ADS1118.h

#ifndef ADS1118_h
#define ADS1118_h

#include "Arduino.h"
#include <SPI.h>

union Config {
    struct {                    
        uint8_t reserved:1;     
        uint8_t noOperation:2;  
        uint8_t pullUp:1;       
        uint8_t sensorMode:1;   
        uint8_t rate:3;         
        uint8_t operatingMode:1;
        uint8_t pga:3;          
        uint8_t mux:3;          
        uint8_t singleStart:1;  
    } bits;
    uint16_t word;              
    struct {
        uint8_t lsb;            
        uint8_t msb;            
    } byte;                     
};


class ADS1118 {
    public:
        ADS1118(uint8_t io_pin_cs);         
        void begin();                       
        double getTemperature();            
        uint16_t getADCValue(uint8_t inputs);                   
        double getMilliVolts(uint8_t inputs);                   
        double getMilliVolts();             
        void decodeConfigRegister(union Config configRegister); 
        void setSampligRate(uint8_t samplingRate);              
        void setFullScaleRange(uint8_t fsr);
        void setContinuousMode();           
        void setSingleShotMode();           
        void disablePullup();               
        void enablePullup();                
        void setInputSelected(uint8_t input);
        //Input multiplexer configuration selection for bits "MUX"
            //Differential inputs
        const uint8_t DIFF_0_1    = 0b000;  
        const uint8_t DIFF_0_3    = 0b001;  
        const uint8_t DIFF_1_3    = 0b010;  
        const uint8_t DIFF_2_3    = 0b011;  
            //Single ended inputs
        const uint8_t AIN_0       = 0b100;  
        const uint8_t AIN_1       = 0b101;  
        const uint8_t AIN_2       = 0b110;  
        const uint8_t AIN_3       = 0b111;  
        union Config configRegister;        

        //Bit constants
        const uint16_t SCLK       = 2000000;
        
        // Used by "SS" bit
        const uint8_t START_NOW   = 1;      
        
        // Used by "TS_MODE" bit
        const uint8_t ADC_MODE    = 0;      
        const uint8_t TEMP_MODE   = 1;      
        
        // Used by "MODE" bit
        const uint8_t CONTINUOUS  = 0;      
        const uint8_t SINGLE_SHOT = 1;      
        
        // Used by "PULL_UP_EN" bit
        const uint8_t PULLUP      = 1;      
        const uint8_t NO_PULLUP   = 0;      
        
        // Used by "NOP" bits
        const uint8_t VALID_CFG   = 0b01;   
        const uint8_t NO_VALID_CFG= 0b00;   
        
        // Used by "Reserved" bit
        const uint8_t RESERVED    = 1;      

        /*Full scale range (FSR) selection by "PGA" bits. 
         [Warning: this could increase the noise and the effective number of bits (ENOB). See tables above]*/
        const uint8_t FSR_6144    = 0b000;  
        const uint8_t FSR_4096    = 0b001;  
        const uint8_t FSR_2048    = 0b010;  
        const uint8_t FSR_1024    = 0b011;  
        const uint8_t FSR_0512    = 0b100;  
        const uint8_t FSR_0256    = 0b111;  

        /*Sampling rate selection by "DR" bits. 
        [Warning: this could increase the noise and the effective number of bits (ENOB). See tables above]*/
        const uint8_t RATE_8SPS   = 0b000;  
        const uint8_t RATE_16SPS  = 0b001;  
        const uint8_t RATE_32SPS  = 0b010;  
        const uint8_t RATE_64SPS  = 0b011;  
        const uint8_t RATE_128SPS = 0b100;  
        const uint8_t RATE_250SPS = 0b101;  
        const uint8_t RATE_475SPS = 0b110;  
        const uint8_t RATE_860SPS = 0b111;  
        
private:
        uint8_t lastSensorMode=3;           
        uint8_t cs;                         
        const float pgaFSR[8] = {6.144, 4.096, 2.048, 1.024, 0.512, 0.256, 0.256, 0.256};
        const uint8_t CONV_TIME[8]={125, 63, 32, 16, 8, 4, 3, 2};   

/*
                            Table 1. Noise in μVRMS (μVPP) at VDD = 3.3 V   [1]
                                DATA RATE FSR (Full-Scale Range)
  (SPS) ±6.144 V        ±4.096 V     ±2.048 V       ±1.024 V        ±0.512 V        ±0.256 V
    8   187.5 (187.5)   125 (125)    62.5 (62.5)    31.25 (31.25)   15.62 (15.62)   7.81 (7.81)
    16  187.5 (187.5)   125 (125)    62.5 (62.5)    31.25 (31.25)   15.62 (15.62)   7.81 (7.81)
    32  187.5 (187.5)   125 (125)    62.5 (62.5)    31.25 (31.25)   15.62 (15.62)   7.81 (7.81)
    64  187.5 (187.5)   125 (125)    62.5 (62.5)    31.25 (31.25)   15.62 (15.62)   7.81 (7.81)
    128 187.5 (187.5)   125 (125)    62.5 (62.5)    31.25 (31.25)   15.62 (15.62)   7.81 (12.35)
    250 187.5 (252.09)  125 (148.28) 62.5 (84.03)   31.25 (39.54)   15.62 (16.06)   7.81 (18.53)
    475 187.5 (266.92)  125 (227.38) 62.5 (79.08)   31.25 (56.84)   15.62 (32.13)   7.81 (25.95)
    860 187.5 (430.06)  125 (266.93) 62.5 (118.63)  31.25 (64.26)   15.62 (40.78)   7.81 (35.83)

    
            Table 2. ENOB from RMS Noise (Noise-Free Bits from Peak-to-Peak Noise) at VDD = 3.3 V
                                DATA RATE FSR (Full-Scale Range)
  (SPS)     ±6.144 V    ±4.096 V     ±2.048 V       ±1.024 V        ±0.512 V        ±0.256 V
    8       16 (16)     16 (16)      16 (16)        16 (16)         16 (16)         16 (16)
    16      16 (16)     16 (16)      16 (16)        16 (16)         16 (16)         16 (16)
    32      16 (16)     16 (16)      16 (16)        16 (16)         16 (16)         16 (16)
    64      16 (16)     16 (16)      16 (16)        16 (16)         16 (16)         16 (16)
    128     16 (16)     16 (16)      16 (16)        16 (16)         16 (16)         16 (15.33)
    250     16 (15.57)  16 (15.75)   16 (15.57)     16 (15.66)      16 (15.96)      16 (14.75)
    475     16 (15.49)  16 (15.13)   16 (15.66)     16 (15.13)      16 (14.95)      16 (14.26)
    860     16 (14.8)   16 (14.9)    16 (15.07)     16 (14.95)      16 (14.61)      16 (13.8)
    
    
    [1] Texas Instruments, "ADS1118 Ultrasmall, Low-Power, SPI™-Compatible, 16-Bit Analog-to-Digital 
    Converter with Internal Reference and Temperature Sensor", ADS1118 datasheet, SBAS457E [OCTOBER 2010–REVISED OCTOBER 2015]. 
    
    Note: This information is taken from http://www.ti.com
          Copyright © 2010–2015, Texas Instruments Incorporated
*/      

};

#endif