Add pressure compensation during runtime (#2493)

Co-authored-by: Oxan van Leeuwen <oxan@oxanvanleeuwen.nl>

esphome/components/scd4x/scd4x.cpp

@@ -1,4 +1,5 @@
 #include "scd4x.h"
+#include "esphome/core/hal.h"
 #include "esphome/core/log.h"
 
 namespace esphome {
@@ -38,6 +39,7 @@ void SCD4XComponent::setup() {
       return;
     }
 
+    uint32_t stop_measurement_delay = 0;
     // In order to query the device periodic measurement must be ceased
     if (raw_read_status[0]) {
       ESP_LOGD(TAG, "Sensor has data available, stopping periodic measurement");
@@ -46,8 +48,11 @@ void SCD4XComponent::setup() {
         this->mark_failed();
         return;
       }
+      // According to the SCD4x datasheet the sensor will only respond to other commands after waiting 500 ms after
+      // issuing the stop_periodic_measurement command
+      stop_measurement_delay = 500;
     }
-
+    this->set_timeout(stop_measurement_delay, [this]() {
       if (!this->write_command_(SCD4X_CMD_GET_SERIAL_NUMBER)) {
         ESP_LOGE(TAG, "Failed to write get serial command");
         this->error_code_ = COMMUNICATION_FAILED;
@@ -76,7 +81,7 @@ void SCD4XComponent::setup() {
       // If pressure compensation available use it
       // else use altitude
       if (ambient_pressure_compensation_) {
-      if (!this->write_command_(SCD4X_CMD_AMBIENT_PRESSURE_COMPENSATION, ambient_pressure_compensation_)) {
+        if (!this->update_ambient_pressure_compensation_(ambient_pressure_)) {
           ESP_LOGE(TAG, "Error setting ambient pressure compensation.");
           this->error_code_ = MEASUREMENT_INIT_FAILED;
           this->mark_failed();
@@ -109,6 +114,7 @@ void SCD4XComponent::setup() {
       initialized_ = true;
       ESP_LOGD(TAG, "Sensor initialized");
     });
+  });
 }
 
 void SCD4XComponent::dump_config() {
@@ -150,6 +156,13 @@ void SCD4XComponent::update() {
     return;
   }
 
+  if (this->ambient_pressure_source_ != nullptr) {
+    float pressure = this->ambient_pressure_source_->state / 1000.0f;
+    if (!std::isnan(pressure)) {
+      set_ambient_pressure_compensation(this->ambient_pressure_source_->state / 1000.0f);
+    }
+  }
+
   // Check if data is ready
   if (!this->write_command_(SCD4X_CMD_GET_DATA_READY_STATUS)) {
     this->status_set_warning();
@@ -191,6 +204,28 @@ void SCD4XComponent::update() {
 
   this->status_clear_warning();
 }
+// Note pressure in bar here. Convert to hPa
+void SCD4XComponent::set_ambient_pressure_compensation(float pressure_in_bar) {
+  ambient_pressure_compensation_ = true;
+  uint16_t new_ambient_pressure = (uint16_t)(pressure_in_bar * 1000);
+  // remove millibar from comparison to avoid frequent updates +/- 10 millibar doesn't matter
+  if (initialized_ && (new_ambient_pressure / 10 != ambient_pressure_ / 10)) {
+    update_ambient_pressure_compensation_(new_ambient_pressure);
+    ambient_pressure_ = new_ambient_pressure;
+  } else {
+    ESP_LOGD(TAG, "ambient pressure compensation skipped - no change required");
+  }
+}
+
+bool SCD4XComponent::update_ambient_pressure_compensation_(uint16_t pressure_in_hpa) {
+  if (this->write_command_(SCD4X_CMD_AMBIENT_PRESSURE_COMPENSATION, pressure_in_hpa)) {
+    ESP_LOGD(TAG, "setting ambient pressure compensation to %d hPa", pressure_in_hpa);
+    return true;
+  } else {
+    ESP_LOGE(TAG, "Error setting ambient pressure compensation.");
+    return false;
+  }
+}
 
 uint8_t SCD4XComponent::sht_crc_(uint8_t data1, uint8_t data2) {
   uint8_t bit;

esphome/components/scd4x/scd4x.h

@@ -18,10 +18,8 @@ class SCD4XComponent : public PollingComponent, public i2c::I2CDevice {
 
   void set_automatic_self_calibration(bool asc) { enable_asc_ = asc; }
   void set_altitude_compensation(uint16_t altitude) { altitude_compensation_ = altitude; }
-  void set_ambient_pressure_compensation(float pressure) {
+  void set_ambient_pressure_compensation(float pressure_in_bar);
-    ambient_pressure_compensation_ = true;
+  void set_ambient_pressure_source(sensor::Sensor *pressure) { ambient_pressure_source_ = pressure; }
-    ambient_pressure_ = (uint16_t)(pressure * 1000);
-  }
   void set_temperature_offset(float offset) { temperature_offset_ = offset; };
 
   void set_co2_sensor(sensor::Sensor *co2) { co2_sensor_ = co2; }
@@ -33,6 +31,7 @@ class SCD4XComponent : public PollingComponent, public i2c::I2CDevice {
   bool read_data_(uint16_t *data, uint8_t len);
   bool write_command_(uint16_t command);
   bool write_command_(uint16_t command, uint16_t data);
+  bool update_ambient_pressure_compensation_(uint16_t pressure_in_hpa);
 
   ERRORCODE error_code_;
 
@@ -47,6 +46,8 @@ class SCD4XComponent : public PollingComponent, public i2c::I2CDevice {
   sensor::Sensor *co2_sensor_{nullptr};
   sensor::Sensor *temperature_sensor_{nullptr};
   sensor::Sensor *humidity_sensor_{nullptr};
+  // used for compensation
+  sensor::Sensor *ambient_pressure_source_{nullptr};
 };
 
 }  // namespace scd4x

esphome/components/scd4x/sensor.py

@@ -29,6 +29,7 @@ CONF_AUTOMATIC_SELF_CALIBRATION = "automatic_self_calibration"
 CONF_ALTITUDE_COMPENSATION = "altitude_compensation"
 CONF_AMBIENT_PRESSURE_COMPENSATION = "ambient_pressure_compensation"
 CONF_TEMPERATURE_OFFSET = "temperature_offset"
+CONF_AMBIENT_PRESSURE_COMPENSATION_SOURCE = "ambient_pressure_compensation_source"
 
 CONFIG_SCHEMA = (
     cv.Schema(
@@ -62,6 +63,9 @@ CONFIG_SCHEMA = (
             ),
             cv.Optional(CONF_AMBIENT_PRESSURE_COMPENSATION): cv.pressure,
             cv.Optional(CONF_TEMPERATURE_OFFSET, default="4°C"): cv.temperature,
+            cv.Optional(CONF_AMBIENT_PRESSURE_COMPENSATION_SOURCE): cv.use_id(
+                sensor.Sensor
+            ),
         }
     )
     .extend(cv.polling_component_schema("60s"))
@@ -92,7 +96,10 @@ async def to_code(config):
             cg.add(getattr(var, funcName)(config[key]))
 
     for key, funcName in SENSOR_MAP.items():
-
         if key in config:
             sens = await sensor.new_sensor(config[key])
             cg.add(getattr(var, funcName)(sens))
+
+    if CONF_AMBIENT_PRESSURE_COMPENSATION_SOURCE in config:
+        sens = await cg.get_variable(config[CONF_AMBIENT_PRESSURE_COMPENSATION_SOURCE])
+        cg.add(var.set_ambient_pressure_source(sens))