| Linduino 1.3.0 Linear Technology Arduino-Compatible Demonstration Board

LTC2418.cpp
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1 /*!
2 LTC2418: LTC2418 - 16-Channel 24-Bit No Latency Delta-Sigma ADC
3
4 @verbatim
5
6 The LTC2414/LTC2418 are 8-/16-channel (4-/8-differential) micropower 24-bit
7 delta-sigma analog-to-digital converters. They operate from 2.7V to 5.5V and
8 include an integrated oscillator, 2ppm INL and 0.2ppm RMS noise. They use
9 delta-sigma technology and provide single cycle settling time for multiplexed
10 applications. Through a single pin, the LTC2414/LTC2418 can be configured for
11 better than 110dB differential mode rejection at 50Hz or 60Hz +/-2%, or they can
12 be driven by an external oscillator for a user-defined rejection frequency. The
13 internal oscillator requires no external frequency setting components.
14
15 @endverbatim
16
17 http://www.linear.com/product/LTC2418
18
19 http://www.linear.com/product/LTC2418#demoboards
20
21
22 Copyright 2018(c) Analog Devices, Inc.
23
24 All rights reserved.
25
26 Redistribution and use in source and binary forms, with or without
27 modification, are permitted provided that the following conditions are met:
28 - Redistributions of source code must retain the above copyright
29 notice, this list of conditions and the following disclaimer.
30 - Redistributions in binary form must reproduce the above copyright
31 notice, this list of conditions and the following disclaimer in
32 the documentation and/or other materials provided with the
33 distribution.
34 - Neither the name of Analog Devices, Inc. nor the names of its
35 contributors may be used to endorse or promote products derived
36 from this software without specific prior written permission.
37 - The use of this software may or may not infringe the patent rights
38 of one or more patent holders. This license does not release you
39 from the requirement that you obtain separate licenses from these
40 patent holders to use this software.
41 - Use of the software either in source or binary form, must be run
42 on or directly connected to an Analog Devices Inc. component.
43
44 THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
45 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
46 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
47 IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
48 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
49 LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
50 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
51 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
52 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
53 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
54 */
55
56 //! @ingroup Analog_to_Digital_Converters
57 //! @{
58 //! @defgroup LTC2418 LTC2418: 16-Channel 24-Bit No Latency Delta-Sigma ADC
59 //! @}
60
61 /*! @file
62 @ingroup LTC2418
63 Library for LTC2418: 16-Channel 24-Bit No Latency Delta-Sigma ADC
64 */
65
66 #include <stdint.h>
67 #include <Arduino.h>
68 #include "Linduino.h"
69 #include "LT_SPI.h"
70 #include "LTC2418.h"
71 #include <SPI.h>
72
73 int8_t LTC2418_EOC_timeout(uint8_t cs, uint16_t miso_timeout)
74 // Checks for EOC with a specified timeout
75 {
76 uint16_t timer_count = 0; // Timer count for MISO
77 output_low(cs); //! 1) Pull CS low
78 while (1) //! 2) Wait for SDO (MISO) to go low
79 {
80 if (input(MISO) == 0) break; //! 3) If SDO is low, break loop
81 if (timer_count++>miso_timeout) // If timeout, return 1 (failure)
82 {
83 output_high(cs); // Pull CS high
84 return(1);
85 }
86 else
87 delay(1);
88 }
89 return(0);
90 }
91
92 void LTC2418_read(uint8_t cs, uint8_t adc_command, uint32_t *adc_code)
93 // Reads the LTC2418
94 {
95 LT_union_int32_4bytes data, command;
96 command.LT_byte[3] = adc_command;
97 command.LT_byte[2] = 0;
98 command.LT_byte[1] = 0;
99 command.LT_byte[0] = 0;
100
101 output_low(cs); //! 1) Pull CS low
102 spi_transfer_block(cs, command.LT_byte, data.LT_byte, (uint8_t)4); //! 2) Transfer 4 bytes
103 output_high(cs); //! 3) Pull CS high
104 *adc_code = data.LT_int32;
105 }
106
107 float LTC2418_code_to_voltage(int32_t adc_code, float LTC2418_lsb , int32_t LTC2418_offset_code)
108 // Calculates the LTC2418 input bipolar voltage
109 {
110 float adc_voltage;
111 adc_code = adc_code>>6; //! 1) Bit-shift ADC code to the right 6 bits
112 adc_code -= 8388608; //! 2) Convert ADC code from offset binary to binary
113 adc_voltage=((float)adc_code+LTC2418_offset_code)*(LTC2418_lsb); //! 3) Calculate voltage from ADC code, lsb, offset.
114 return(adc_voltage);
115 }
116
117 void LTC2418_cal_voltage(int32_t zero_code, int32_t fs_code, float zero_voltage, float fs_voltage, float *LTC2418_lsb , int32_t *LTC2418_offset_code)
118 // Calibrate the lsb
119 {
120 zero_code = zero_code >> 6; //! 1) Bit-shift zero code to the right 6 bits
121 zero_code -= 8388608; //! 2) Convert zero code from offset binary to binary
122 fs_code = fs_code >> 6; //! 3) Bit-shift full scale code to the right 6 bits
123 fs_code -= 8388608; //! 4) Convert full scale code from offset binary to binary
124
125 float temp_offset;
126 *LTC2418_lsb = (fs_voltage-zero_voltage)/((float)(fs_code - zero_code)); //! 5) Calculate the LSB
127
128 temp_offset = (zero_voltage/ *LTC2418_lsb) - zero_code; //! 6) Calculate Unipolar offset
129 temp_offset = (temp_offset > (floor(temp_offset) + 0.5)) ? ceil(temp_offset) : floor(temp_offset); //! 7) Round
130 *LTC2418_offset_code = (int32_t)temp_offset; //! 8) Cast as int32_t
131 }
adc_command
static uint8_t adc_command
Definition: DC2071AA.ino:111
LT_union_int32_4bytes::LT_byte
uint8_t LT_byte[4]
4 bytes (unsigned 8-bit integers) to be converted to a 32-bit signed or unsigned integer ...
Definition: Linduino.h:112
output_high
#define output_high(pin)
Set "pin" high.
Definition: Linduino.h:75
LTC2418_offset_code
static int32_t LTC2418_offset_code
Ideal offset for a perfect part.
Definition: DC571A.ino:114
LTC2418_cal_voltage
void LTC2418_cal_voltage(int32_t zero_code, int32_t fs_code, float zero_voltage, float fs_voltage, float *LTC2418_lsb, int32_t *LTC2418_offset_code)
Calibrate the lsb.
Definition: LTC2418.cpp:117
Linduino.h
Header File for Linduino Libraries and Demo Code.
adc_voltage
static float adc_voltage
Definition: DC2071AA.ino:115
data
union LT_union_int32_4bytes data
Definition: DC2094A.ino:138
LTC2418_lsb
static float LTC2418_lsb
Ideal LSB voltage for a perfect part.
Definition: DC571A.ino:113
LTC2418.h
LTC2418: 16-Channel 24-Bit No Latency Delta-Sigma ADC.
output_low
#define output_low(pin)
Set "pin" low.
Definition: Linduino.h:72
input
#define input(pin)
Return the state of pin "pin".
Definition: Linduino.h:79
LT_union_int32_4bytes::LT_int32
int32_t LT_int32
32-bit signed integer to be converted to four bytes
Definition: Linduino.h:110
LTC2418_code_to_voltage
float LTC2418_code_to_voltage(int32_t adc_code, float LTC2418_lsb, int32_t LTC2418_offset_code)
Calculates the LTC2418 input bipolar voltage.
Definition: LTC2418.cpp:107
LT_SPI.h
LT_SPI: Routines to communicate with ATmega328P&#39;s hardware SPI port.
LTC2418_EOC_timeout
int8_t LTC2418_EOC_timeout(uint8_t cs, uint16_t miso_timeout)
Checks for EOC with a specified timeout.
Definition: LTC2418.cpp:73
LT_union_int32_4bytes
This union splits one int32_t (32-bit signed integer) or uint32_t (32-bit unsigned integer) four uint...
Definition: Linduino.h:108
spi_transfer_block
void spi_transfer_block(uint8_t cs_pin, uint8_t *tx, uint8_t *rx, uint8_t length)
Reads and sends a byte array.
Definition: LT_SPI.cpp:125
adc_code
static uint32_t adc_code
Definition: DC2071AA.ino:113
LTC2418_read
void LTC2418_read(uint8_t cs, uint8_t adc_command, uint32_t *adc_code)
Reads the LTC2418 result and programs the configuration for the next conversion.
Definition: LTC2418.cpp:92