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[sht4x] Fix heater causing measurement jitter (#15030)

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This commit is contained in:
J. Nick Koston
2026-03-22 10:16:46 -10:00
committed by GitHub
parent 5e68282519
commit ca0523b86c
3 changed files with 28 additions and 19 deletions
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40
esphome/components/sht4x/sht4x.cpp
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@@ -9,14 +9,12 @@ static const char *const TAG = "sht4x";
static const uint8_t MEASURECOMMANDS[] = {0xFD, 0xF6, 0xE0};
static const uint8_t SERIAL_NUMBER_COMMAND = 0x89;
void SHT4XComponent::start_heater_() {
uint8_t cmd[] = {this->heater_command_};
ESP_LOGD(TAG, "Heater turning on");
if (this->write(cmd, 1) != i2c::ERROR_OK) {
this->status_set_error(LOG_STR("Failed to turn on heater"));
}
}
// Conversion constants from SHT4x datasheet
static constexpr float TEMPERATURE_OFFSET = -45.0f;
static constexpr float TEMPERATURE_SPAN = 175.0f;
static constexpr float HUMIDITY_OFFSET = -6.0f;
static constexpr float HUMIDITY_SPAN = 125.0f;
static constexpr float RAW_MAX = 65535.0f;
void SHT4XComponent::read_serial_number_() {
uint16_t buffer[2];
@@ -39,8 +37,8 @@ void SHT4XComponent::setup() {
this->read_serial_number_();
if (std::isfinite(this->duty_cycle_) && this->duty_cycle_ > 0.0f) {
uint32_t heater_interval = static_cast<uint32_t>(static_cast<uint16_t>(this->heater_time_) / this->duty_cycle_);
ESP_LOGD(TAG, "Heater interval: %" PRIu32, heater_interval);
this->heater_interval_ = static_cast<uint32_t>(static_cast<uint16_t>(this->heater_time_) / this->duty_cycle_);
ESP_LOGD(TAG, "Heater interval: %" PRIu32, this->heater_interval_);
if (this->heater_power_ == SHT4X_HEATERPOWER_HIGH) {
if (this->heater_time_ == SHT4X_HEATERTIME_LONG) {
@@ -62,8 +60,6 @@ void SHT4XComponent::setup() {
}
}
ESP_LOGD(TAG, "Heater command: %x", this->heater_command_);
this->set_interval(heater_interval, [this]() { this->start_heater_(); });
}
}
@@ -106,19 +102,27 @@ void SHT4XComponent::update() {
// Evaluate and publish measurements
if (this->temp_sensor_ != nullptr) {
// Temp is contained in the first result word
float sensor_value_temp = buffer[0];
float temp = -45 + 175 * sensor_value_temp / 65535;
float temp = TEMPERATURE_OFFSET + TEMPERATURE_SPAN * static_cast<float>(buffer[0]) / RAW_MAX;
this->temp_sensor_->publish_state(temp);
}
if (this->humidity_sensor_ != nullptr) {
// Relative humidity is in the second result word
float sensor_value_rh = buffer[1];
float rh = -6 + 125 * sensor_value_rh / 65535;
float rh = HUMIDITY_OFFSET + HUMIDITY_SPAN * static_cast<float>(buffer[1]) / RAW_MAX;
this->humidity_sensor_->publish_state(rh);
}
// Fire heater after measurement to maximize cooldown time before the next reading.
// The heater command produces a measurement that we don't need (datasheet 4.9).
if (this->heater_interval_ > 0) {
uint32_t now = millis();
if (now - this->last_heater_millis_ >= this->heater_interval_) {
ESP_LOGD(TAG, "Heater turning on");
if (this->write_command(this->heater_command_)) {
this->last_heater_millis_ = now;
}
}
}
});
}

3
esphome/components/sht4x/sht4x.h
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@@ -35,9 +35,10 @@ class SHT4XComponent : public PollingComponent, public sensirion_common::Sensiri
SHT4XHEATERTIME heater_time_;
float duty_cycle_;
void start_heater_();
void read_serial_number_();
uint8_t heater_command_;
uint32_t heater_interval_{0};
uint32_t last_heater_millis_{0};
uint32_t serial_number_;
sensor::Sensor *temp_sensor_{nullptr};

4
tests/components/sht4x/common.yaml
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@@ -6,4 +6,8 @@ sensor:
humidity:
name: SHT4X Humidity
address: 0x44
precision: High
heater_max_duty: 0.02
heater_power: High
heater_time: Long
update_interval: 15s