Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board
LTC2305.cpp
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1 /*!
2 LTC2305: 2-channel, 12-Bit SAR ADC with I2C interface
3 
4 @verbatim
5 
6 The LTC2305 is a low noise, low power, 8-channel, 12-bit successive
7 approximation ADC with an I2C compatible serial interface. This ADC includes an
8 internal reference and a fully differential sample-and-hold circuit to reduce
9 common mode noise. The LTC2305 operates from an internal clock to achieve a fast
10 1.3 microsecond conversion time.
11 
12 The LTC2305 operates from a single 5V supply and draws just 300 microamps at a
13 throughput rate of 1ksps. The ADC enters nap mode when not converting, reducing
14 the power dissipation.
15 
16 @endverbatim
17 
18 http://www.linear.com/product/LTC2305
19 
20 http://www.linear.com/product/LTC2305#demoboards
21 
22 
23 Copyright 2018(c) Analog Devices, Inc.
24 
25 All rights reserved.
26 
27 Redistribution and use in source and binary forms, with or without
28 modification, are permitted provided that the following conditions are met:
29  - Redistributions of source code must retain the above copyright
30  notice, this list of conditions and the following disclaimer.
31  - Redistributions in binary form must reproduce the above copyright
32  notice, this list of conditions and the following disclaimer in
33  the documentation and/or other materials provided with the
34  distribution.
35  - Neither the name of Analog Devices, Inc. nor the names of its
36  contributors may be used to endorse or promote products derived
37  from this software without specific prior written permission.
38  - The use of this software may or may not infringe the patent rights
39  of one or more patent holders. This license does not release you
40  from the requirement that you obtain separate licenses from these
41  patent holders to use this software.
42  - Use of the software either in source or binary form, must be run
43  on or directly connected to an Analog Devices Inc. component.
44 
45 THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
46 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
47 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
48 IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
49 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
50 LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
51 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
52 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
53 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
54 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
55 */
56 
57 //! @ingroup Analog_to_Digital_Converters
58 //! @{
59 //! @defgroup LTC2305 LTC2305: 2-channel, 12-Bit SAR ADC with I2C interface
60 //! @}
61 
62 /*! @file
63  @ingroup LTC2305
64  Library for LTC2305: 2-channel, 12-Bit SAR ADC with I2C interface
65 */
66 
67 #include <Arduino.h>
68 #include <stdint.h>
69 #include "Linduino.h"
70 #include "LT_I2C.h"
71 #include "LTC2305.h"
72 #include <Wire.h>
73 
74 // Commands
75 // Construct a channel / uni/bipolar by bitwise ORing one choice from the channel configuration
76 // and one choice from the command.
77 
78 // Example - read channel 3 single-ended
79 // adc_command = LTC2305_CH3 | LTC2305_UNIPOLAR_MODE;
80 
81 // Example - read voltage between channels 5 and 4 with 4 as positive polarity and in bipolar mode.
82 // adc_command = LTC2305_P4_N5 | LTC2305_BIPOLAR_MODE;
83 
84 
85 // Reads 12 bits in binary format
86 int8_t LTC2305_read(uint8_t i2c_address, uint8_t adc_command, uint16_t *ptr_adc_code)
87 {
88  int8_t ack = 0;
90 
91  data.LT_byte[1] = 0;
92  data.LT_byte[0] = 0;
93 
94  ack = i2c_read_word_data(i2c_address, adc_command, &data.LT_uint16);
95 
96  *ptr_adc_code = data.LT_uint16; //note the 12 bits of data are left justified
97 
98  return(ack);
99 }
100 
101 
102 // Calculates the LTC2305 input unipolar voltage.
103 float LTC2305_code_to_voltage(uint16_t adc_code, float vref, uint8_t uni_bipolar)
104 {
105  float voltage;
106  float sign = 1;
107 
108  if (uni_bipolar == LTC2305_UNIPOLAR_MODE)
109  {
110  voltage = (float)adc_code;
111  voltage = voltage / (pow(2,16)-1); //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
112  }
113  else
114  {
115  vref = vref/2;
116  if ((adc_code & 0x8000) == 0x8000) //adc code is < 0
117  {
118  adc_code = (adc_code ^ 0xFFFF)+1; //! Convert ADC code from two's complement to binary
119  sign = -1;
120  }
121  voltage = sign*(float)adc_code;
122  voltage = voltage / (pow(2,15)-1); //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
123  }
124  voltage = voltage * vref; //! 3) Multiply fraction by Vref to get the actual voltage at the input (in volts)
125 
126 
127  return(voltage);
128 }
uint8_t i2c_address
static uint8_t adc_command
Definition: DC2071AA.ino:111
static uint8_t uni_bipolar
Default set for unipolar mode.
Definition: DC682A.ino:121
Header File for Linduino Libraries and Demo Code.
int8_t LTC2305_read(uint8_t i2c_address, uint8_t adc_command, uint16_t *ptr_adc_code)
Reads 12-bit code from LTC2305, programs channel and mode for next conversion.
Definition: LTC2305.cpp:86
union LT_union_int32_4bytes data
Definition: DC2094A.ino:138
float LTC2305_code_to_voltage(uint16_t adc_code, float vref, uint8_t uni_bipolar)
Calculates the LTC2305 input voltage.
Definition: LTC2305.cpp:103
uint16_t LT_uint16
16-bit unsigned integer to be converted to two bytes
Definition: Linduino.h:102
int8_t i2c_read_word_data(uint8_t address, uint8_t command, uint16_t *value)
Read a 16-bit word of data from register specified by "command".
Definition: LT_I2C.cpp:172
LT_I2C: Routines to communicate with ATmega328P&#39;s hardware I2C port.
#define LTC2305_UNIPOLAR_MODE
Definition: LTC2305.h:130
This union splits one int16_t (16-bit signed integer) or uint16_t (16-bit unsigned integer) into two ...
Definition: Linduino.h:99
static float voltage
Definition: DC2289AA.ino:71
uint8_t LT_byte[2]
2 bytes (unsigned 8-bit integers) to be converted to a 16-bit signed or unsigned integer ...
Definition: Linduino.h:103
static uint32_t adc_code
Definition: DC2071AA.ino:113
LTC2305: 8-channel, 12-Bit SAR ADC with I2C interface.