MH-Z19 calibration support (#683)

* Allow configuration to enable or disable automatic baseline calibration on boot
* Add actions to enable or disable automatic baseline calibration
* Add action to calibrate zero point

esphome/components/mhz19/mhz19.cpp

@@ -8,6 +8,9 @@ static const char *TAG = "mhz19";
 static const uint8_t MHZ19_REQUEST_LENGTH = 8;
 static const uint8_t MHZ19_RESPONSE_LENGTH = 9;
 static const uint8_t MHZ19_COMMAND_GET_PPM[] = {0xFF, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00};
+static const uint8_t MHZ19_COMMAND_ABC_ENABLE[] = {0xFF, 0x01, 0x79, 0xA0, 0x00, 0x00, 0x00, 0x00};
+static const uint8_t MHZ19_COMMAND_ABC_DISABLE[] = {0xFF, 0x01, 0x79, 0x00, 0x00, 0x00, 0x00, 0x00};
+static const uint8_t MHZ19_COMMAND_CALIBRATE_ZERO[] = {0xFF, 0x01, 0x87, 0x00, 0x00, 0x00, 0x00, 0x00};
 
 uint8_t mhz19_checksum(const uint8_t *command) {
   uint8_t sum = 0;
@@ -17,6 +20,14 @@ uint8_t mhz19_checksum(const uint8_t *command) {
   return 0xFF - sum + 0x01;
 }
 
+void MHZ19Component::setup() {
+  if (this->abc_boot_logic_ == MHZ19_ABC_ENABLED) {
+    this->abc_enable();
+  } else if (this->abc_boot_logic_ == MHZ19_ABC_DISABLED) {
+    this->abc_disable();
+  }
+}
+
 void MHZ19Component::update() {
   uint8_t response[MHZ19_RESPONSE_LENGTH];
   if (!this->mhz19_write_command_(MHZ19_COMMAND_GET_PPM, response)) {
@@ -50,6 +61,21 @@ void MHZ19Component::update() {
     this->temperature_sensor_->publish_state(temp);
 }
 
+void MHZ19Component::calibrate_zero() {
+  ESP_LOGD(TAG, "MHZ19 Calibrating zero point");
+  this->mhz19_write_command_(MHZ19_COMMAND_CALIBRATE_ZERO, nullptr);
+}
+
+void MHZ19Component::abc_enable() {
+  ESP_LOGD(TAG, "MHZ19 Enabling automatic baseline calibration");
+  this->mhz19_write_command_(MHZ19_COMMAND_ABC_ENABLE, nullptr);
+}
+
+void MHZ19Component::abc_disable() {
+  ESP_LOGD(TAG, "MHZ19 Disabling automatic baseline calibration");
+  this->mhz19_write_command_(MHZ19_COMMAND_ABC_DISABLE, nullptr);
+}
+
 bool MHZ19Component::mhz19_write_command_(const uint8_t *command, uint8_t *response) {
   this->flush();
   this->write_array(command, MHZ19_REQUEST_LENGTH);
@@ -67,6 +93,12 @@ void MHZ19Component::dump_config() {
   ESP_LOGCONFIG(TAG, "MH-Z19:");
   LOG_SENSOR("  ", "CO2", this->co2_sensor_);
   LOG_SENSOR("  ", "Temperature", this->temperature_sensor_);
+
+  if (this->abc_boot_logic_ == MHZ19_ABC_ENABLED) {
+    ESP_LOGCONFIG(TAG, "  Automatic baseline calibration enabled on boot");
+  } else if (this->abc_boot_logic_ == MHZ19_ABC_DISABLED) {
+    ESP_LOGCONFIG(TAG, "  Automatic baseline calibration disabled on boot");
+  }
 }
 
 }  // namespace mhz19

esphome/components/mhz19/mhz19.h

@@ -1,27 +1,64 @@
 #pragma once
 
 #include "esphome/core/component.h"
+#include "esphome/core/automation.h"
 #include "esphome/components/sensor/sensor.h"
 #include "esphome/components/uart/uart.h"
 
 namespace esphome {
 namespace mhz19 {
 
+enum MHZ19ABCLogic { MHZ19_ABC_NONE = 0, MHZ19_ABC_ENABLED, MHZ19_ABC_DISABLED };
+
 class MHZ19Component : public PollingComponent, public uart::UARTDevice {
  public:
   float get_setup_priority() const override;
 
+  void setup() override;
   void update() override;
   void dump_config() override;
 
+  void calibrate_zero();
+  void abc_enable();
+  void abc_disable();
+
   void set_temperature_sensor(sensor::Sensor *temperature_sensor) { temperature_sensor_ = temperature_sensor; }
   void set_co2_sensor(sensor::Sensor *co2_sensor) { co2_sensor_ = co2_sensor; }
+  void set_abc_enabled(bool abc_enabled) { abc_boot_logic_ = abc_enabled ? MHZ19_ABC_ENABLED : MHZ19_ABC_DISABLED; }
 
  protected:
   bool mhz19_write_command_(const uint8_t *command, uint8_t *response);
 
   sensor::Sensor *temperature_sensor_{nullptr};
   sensor::Sensor *co2_sensor_{nullptr};
+  MHZ19ABCLogic abc_boot_logic_{MHZ19_ABC_NONE};
+};
+
+template<typename... Ts> class MHZ19CalibrateZeroAction : public Action<Ts...> {
+ public:
+  MHZ19CalibrateZeroAction(MHZ19Component *mhz19) : mhz19_(mhz19) {}
+  void play(Ts... x) override { this->mhz19_->calibrate_zero(); }
+
+ protected:
+  MHZ19Component *mhz19_;
+};
+
+template<typename... Ts> class MHZ19ABCEnableAction : public Action<Ts...> {
+ public:
+  MHZ19ABCEnableAction(MHZ19Component *mhz19) : mhz19_(mhz19) {}
+  void play(Ts... x) override { this->mhz19_->abc_enable(); }
+
+ protected:
+  MHZ19Component *mhz19_;
+};
+
+template<typename... Ts> class MHZ19ABCDisableAction : public Action<Ts...> {
+ public:
+  MHZ19ABCDisableAction(MHZ19Component *mhz19) : mhz19_(mhz19) {}
+  void play(Ts... x) override { this->mhz19_->abc_disable(); }
+
+ protected:
+  MHZ19Component *mhz19_;
 };
 
 }  // namespace mhz19

esphome/components/mhz19/sensor.py

@@ -1,18 +1,26 @@
 import esphome.codegen as cg
 import esphome.config_validation as cv
+from esphome import automation
+from esphome.automation import maybe_simple_id
 from esphome.components import sensor, uart
 from esphome.const import CONF_CO2, CONF_ID, CONF_TEMPERATURE, ICON_PERIODIC_TABLE_CO2, \
     UNIT_PARTS_PER_MILLION, UNIT_CELSIUS, ICON_THERMOMETER
 
 DEPENDENCIES = ['uart']
 
+CONF_AUTOMATIC_BASELINE_CALIBRATION = 'automatic_baseline_calibration'
+
 mhz19_ns = cg.esphome_ns.namespace('mhz19')
 MHZ19Component = mhz19_ns.class_('MHZ19Component', cg.PollingComponent, uart.UARTDevice)
+MHZ19CalibrateZeroAction = mhz19_ns.class_('MHZ19CalibrateZeroAction', automation.Action)
+MHZ19ABCEnableAction = mhz19_ns.class_('MHZ19ABCEnableAction', automation.Action)
+MHZ19ABCDisableAction = mhz19_ns.class_('MHZ19ABCDisableAction', automation.Action)
 
 CONFIG_SCHEMA = cv.Schema({
     cv.GenerateID(): cv.declare_id(MHZ19Component),
     cv.Required(CONF_CO2): sensor.sensor_schema(UNIT_PARTS_PER_MILLION, ICON_PERIODIC_TABLE_CO2, 0),
     cv.Optional(CONF_TEMPERATURE): sensor.sensor_schema(UNIT_CELSIUS, ICON_THERMOMETER, 0),
+    cv.Optional(CONF_AUTOMATIC_BASELINE_CALIBRATION): cv.boolean,
 }).extend(cv.polling_component_schema('60s')).extend(uart.UART_DEVICE_SCHEMA)
 
 
@@ -28,3 +36,22 @@ def to_code(config):
     if CONF_TEMPERATURE in config:
         sens = yield sensor.new_sensor(config[CONF_TEMPERATURE])
         cg.add(var.set_temperature_sensor(sens))
+
+    if CONF_AUTOMATIC_BASELINE_CALIBRATION in config:
+        cg.add(var.set_abc_enabled(config[CONF_AUTOMATIC_BASELINE_CALIBRATION]))
+
+
+CALIBRATION_ACTION_SCHEMA = maybe_simple_id({
+    cv.Required(CONF_ID): cv.use_id(MHZ19Component),
+})
+
+
+@automation.register_action('mhz19.calibrate_zero', MHZ19CalibrateZeroAction,
+                            CALIBRATION_ACTION_SCHEMA)
+@automation.register_action('mhz19.abc_enable', MHZ19ABCEnableAction,
+                            CALIBRATION_ACTION_SCHEMA)
+@automation.register_action('mhz19.abc_disable', MHZ19ABCDisableAction,
+                            CALIBRATION_ACTION_SCHEMA)
+def mhz19_calibration_to_code(config, action_id, template_arg, args):
+    paren = yield cg.get_variable(config[CONF_ID])
+    yield cg.new_Pvariable(action_id, template_arg, paren)

tests/test1.yaml

@@ -449,6 +449,7 @@ sensor:
     temperature:
       name: "MH-Z19 Temperature"
     update_interval: 15s
+    automatic_baseline_calibration: false
   - platform: mpu6050
     address: 0x68
     accel_x: