128 lines
3.3 KiB
C++
128 lines
3.3 KiB
C++
#include "Arduino.h"
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#include "HermitCrab.h"
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#include "NTC_10K.h"
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#include "Config.h"
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const float resistance[] = {
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3360850.37, // -40°C
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1973470.32, // -35°C
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1179560.43, // -30°C
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718858.73, // -25°C
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445267.47, // -20°C
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281046.96, // -15°C
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180321.36, // -10°C
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117081.11, // -5°C
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77147.90, // 0°C
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51471.97, // 5°C
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34838.43, // 10°C
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23847.63, // 15°C
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16594.38, // 20°C
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12307.39, // 21°C
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11739.87, // 22°C
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11203.64, // 23°C
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10696.86, // 24°C
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10217.84, // 25°C
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9527.52, // 26°C
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9076.66, // 27°C
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8656.02, // 28°C
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8263.81, // 29°C
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7897.84, // 30°C
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5868.86, // 35°C
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4383.72, // 40°C
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3315.12, // 45°C
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2527.73, // 50°C
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1942.15, // 55°C
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1505.11, // 60°C
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1174.71, // 65°C
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926.23, // 70°C
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735.99, // 75°C
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588.91, // 80°C
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474.43, // 85°C
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384.48, // 90°C
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313.88, // 95°C
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258.87, // 100°C
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215.64, // 105°C
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181.10, // 110°C
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153.01, // 115°C
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129.77, // 120°C
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110.27, // 125°C
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94.03, // 130°C
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80.13, // 135°C
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68.18, // 140°C
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57.99, // 145°C
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49.30 // 150°C
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};
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const int16_t temp_C[] = {
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-40, -35, -30, -25, -20, -15, -10, -5, 0, 5, 10, 15,
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20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
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35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100,
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105, 110, 115, 120, 125, 130, 135, 140, 145, 150 };
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NTC_10K ntc;
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void NTC_10K::setup(bool bNegativePolarity) {
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m_bNegativePolarity = bNegativePolarity;
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_vRef = 3.3f;
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_RESO = 4095;
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for (int i = 0; i < 16; i++) temps[i] = 0;
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temp_idx = 0;
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temp_sum = 0;
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pinMode(PIN_NTC, INPUT); // Set PIN_NTC as input
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analogReadResolution(12); // Set ADC resolution to 12 bits (0-4095)
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analogSetAttenuation(ADC_11db); // Set attenuation for full-scale 3.3V
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}
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void NTC_10K::readSensor() {
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float Vin;
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int16_t temp;
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static int16_t lastTemp = 0;
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int adcValue = analogRead(PIN_NTC); // Read ADC value from PIN_NTC
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// Calculate the input voltage from the ADC reading
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Vin = (float)adcValue * _vRef / _RESO;
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// Calculate the resistance of the thermistor
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// Calculate the resistance of the thermistor (adjusted for inverted ADC behavior)
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float r;
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if (m_bNegativePolarity) {
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// NTC is connected to Negative
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r = (Vin / (_vRef - Vin)) * rRef;
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} else {
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// NTC is connected to Positive
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r = ((_vRef - Vin) / Vin) * rRef;
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}
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// Find the index of the resistance in the table where r is between resistance[i-1] and resistance[i]
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int i = 0;
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while (i < sizeof(resistance) / sizeof(resistance[0]) - 1 && resistance[i] > r) {
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i++;
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}
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// If r is out of range, return the closest extreme temperature
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if (i == 0 || i == sizeof(resistance) / sizeof(resistance[0]) - 1) {
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if (lastTemp != 0) temp = lastTemp;
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else temp = 0;
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}
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else {
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// Interpolate between resistance[i-1] and resistance[i]
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float m = (temp_C[i] - temp_C[i - 1]) / (resistance[i] - resistance[i - 1]); // Slope
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float b = temp_C[i - 1] - (m * resistance[i - 1]); // Intercept
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temp = (int16_t) roundf((m * r + b) * 10.0f);
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}
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// Return the temperature as an integer scaled by 10 (e.g., 25.3°C => 253)
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temp_sum -= temps[temp_idx];
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temps[temp_idx++] = temp;
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temp_idx &= NTC_MASK;
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temp_sum += temp;
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lastTemp = temp;
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m_nTemp = temp_sum / NTC_COUNT;
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}
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