MeshCoreTel-firmware/variants/t1000-e/t1000e_sensors.cpp

#include <Arduino.h>
#include "t1000e_sensors.h"

#define HEATER_NTC_BX       4250    // thermistor coefficient B
#define HEATER_NTC_RP       8250    // ohm, series resistance to thermistor
#define HEATER_NTC_KA       273.15  // 25 Celsius at Kelvin
#define NTC_REF_VCC         3000    // mV, output voltage of LDO
#define LIGHT_REF_VCC       2400    // 
 
static unsigned int ntc_res2[136]={    
    113347,107565,102116,96978,92132,87559,83242,79166,75316,71677,
    68237,64991,61919,59011,56258,53650,51178,48835,46613,44506,
    42506,40600,38791,37073,35442,33892,32420,31020,29689,28423,
    27219,26076,24988,23951,22963,22021,21123,20267,19450,18670,                               
    17926,17214,16534,15886,15266,14674,14108,13566,13049,12554,
    12081,11628,11195,10780,10382,10000,9634,9284,8947,8624,
    8315,8018,7734,7461,7199,6948,6707,6475,6253,6039,
    5834,5636,5445,5262,5086,4917,4754,4597,4446,4301,
    4161,4026,3896,3771,3651,3535,3423,3315,3211,3111,
    3014,2922,2834,2748,2666,2586,2509,2435,2364,2294,
    2228,2163,2100,2040,1981,1925,1870,1817,1766,1716,
    1669,1622,1578,1535,1493,1452,1413,1375,1338,1303,
    1268,1234,1202,1170,1139,1110,1081,1053,1026,999,
    974,949,925,902,880,858,
};
 
static char ntc_temp2[136]=
{
    -30,-29,-28,-27,-26,-25,-24,-23,-22,-21,
    -20,-19,-18,-17,-16,-15,-14,-13,-12,-11,
    -10,-9,-8,-7,-6,-5,-4,-3,-2,-1,
    0,1,2,3,4,5,6,7,8,9,
    10,11,12,13,14,15,16,17,18,19,
    20,21,22,23,24,25,26,27,28,29,
    30,31,32,33,34,35,36,37,38,39,
    40,41,42,43,44,45,46,47,48,49,
    50,51,52,53,54,55,56,57,58,59,
    60,61,62,63,64,65,66,67,68,69,
    70,71,72,73,74,75,76,77,78,79,
    80,81,82,83,84,85,86,87,88,89,
    90,91,92,93,94,95,96,97,98,99,
    100,101,102,103,104,105,
};

static float get_heater_temperature( unsigned int vcc_volt, unsigned int ntc_volt )
{
    int i = 0;
    float Vout = 0, Rt = 0, temp = 0;
    Vout = ntc_volt;
    
    Rt = ( HEATER_NTC_RP * vcc_volt ) / Vout - HEATER_NTC_RP;   
        
    for( i = 0; i < 136; i++ )
    {
        if( Rt >= ntc_res2[i] )
        {
           break; 
        }
    }
 
    temp = ntc_temp2[i - 1] + 1 * ( ntc_res2[i - 1] - Rt ) / ( float )( ntc_res2[i - 1] - ntc_res2[i] );
 
    temp = ( temp * 100 + 5 ) / 100;
    return temp;
}

static int get_light_lv( unsigned int light_volt )
{  
    float Vout = 0, Vin = 0, Rt = 0, temp = 0;
    unsigned int light_level = 0;     
    
    if( light_volt <= 80 )
    {
        light_level = 0;
        return light_level;
    }
    else if( light_volt >= 2480 )
    {
        light_level = 100;
        return light_level;    
    }
    Vout = light_volt;
    light_level = 100 * ( Vout - 80 ) / LIGHT_REF_VCC;
   
    return light_level;
} 

float t1000e_get_temperature( void )
{
    unsigned int ntc_v, vcc_v;

    digitalWrite(PIN_3V3_EN, HIGH);
    digitalWrite(SENSOR_EN, HIGH);
    analogReference(AR_INTERNAL_3_0);
    analogReadResolution(12);
    delay(10);
    vcc_v = (1000.0*(analogRead(BATTERY_PIN) * ADC_MULTIPLIER * AREF_VOLTAGE)) / 4096;
    ntc_v = (1000.0 * AREF_VOLTAGE * analogRead(TEMP_SENSOR)) / 4096;
    digitalWrite(PIN_3V3_EN, LOW);
    digitalWrite(SENSOR_EN, LOW);

    return get_heater_temperature (vcc_v, ntc_v);
}

uint32_t t1000e_get_light( void )
{
    int lux = 0;
    unsigned int lux_v = 0;
 
    digitalWrite(SENSOR_EN, HIGH);
    analogReference(AR_INTERNAL_3_0);
    analogReadResolution(12);
    delay(10);
    lux_v = 1000 * analogRead(LUX_SENSOR) * AREF_VOLTAGE / 4096;
    lux = get_light_lv( lux_v );
    digitalWrite(SENSOR_EN, LOW);
 
    return lux;
}