BH1750 dynamically calculate options (#3214)

* BH1750 dynamically calculate options

* Fix tests

* Fix NAN

* Convert setup to new-style

* Add myself as codeowner

CODEOWNERS

@@ -28,6 +28,7 @@ esphome/components/atc_mithermometer/* @ahpohl
 esphome/components/b_parasite/* @rbaron
 esphome/components/ballu/* @bazuchan
 esphome/components/bang_bang/* @OttoWinter
+esphome/components/bh1750/* @OttoWinter
 esphome/components/binary_sensor/* @esphome/core
 esphome/components/bl0940/* @tobias-
 esphome/components/ble_client/* @buxtronix

esphome/components/bh1750/bh1750.cpp

@@ -9,18 +9,109 @@ static const char *const TAG = "bh1750.sensor";
 static const uint8_t BH1750_COMMAND_POWER_ON = 0b00000001;
 static const uint8_t BH1750_COMMAND_MT_REG_HI = 0b01000000;  // last 3 bits
 static const uint8_t BH1750_COMMAND_MT_REG_LO = 0b01100000;  // last 5 bits
+static const uint8_t BH1750_COMMAND_ONE_TIME_L = 0b00100011;
+static const uint8_t BH1750_COMMAND_ONE_TIME_H = 0b00100000;
+static const uint8_t BH1750_COMMAND_ONE_TIME_H2 = 0b00100001;
+
+/*
+bh1750 properties:
+
+L-resolution mode:
+- resolution 4lx (@ mtreg=69)
+- measurement time: typ=16ms, max=24ms, scaled by MTreg value divided by 69
+- formula: counts / 1.2 * (69 / MTreg) lx
+H-resolution mode:
+- resolution 1lx (@ mtreg=69)
+- measurement time: typ=120ms, max=180ms, scaled by MTreg value divided by 69
+- formula: counts / 1.2 * (69 / MTreg) lx
+H-resolution mode2:
+- resolution 0.5lx (@ mtreg=69)
+- measurement time: typ=120ms, max=180ms, scaled by MTreg value divided by 69
+- formula: counts / 1.2 * (69 / MTreg) / 2 lx
+
+MTreg:
+- min=31, default=69, max=254
+
+-> only reason to use l-resolution is faster, but offers no higher range
+-> below ~7000lx, makes sense to use H-resolution2 @ MTreg=254
+-> try to maximize MTreg to get lowest noise level
+*/
 
 void BH1750Sensor::setup() {
   ESP_LOGCONFIG(TAG, "Setting up BH1750 '%s'...", this->name_.c_str());
-  if (!this->write_bytes(BH1750_COMMAND_POWER_ON, nullptr, 0)) {
+  uint8_t turn_on = BH1750_COMMAND_POWER_ON;
+  if (this->write(&turn_on, 1) != i2c::ERROR_OK) {
     this->mark_failed();
     return;
   }
+}
 
-  uint8_t mtreg_hi = (this->measurement_duration_ >> 5) & 0b111;
-  uint8_t mtreg_lo = (this->measurement_duration_ >> 0) & 0b11111;
-  this->write_bytes(BH1750_COMMAND_MT_REG_HI | mtreg_hi, nullptr, 0);
-  this->write_bytes(BH1750_COMMAND_MT_REG_LO | mtreg_lo, nullptr, 0);
+void BH1750Sensor::read_lx_(BH1750Mode mode, uint8_t mtreg, const std::function<void(float)> &f) {
+  // turn on (after one-shot sensor automatically powers down)
+  uint8_t turn_on = BH1750_COMMAND_POWER_ON;
+  if (this->write(&turn_on, 1) != i2c::ERROR_OK) {
+    ESP_LOGW(TAG, "Turning on BH1750 failed");
+    f(NAN);
+    return;
+  }
+
+  if (active_mtreg_ != mtreg) {
+    // set mtreg
+    uint8_t mtreg_hi = BH1750_COMMAND_MT_REG_HI | ((mtreg >> 5) & 0b111);
+    uint8_t mtreg_lo = BH1750_COMMAND_MT_REG_LO | ((mtreg >> 0) & 0b11111);
+    if (this->write(&mtreg_hi, 1) != i2c::ERROR_OK || this->write(&mtreg_lo, 1) != i2c::ERROR_OK) {
+      ESP_LOGW(TAG, "Setting measurement time for BH1750 failed");
+      active_mtreg_ = 0;
+      f(NAN);
+      return;
+    }
+    active_mtreg_ = mtreg;
+  }
+
+  uint8_t cmd;
+  uint16_t meas_time;
+  switch (mode) {
+    case BH1750_MODE_L:
+      cmd = BH1750_COMMAND_ONE_TIME_L;
+      meas_time = 24 * mtreg / 69;
+      break;
+    case BH1750_MODE_H:
+      cmd = BH1750_COMMAND_ONE_TIME_H;
+      meas_time = 180 * mtreg / 69;
+      break;
+    case BH1750_MODE_H2:
+      cmd = BH1750_COMMAND_ONE_TIME_H2;
+      meas_time = 180 * mtreg / 69;
+      break;
+    default:
+      f(NAN);
+      return;
+  }
+  if (this->write(&cmd, 1) != i2c::ERROR_OK) {
+    ESP_LOGW(TAG, "Starting measurement for BH1750 failed");
+    f(NAN);
+    return;
+  }
+
+  // probably not needed, but adjust for rounding
+  meas_time++;
+
+  this->set_timeout("read", meas_time, [this, mode, mtreg, f]() {
+    uint16_t raw_value;
+    if (this->read(reinterpret_cast<uint8_t *>(&raw_value), 2) != i2c::ERROR_OK) {
+      ESP_LOGW(TAG, "Reading BH1750 data failed");
+      f(NAN);
+      return;
+    }
+    raw_value = i2c::i2ctohs(raw_value);
+
+    float lx = float(raw_value) / 1.2f;
+    lx *= 69.0f / mtreg;
+    if (mode == BH1750_MODE_H2)
+      lx /= 2.0f;
+
+    f(lx);
+  });
 }
 
 void BH1750Sensor::dump_config() {
@@ -30,64 +121,49 @@ void BH1750Sensor::dump_config() {
     ESP_LOGE(TAG, "Communication with BH1750 failed!");
   }
 
-  const char *resolution_s;
-  switch (this->resolution_) {
-    case BH1750_RESOLUTION_0P5_LX:
-      resolution_s = "0.5";
-      break;
-    case BH1750_RESOLUTION_1P0_LX:
-      resolution_s = "1";
-      break;
-    case BH1750_RESOLUTION_4P0_LX:
-      resolution_s = "4";
-      break;
-    default:
-      resolution_s = "Unknown";
-      break;
-  }
-  ESP_LOGCONFIG(TAG, "  Resolution: %s", resolution_s);
   LOG_UPDATE_INTERVAL(this);
 }
 
 void BH1750Sensor::update() {
-  if (!this->write_bytes(this->resolution_, nullptr, 0))
-    return;
+  // first do a quick measurement in L-mode with full range
+  // to find right range
+  this->read_lx_(BH1750_MODE_L, 31, [this](float val) {
+    if (std::isnan(val)) {
+      this->status_set_warning();
+      this->publish_state(NAN);
+      return;
+    }
 
-  uint32_t wait = 0;
-  // use max conversion times
-  switch (this->resolution_) {
-    case BH1750_RESOLUTION_0P5_LX:
-    case BH1750_RESOLUTION_1P0_LX:
-      wait = 180;
-      break;
-    case BH1750_RESOLUTION_4P0_LX:
-      wait = 24;
-      break;
-  }
+    BH1750Mode use_mode;
+    uint8_t use_mtreg;
+    if (val <= 7000) {
+      use_mode = BH1750_MODE_H2;
+      use_mtreg = 254;
+    } else {
+      use_mode = BH1750_MODE_H;
+      // lx = counts / 1.2 * (69 / mtreg)
+      // -> mtreg = counts / 1.2 * (69 / lx)
+      // calculate for counts=50000 (allow some range to not saturate, but maximize mtreg)
+      // -> mtreg = 50000*(10/12)*(69/lx)
+      int ideal_mtreg = 50000 * 10 * 69 / (12 * (int) val);
+      use_mtreg = std::min(254, std::max(31, ideal_mtreg));
+    }
+    ESP_LOGV(TAG, "L result: %f -> Calculated mode=%d, mtreg=%d", val, (int) use_mode, use_mtreg);
 
-  this->set_timeout("illuminance", wait, [this]() { this->read_data_(); });
+    this->read_lx_(use_mode, use_mtreg, [this](float val) {
+      if (std::isnan(val)) {
+        this->status_set_warning();
+        this->publish_state(NAN);
+        return;
+      }
+      ESP_LOGD(TAG, "'%s': Got illuminance=%.1flx", this->get_name().c_str(), val);
+      this->status_clear_warning();
+      this->publish_state(val);
+    });
+  });
 }
 
 float BH1750Sensor::get_setup_priority() const { return setup_priority::DATA; }
-void BH1750Sensor::read_data_() {
-  uint16_t raw_value;
-  if (this->read(reinterpret_cast<uint8_t *>(&raw_value), 2) != i2c::ERROR_OK) {
-    this->status_set_warning();
-    return;
-  }
-  raw_value = i2c::i2ctohs(raw_value);
-
-  float lx = float(raw_value) / 1.2f;
-  lx *= 69.0f / this->measurement_duration_;
-  if (this->resolution_ == BH1750_RESOLUTION_0P5_LX) {
-    lx /= 2.0f;
-  }
-  ESP_LOGD(TAG, "'%s': Got illuminance=%.1flx", this->get_name().c_str(), lx);
-  this->publish_state(lx);
-  this->status_clear_warning();
-}
-
-void BH1750Sensor::set_resolution(BH1750Resolution resolution) { this->resolution_ = resolution; }
 
 }  // namespace bh1750
 }  // namespace esphome

esphome/components/bh1750/bh1750.h

@@ -7,29 +7,15 @@
 namespace esphome {
 namespace bh1750 {
 
-/// Enum listing all resolutions that can be used with the BH1750
-enum BH1750Resolution {
-  BH1750_RESOLUTION_4P0_LX = 0b00100011,  // one-time low resolution mode
-  BH1750_RESOLUTION_1P0_LX = 0b00100000,  // one-time high resolution mode 1
-  BH1750_RESOLUTION_0P5_LX = 0b00100001,  // one-time high resolution mode 2
+enum BH1750Mode {
+  BH1750_MODE_L,
+  BH1750_MODE_H,
+  BH1750_MODE_H2,
 };
 
 /// This class implements support for the i2c-based BH1750 ambient light sensor.
 class BH1750Sensor : public sensor::Sensor, public PollingComponent, public i2c::I2CDevice {
  public:
-  /** Set the resolution of this sensor.
-   *
-   * Possible values are:
-   *
-   *  - `BH1750_RESOLUTION_4P0_LX`
-   *  - `BH1750_RESOLUTION_1P0_LX`
-   *  - `BH1750_RESOLUTION_0P5_LX` (default)
-   *
-   * @param resolution The new resolution of the sensor.
-   */
-  void set_resolution(BH1750Resolution resolution);
-  void set_measurement_duration(uint8_t measurement_duration) { measurement_duration_ = measurement_duration; }
-
   // ========== INTERNAL METHODS ==========
   // (In most use cases you won't need these)
   void setup() override;
@@ -38,10 +24,9 @@ class BH1750Sensor : public sensor::Sensor, public PollingComponent, public i2c:
   float get_setup_priority() const override;
 
  protected:
-  void read_data_();
+  void read_lx_(BH1750Mode mode, uint8_t mtreg, const std::function<void(float)> &f);
 
-  BH1750Resolution resolution_{BH1750_RESOLUTION_0P5_LX};
-  uint8_t measurement_duration_;
+  uint8_t active_mtreg_{0};
 };
 
 }  // namespace bh1750

esphome/components/bh1750/sensor.py

@@ -2,28 +2,20 @@ import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome.components import i2c, sensor
 from esphome.const import (
-    CONF_RESOLUTION,
     DEVICE_CLASS_ILLUMINANCE,
     STATE_CLASS_MEASUREMENT,
     UNIT_LUX,
-    CONF_MEASUREMENT_DURATION,
 )
 
 DEPENDENCIES = ["i2c"]
+CODEOWNERS = ["@OttoWinter"]
 
 bh1750_ns = cg.esphome_ns.namespace("bh1750")
-BH1750Resolution = bh1750_ns.enum("BH1750Resolution")
-BH1750_RESOLUTIONS = {
-    4.0: BH1750Resolution.BH1750_RESOLUTION_4P0_LX,
-    1.0: BH1750Resolution.BH1750_RESOLUTION_1P0_LX,
-    0.5: BH1750Resolution.BH1750_RESOLUTION_0P5_LX,
-}
 
 BH1750Sensor = bh1750_ns.class_(
     "BH1750Sensor", sensor.Sensor, cg.PollingComponent, i2c.I2CDevice
 )
 
-CONF_MEASUREMENT_TIME = "measurement_time"
 CONFIG_SCHEMA = (
     sensor.sensor_schema(
         BH1750Sensor,
@@ -34,14 +26,11 @@ CONFIG_SCHEMA = (
     )
     .extend(
         {
-            cv.Optional(CONF_RESOLUTION, default=0.5): cv.enum(
-                BH1750_RESOLUTIONS, float=True
+            cv.Optional("resolution"): cv.invalid(
+                "The 'resolution' option has been removed. The optimal value is now dynamically calculated."
             ),
-            cv.Optional(CONF_MEASUREMENT_DURATION, default=69): cv.int_range(
-                min=31, max=254
-            ),
-            cv.Optional(CONF_MEASUREMENT_TIME): cv.invalid(
-                "The 'measurement_time' option has been replaced with 'measurement_duration' in 1.18.0"
+            cv.Optional("measurement_duration"): cv.invalid(
+                "The 'measurement_duration' option has been removed. The optimal value is now dynamically calculated."
             ),
         }
     )
@@ -54,6 +43,3 @@ async def to_code(config):
     var = await sensor.new_sensor(config)
     await cg.register_component(var, config)
     await i2c.register_i2c_device(var, config)
-
-    cg.add(var.set_resolution(config[CONF_RESOLUTION]))
-    cg.add(var.set_measurement_duration(config[CONF_MEASUREMENT_DURATION]))

tests/test1.yaml

@@ -456,12 +456,10 @@ sensor:
     name: "Living Room Brightness 3"
     internal: true
     address: 0x23
-    resolution: 1.0
     update_interval: 30s
     retain: False
     availability:
     state_topic: livingroom/custom_state_topic
-    measurement_duration: 31
     i2c_id: i2c_bus
   - platform: max44009
     name: "Outside Brightness 1"