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smaller temp calc

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This commit is contained in:
Moritz Ruffer 2025-03-26 18:17:39 +01:00
parent 11d5ccb2d3
commit 29a48d22a7
1 changed files with 8 additions and 17 deletions
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25
AMS_Master_Code/Core/Inc/NTC.h
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@ -4,24 +4,15 @@
#define NTC_B1 0.000300131f #define NTC_B1 0.000300131f
#define NTC_C1 5.08516E-06f #define NTC_C1 5.08516E-06f
#define NTC_D1 2.18765E-07f #define NTC_D1 2.18765E-07f
#define NTC_R25 10000.0f // 10k ohm at 25C
#define NTC_R_DIVIDER 10000.0f #define VREF 3000.0
#define NTC_V_DIVIDER 3.000f // 3V
[[gnu::always_inline]] // More efficient (?) calc using:
static inline float ntc_ohms_to_celsius(float ohms) { // R_T = R_Pullup / (V_REF / ADC - 1)
float log_ohms = logf(ohms / NTC_R25); // With R_T/R_0 and R_0 = R_T@25C
// R_T/R_0 = 1 / V_REF / ADC - 1
static inline int ntc_mv_to_celsius(int16_t adc) {
float log_ohms = logf(1/((VREF/adc)-1));
return 1.0f / (NTC_A1 + NTC_B1 * log_ohms + NTC_C1 * log_ohms * log_ohms + NTC_D1 * log_ohms * log_ohms * log_ohms) - 273.15f; return 1.0f / (NTC_A1 + NTC_B1 * log_ohms + NTC_C1 * log_ohms * log_ohms + NTC_D1 * log_ohms * log_ohms * log_ohms) - 273.15f;
}
[[gnu::always_inline]]
static inline float ohms_from_ntc_v(float v) {
return (NTC_R_DIVIDER * v) / (NTC_V_DIVIDER - v);
}
[[maybe_unused]]
static int ntc_mv_to_celsius(int mv) {
float v = (float)mv * 0.001f;
return (int)ntc_ohms_to_celsius(ohms_from_ntc_v(v));
} }