File content as of revision 24:dae7123d432a:

/**
*   @file     cn0216.cpp
*   @brief    Source file for CN0216
*   @author   Analog Devices Inc.
*
* For support please go to:
* Github: https://github.com/analogdevicesinc/mbed-adi
* Support: https://ez.analog.com/community/linux-device-drivers/microcontroller-no-os-drivers
* Product: www.analog.com/EVAL-CN0216-ARDZ
* More: https://wiki.analog.com/resources/tools-software/mbed-drivers-all

********************************************************************************
* Copyright 2016(c) Analog Devices, Inc.
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*  - Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*  - Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*  - Neither the name of Analog Devices, Inc. nor the names of its
*    contributors may be used to endorse or promote products derived
*    from this software without specific prior written permission.
*  - The use of this software may or may not infringe the patent rights
*    of one or more patent holders.  This license does not release you
*    from the requirement that you obtain separate licenses from these
*    patent holders to use this software.
*  - Use of the software either in source or binary form, must be run
*    on or directly connected to an Analog Devices Inc. component.
*
* THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
********************************************************************************/

#include "mbed.h"
#include "AD7791.h"
#include "CN0216.h"
extern Serial pc;

/**
 * CN0216 constructor
 * @param CSAD7791 - Chipselect of the AD7791
 * @param MOSI - MOSI line of the SPI bus
 * @param MISO - MISO line of the SPI bus
 * @param SCK - SCK line of the SPI bus
 */
CN0216::CN0216(PinName CSAD7791, PinName MOSI, PinName MISO, PinName SCK) : ad7791(1.2, CSAD7791, MOSI, MISO, SCK)
{
    _cal_weight = 0;
    _zero_scale_value = 0;
    _full_scale_value = 0;
    _weight_units_per_bit = 0;
}

/**
 * Initializes the mode and filter values of the AD7791 and sets the weight to be used in calibration
 * @param cal_weight - weight used in calibration
 * @param mode_val - value of the mode register
 * @param filter_val - value of the filter register
 */
void CN0216::init(float cal_weight, uint8_t mode_val, uint8_t filter_val)
{
    _cal_weight = cal_weight;
    ad7791.frequency(500000);
    wait_ms(50);
    ad7791.reset();
    wait_ms(50);
    ad7791.write_mode_reg(mode_val);
    wait_us(2);
    ad7791.write_filter_reg(filter_val);
    wait_ms(50);
}

/**
 * Calibrates the CN0216 weigh scale
 * @param cal - calibration step.
 * Step CN0216::ZERO_SCALE_CALIBRATION will take CN0216::_NUMBER_OF_SAMPLES samples and use the minimum as value for the zero scale
 * Step CN0216::FULL_SCALE_CALIBRATION will take CN0216::_NUMBER_OF_SAMPLES samples and use the average as value for the full scale
 * Step COMPUTE_UNITS_PER_BIT will compute the grams per bit used in weight computation.
 */
void CN0216::calibrate(CalibrationStep_t cal)
{
    uint64_t sum = 0;
    uint32_t min = 0xFFFFFFFF;
    uint32_t sample = 0;
    switch(cal) {
        case ZERO_SCALE_CALIBRATION:
        case FULL_SCALE_CALIBRATION:
            for(int i = 0; i < _NUMBER_OF_SAMPLES; i++) {
                sample = ad7791.read_u32();
                min = (min < sample) ? min : sample;
                sum += ad7791.read_u32();
                wait_us(5);
            }
            if(cal == ZERO_SCALE_CALIBRATION) {
                // pc.printf("ZERO SCALE VALUE = %x",sum);
                _zero_scale_value = min;
            } else {
                //  pc.printf("FULL SCALE VALUE = %x",sum);
                sum = sum / _NUMBER_OF_SAMPLES;
                _full_scale_value = sum;
            }
            break;

        case COMPUTE_UNITS_PER_BIT:
            _weight_units_per_bit = _cal_weight / (static_cast<float> (_full_scale_value - _zero_scale_value));  /* Calculate number of grams per LSB */
            // pc.printf("GRAMS/LSB = %f", _grams_per_bit);
            break;
        default:
            break;
    }

}

/**
 * Computes the weight based on the formula
 * weight = (data - zeroscale) * weight_units_per_bit
 * @param data read from the ADC
 * @return weight based on data
 */
float CN0216::compute_weight(uint32_t data)
{
//	pc.printf("\r\nFULL_SCALE_VALUE = %x\r\nZERO_SCALE_VALUE = %x\r\nDATA READ = %x\r\nGRAMS/LSB = %f\r\n",_full_scale_value,data,_zero_scale_value,_grams_per_bit);
    if(data < _zero_scale_value)
        data = _zero_scale_value; // clamp data to 0
    float weight_in_grams =  (static_cast<float>((data) - _zero_scale_value)) * _weight_units_per_bit;         /* Calculate weight */
    return weight_in_grams;
}

/**
 * Reads the AD7791
 * @return value read by the ADC
 */
uint32_t CN0216::read_u32()
{
    return ad7791.read_u32();
}

/**
 * Reads the ADC and computes the weight based on the formula described above.
 * @return weight
 */
float CN0216::read_weight()
{
    uint32_t weight =  read_u32();
    return compute_weight(weight);
}