Diff: CN0216.cpp

Revision:

0:afcb81077332

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/CN0216.cpp	Wed May 18 15:18:08 2016 +0000
@@ -0,0 +1,161 @@
+/**
+*   @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);
+}
+