obd_iso15765/BleCanBoxCode/NRF51802/components/drivers_ext/ds1624/ds1624.c

/* Copyright (c) 2012 Nordic Semiconductor. All Rights Reserved.
 *
 * The information contained herein is property of Nordic Semiconductor ASA.
 * Terms and conditions of usage are described in detail in NORDIC
 * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
 *
 * Licensees are granted free, non-transferable use of the information. NO
 * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
 * the file.
 *
 */
 
#include "ds1624.h"
#include "twi_master.h"
#include "nrf_delay.h"

/*lint ++flb "Enter library region" */

#define DS1634_BASE_ADDRESS 0x90 //!< 4 MSBs of the DS1624 TWI address

#define DS1624_ONESHOT_MODE    0x01 //!< Bit in configuration register for 1-shot mode 
#define DS1624_CONVERSION_DONE 0x80 //!< Bit in configuration register to indicate completed temperature conversion

static uint8_t m_device_address; //!< Device address in bits [7:1]

const uint8_t command_access_memory      = 0x17; //!< Reads or writes to 256-byte EEPROM memory
const uint8_t command_access_config      = 0xAC; //!< Reads or writes configuration data to configuration register 
const uint8_t command_read_temp          = 0xAA; //!< Reads last converted temperature value from temperature register
const uint8_t command_start_convert_temp = 0xEE; //!< Initiates temperature conversion.
const uint8_t command_stop_convert_temp  = 0x22; //!< Halts temperature conversion.

/**
 * @brief Function for reading the current configuration of the sensor.
 *
 * @return uint8_t Zero if communication with the sensor failed. Contents (always non-zero) of configuration register (@ref DS1624_ONESHOT_MODE and @ref DS1624_CONVERSION_DONE) if communication succeeded.
 */
static uint8_t ds1624_config_read(void)
{
    uint8_t config = 0;

    // Write: command protocol
    if (twi_master_transfer(m_device_address, (uint8_t*)&command_access_config, 1, TWI_DONT_ISSUE_STOP))
    {
        if (twi_master_transfer(m_device_address | TWI_READ_BIT, &config, 1, TWI_ISSUE_STOP)) // Read: current configuration
        {
            // Read succeeded, configuration stored to variable "config"
        }
        else
        {
            // Read failed
            config = 0;
        }
    }

    return config;
}

bool ds1624_init(uint8_t device_address)
{
    bool transfer_succeeded = true;
    m_device_address = DS1634_BASE_ADDRESS + (uint8_t)(device_address << 1);

    uint8_t config = ds1624_config_read();

    if (config != 0)
    {
        // Configure DS1624 for 1SHOT mode if not done so already.
        if (!(config & DS1624_ONESHOT_MODE))
        {
            uint8_t data_buffer[2];

            data_buffer[0] = command_access_config;
            data_buffer[1] = DS1624_ONESHOT_MODE;

            transfer_succeeded &= twi_master_transfer(m_device_address, data_buffer, 2, TWI_ISSUE_STOP);
        }
    }
    else
    {
        transfer_succeeded = false;
    }

    return transfer_succeeded;
}

bool ds1624_start_temp_conversion(void)
{
    return twi_master_transfer(m_device_address, (uint8_t*)&command_start_convert_temp, 1, TWI_ISSUE_STOP);
}

bool ds1624_is_temp_conversion_done(void)
{
    uint8_t config = ds1624_config_read();

    if (config & DS1624_CONVERSION_DONE)
    {
        return true;
    }
    else
    {
        return false;
    }
}

bool ds1624_temp_read(int8_t * temperature_in_celcius, int8_t * temperature_fraction)
{
    bool transfer_succeeded = false;

    // Write: Begin read temperature command
    if (twi_master_transfer(m_device_address, (uint8_t*)&command_read_temp, 1, TWI_DONT_ISSUE_STOP))
    {
        uint8_t data_buffer[2];

        // Read: 2 temperature bytes to data_buffer
        if (twi_master_transfer(m_device_address | TWI_READ_BIT, data_buffer, 2, TWI_ISSUE_STOP)) 
        {
            *temperature_in_celcius = (int8_t)data_buffer[0];
            *temperature_fraction   = (int8_t)data_buffer[1];

            transfer_succeeded = true;
        }
    }

    return transfer_succeeded;
}

/*lint --flb "Leave library region" */