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Code Issues Releases Wiki Activity

[adc] Fix autorange negative coefficient bug causing incorrect voltage readings (#10549)

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This commit is contained in:
Edward Firmo
2025-09-09 02:56:18 +02:00
committed by GitHub
parent f6d69231e8
commit 90c2fdd565
1 changed files with 29 additions and 6 deletions
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35
esphome/components/adc/adc_sensor_esp32.cpp
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@@ -241,6 +241,8 @@ float ADCSensor::sample_autorange_() {
cali_config.bitwidth = ADC_BITWIDTH_DEFAULT;
err = adc_cali_create_scheme_curve_fitting(&cali_config, &handle);
ESP_LOGVV(TAG, "Autorange atten=%d: Calibration handle creation %s (err=%d)", atten,
(err == ESP_OK) ? "SUCCESS" : "FAILED", err);
#else
adc_cali_line_fitting_config_t cali_config = {
.unit_id = this->adc_unit_,
@@ -251,10 +253,14 @@ float ADCSensor::sample_autorange_() {
#endif
};
err = adc_cali_create_scheme_line_fitting(&cali_config, &handle);
ESP_LOGVV(TAG, "Autorange atten=%d: Calibration handle creation %s (err=%d)", atten,
(err == ESP_OK) ? "SUCCESS" : "FAILED", err);
#endif
int raw;
err = adc_oneshot_read(this->adc_handle_, this->channel_, &raw);
ESP_LOGVV(TAG, "Autorange atten=%d: Raw ADC read %s, value=%d (err=%d)", atten,
(err == ESP_OK) ? "SUCCESS" : "FAILED", raw, err);
if (err != ESP_OK) {
ESP_LOGW(TAG, "ADC read failed in autorange with error %d", err);
@@ -275,8 +281,10 @@ float ADCSensor::sample_autorange_() {
err = adc_cali_raw_to_voltage(handle, raw, &voltage_mv);
if (err == ESP_OK) {
voltage = voltage_mv / 1000.0f;
ESP_LOGVV(TAG, "Autorange atten=%d: CALIBRATED - raw=%d -> %dmV -> %.6fV", atten, raw, voltage_mv, voltage);
} else {
voltage = raw * 3.3f / 4095.0f;
ESP_LOGVV(TAG, "Autorange atten=%d: UNCALIBRATED FALLBACK - raw=%d -> %.6fV (3.3V ref)", atten, raw, voltage);
}
// Clean up calibration handle
#if USE_ESP32_VARIANT_ESP32C3 || USE_ESP32_VARIANT_ESP32C5 || USE_ESP32_VARIANT_ESP32C6 || \
@@ -287,6 +295,7 @@ float ADCSensor::sample_autorange_() {
#endif
} else {
voltage = raw * 3.3f / 4095.0f;
ESP_LOGVV(TAG, "Autorange atten=%d: NO CALIBRATION - raw=%d -> %.6fV (3.3V ref)", atten, raw, voltage);
}
return {raw, voltage};
@@ -324,18 +333,32 @@ float ADCSensor::sample_autorange_() {
}
const int adc_half = 2048;
uint32_t c12 = std::min(raw12, adc_half);
uint32_t c6 = adc_half - std::abs(raw6 - adc_half);
uint32_t c2 = adc_half - std::abs(raw2 - adc_half);
uint32_t c0 = std::min(4095 - raw0, adc_half);
uint32_t csum = c12 + c6 + c2 + c0;
const uint32_t c12 = std::min(raw12, adc_half);
const int32_t c6_signed = adc_half - std::abs(raw6 - adc_half);
const uint32_t c6 = (c6_signed > 0) ? c6_signed : 0; // Clamp to prevent underflow
const int32_t c2_signed = adc_half - std::abs(raw2 - adc_half);
const uint32_t c2 = (c2_signed > 0) ? c2_signed : 0; // Clamp to prevent underflow
const uint32_t c0 = std::min(4095 - raw0, adc_half);
const uint32_t csum = c12 + c6 + c2 + c0;
ESP_LOGVV(TAG, "Autorange summary:");
ESP_LOGVV(TAG, " Raw readings: 12db=%d, 6db=%d, 2.5db=%d, 0db=%d", raw12, raw6, raw2, raw0);
ESP_LOGVV(TAG, " Voltages: 12db=%.6f, 6db=%.6f, 2.5db=%.6f, 0db=%.6f", mv12, mv6, mv2, mv0);
ESP_LOGVV(TAG, " Coefficients: c12=%u, c6=%u, c2=%u, c0=%u, sum=%u", c12, c6, c2, c0, csum);
if (csum == 0) {
ESP_LOGE(TAG, "Invalid weight sum in autorange calculation");
return NAN;
}
return (mv12 * c12 + mv6 * c6 + mv2 * c2 + mv0 * c0) / csum;
const float final_result = (mv12 * c12 + mv6 * c6 + mv2 * c2 + mv0 * c0) / csum;
ESP_LOGV(TAG, "Autorange final: (%.6f*%u + %.6f*%u + %.6f*%u + %.6f*%u)/%u = %.6fV", mv12, c12, mv6, c6, mv2, c2, mv0,
c0, csum, final_result);
return final_result;
}
} // namespace adc