Linduino  1.3.0
Linear Technology Arduino-Compatible Demonstration Board
LTM2893.cpp
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1 /*!
2 LTM2893-1: 100MHz ADC SPI Isolator
3 
4 @verbatim
5 
6 @endverbatim
7 
8 http://www.linear.com/product/LTM2893
9 
10 http://www.linear.com/product/LTM2893#demoboards
11 
12 
13 
14 Copyright 2018(c) Analog Devices, Inc.
15 
16 All rights reserved.
17 
18 Redistribution and use in source and binary forms, with or without
19 modification, are permitted provided that the following conditions are met:
20  - Redistributions of source code must retain the above copyright
21  notice, this list of conditions and the following disclaimer.
22  - Redistributions in binary form must reproduce the above copyright
23  notice, this list of conditions and the following disclaimer in
24  the documentation and/or other materials provided with the
25  distribution.
26  - Neither the name of Analog Devices, Inc. nor the names of its
27  contributors may be used to endorse or promote products derived
28  from this software without specific prior written permission.
29  - The use of this software may or may not infringe the patent rights
30  of one or more patent holders. This license does not release you
31  from the requirement that you obtain separate licenses from these
32  patent holders to use this software.
33  - Use of the software either in source or binary form, must be run
34  on or directly connected to an Analog Devices Inc. component.
35 
36 THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
37 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
38 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
39 IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
40 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41 LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
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43 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
44 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
45 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
46 */
47 
48 //! @ingroup Analog_to_Digital_Converters
49 //! @{
50 //! @defgroup LTM2893 LTM2893: Isolator for 1Msps ADC
51 //! @}
52 
53 /*! @file
54  @ingroup LTM2893
55  Library for LTM2893: Isolator for 16/18-Bit 1Msps ADC
56 */
57 
58 #include <Arduino.h>
59 #include <stdint.h>
60 #include "Linduino.h"
61 #include "LT_SPI.h"
62 #include "LTM2893.h"
63 #include <SPI.h>
64 
65 
66 // Reads from a SPI LTM2893-XX device that has no configuration word and a 20 bit output word in 2's complement format.
67 void LTM2893_read(uint8_t cs, int32_t *ptr_adc_code)
68 {
69  LT_union_int16_2bytes command; // LTM2893 data and command
70  command.LT_uint16 = 0; // Set to zero, not necessary but avoids
71  // random data in scope shots.
72 
73 //Form a four byte object to hold four bytes of data
74  LT_union_int32_4bytes data; //instantiate the union
75  data.LT_byte[3] = 0;
76  data.LT_byte[2] = 0;
77  data.LT_byte[1] = 0;
78  data.LT_byte[0] = 0;
79 
80  spi_transfer_block(cs,command.LT_byte,data.LT_byte,3); // read 3 bytes 2893 is setup as 24 bits. overreading will cause a fault.
81 
82  *ptr_adc_code = data.LT_int32;
83 
84  return;
85 }
86 
87 void LTM2893_config(uint8_t user_config)
88 {
89  uint8_t *rx_data;
90  spi_transfer_byte(LTM2893_CSC_PIN,user_config,rx_data);
91 }
92 
93 
94 // Calculates the voltage corresponding to an adc code in 2's complement, given the reference voltage (in volts)
95 /*
96 float LTM2893_code_to_voltage(int32_t adc_code, float vref)
97 {
98  float voltage;
99  if (adc_code >= pow(2,23)) {
100  voltage = (float)adc_code - pow(2,23);
101  voltage = voltage / (pow(2,22)-1); //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
102  voltage = voltage * -vref - (vref/pow(2,23)); //! 3) Multiply fraction by Vref to get the actual voltage at the input (in volts)
103  }
104  else {
105  voltage = (float)adc_code;
106  voltage = voltage / (pow(2,22)-1); //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
107  voltage = voltage * vref; //! 3) Multiply fraction by Vref to get the actual voltage at the input (in volts)
108  }
109  return(voltage);
110 }
111 */
112 float LTM2893_code_to_voltage(int32_t adc_code, float vref)
113 {
114  float voltage;
115  if (adc_code >= pow(2,23))
116  {
117  voltage = (float)adc_code - pow(2,24);
118  voltage = voltage / (pow(2,23)-1); //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
119  voltage = voltage * vref; //! 3) Multiply fraction by Vref to get the actual voltage at the input (in volts)
120  }
121  else
122  {
123  voltage = (float)adc_code;
124  voltage = voltage / (pow(2,23)-1); //! 2) This calculates the input as a fraction of the reference voltage (dimensionless)
125  voltage = voltage * vref; //! 3) Multiply fraction by Vref to get the actual voltage at the input (in volts)
126  }
127  return(voltage);
128 }
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
Header File for Linduino Libraries and Demo Code.
union LT_union_int32_4bytes data
Definition: DC2094A.ino:138
uint16_t LT_uint16
16-bit unsigned integer to be converted to two bytes
Definition: Linduino.h:102
int32_t LT_int32
32-bit signed integer to be converted to four bytes
Definition: Linduino.h:110
#define LTM2893_CSC_PIN
Definition: LTM2893.h:72
LT_SPI: Routines to communicate with ATmega328P&#39;s hardware SPI port.
This union splits one int32_t (32-bit signed integer) or uint32_t (32-bit unsigned integer) four uint...
Definition: Linduino.h:108
float LTM2893_code_to_voltage(int32_t adc_code, float vref)
Calculates the LTM2893 input voltage given the binary data and lsb weight.
Definition: LTM2893.cpp:112
This union splits one int16_t (16-bit signed integer) or uint16_t (16-bit unsigned integer) into two ...
Definition: Linduino.h:99
void LTM2893_config(uint8_t user_config)
Definition: LTM2893.cpp:87
void spi_transfer_byte(uint8_t cs_pin, uint8_t tx, uint8_t *rx)
Reads and sends a byte.
Definition: LT_SPI.cpp:87
void LTM2893_read(uint8_t cs, int32_t *ptr_adc_code)
Reads the LTM2893 and returns 32-bit data in 2&#39;s complement format.
Definition: LTM2893.cpp:67
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
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
LTM2893-1: 100MHz ADC SPI Isolator.
static uint32_t adc_code
Definition: DC2071AA.ino:113