int data) {
    int status = 0;
    if(!addrSet){
        addrSet = 1;
        obj->i2c->ADDRESS = (data>>1);
        
        if(data&1){
            obj->i2c->EVENTS_RXDREADY = 0;
            obj->i2c->TASKS_STARTRX   = 1;
        }
        else{
            obj->i2c->TASKS_STARTTX   = 1;    
        }
    }
    else{
        status = i2c_do_write(obj, data);
        if(status) {
            i2c_reset(obj);
        }
    }
    return (1-status);
}