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[ms5611] Re-implement conversion from ADC readings to sensor values (#2665)

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anatoly-savchenkov
2021-11-11 00:01:47 +03:00
committed by GitHub
parent 5ff7c8418c
commit f310cacd41
1 changed files with 35 additions and 17 deletions
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52
esphome/components/ms5611/ms5611.cpp
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@@ -75,30 +75,48 @@ void MS5611Component::read_pressure_(uint32_t raw_temperature) {
const uint32_t raw_pressure = (uint32_t(bytes[0]) << 16) | (uint32_t(bytes[1]) << 8) | (uint32_t(bytes[2])); const uint32_t raw_pressure = (uint32_t(bytes[0]) << 16) | (uint32_t(bytes[1]) << 8) | (uint32_t(bytes[2]));
this->calculate_values_(raw_temperature, raw_pressure); this->calculate_values_(raw_temperature, raw_pressure);
} }
// Calculations are taken from the datasheet which can be found here:
// https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+Sheet%7FMS5611-01BA03%7FB3%7Fpdf%7FEnglish%7FENG_DS_MS5611-01BA03_B3.pdf%7FCAT-BLPS0036
// Sections PRESSURE AND TEMPERATURE CALCULATION and SECOND ORDER TEMPERATURE COMPENSATION
// Variable names below match variable names from the datasheet but lowercased
void MS5611Component::calculate_values_(uint32_t raw_temperature, uint32_t raw_pressure) { void MS5611Component::calculate_values_(uint32_t raw_temperature, uint32_t raw_pressure) {
const int32_t d_t = int32_t(raw_temperature) - (uint32_t(this->prom_[4]) << 8); const uint32_t c1 = uint32_t(this->prom_[0]);
float temperature = (2000 + (int64_t(d_t) * this->prom_[5]) / 8388608.0f) / 100.0f; const uint32_t c2 = uint32_t(this->prom_[1]);
const uint16_t c3 = uint16_t(this->prom_[2]);
const uint16_t c4 = uint16_t(this->prom_[3]);
const int32_t c5 = int32_t(this->prom_[4]);
const uint16_t c6 = uint16_t(this->prom_[5]);
const uint32_t d1 = raw_pressure;
const int32_t d2 = raw_temperature;
float pressure_offset = (uint32_t(this->prom_[1]) << 16) + ((this->prom_[3] * d_t) >> 7); // Promote dt to 64 bit here to make the math below cleaner
float pressure_sensitivity = (uint32_t(this->prom_[0]) << 15) + ((this->prom_[2] * d_t) >> 8); const int64_t dt = d2 - (c5 << 8);
int32_t temp = (2000 + ((dt * c6) >> 23));
if (temperature < 20.0f) { int64_t off = (c2 << 16) + ((dt * c4) >> 7);
const float t2 = (d_t * d_t) / 2147483648.0f; int64_t sens = (c1 << 15) + ((dt * c3) >> 8);
const float temp20 = (temperature - 20.0f) * 100.0f;
float pressure_offset_2 = 2.5f * temp20 * temp20; if (temp < 2000) {
float pressure_sensitivity_2 = 1.25f * temp20 * temp20; const int32_t t2 = (dt * dt) >> 31;
if (temp20 < -15.0f) { int32_t off2 = ((5 * (temp - 2000) * (temp - 2000)) >> 1);
const float temp15 = (temperature + 15.0f) * 100.0f; int32_t sens2 = ((5 * (temp - 2000) * (temp - 2000)) >> 2);
pressure_offset_2 += 7.0f * temp15; if (temp < -1500) {
pressure_sensitivity_2 += 5.5f * temp15; off2 = (off2 + 7 * (temp + 1500) * (temp + 1500));
sens2 = sens2 + ((11 * (temp + 1500) * (temp + 1500)) >> 1);
} }
temperature -= t2; temp = temp - t2;
pressure_offset -= pressure_offset_2; off = off - off2;
pressure_sensitivity -= pressure_sensitivity_2; sens = sens - sens2;
} }
const float pressure = ((raw_pressure * pressure_sensitivity) / 2097152.0f - pressure_offset) / 3276800.0f; // Here we multiply unsigned 32-bit by signed 64-bit using signed 64-bit math.
// Possible ranges of D1 and SENS from the datasheet guarantee
// that this multiplication does not overflow
const int32_t p = ((((d1 * sens) >> 21) - off) >> 15);
const float temperature = temp / 100.0f;
const float pressure = p / 100.0f;
ESP_LOGD(TAG, "Got temperature=%0.02f°C pressure=%0.01fhPa", temperature, pressure); ESP_LOGD(TAG, "Got temperature=%0.02f°C pressure=%0.01fhPa", temperature, pressure);
if (this->temperature_sensor_ != nullptr) if (this->temperature_sensor_ != nullptr)