Document Core2 BLE proxy power and UI logic

esphome/lab-ble-proxy.h

@@ -25,12 +25,16 @@ namespace owon_b35t {
 using esphome::Color;
 using esphome::display::Display;
 
+// Log tags used by ESPHome for BLE meter parsing and Core2 power-management messages.
 static const char *const TAG = "owon_b35t";
 static const char *const POWER_TAG = "core2_power";
+
+// The M5Stack Core2 routes LCD/backlight power through an AXP192 PMIC on I2C.
 static constexpr uint8_t AXP192_ADDR = 0x34;
 static esphome::i2c::I2CDevice axp192;
-static bool axp192_ready = false;
+static bool axp192_ready = false;  // Guard PMIC accesses until the I2C bus/address has been configured.
 
+// Write one byte to an AXP192 register and log failures instead of silently losing power changes.
 static bool axp_write(uint8_t reg, uint8_t value) {
   if (!axp192_ready) return false;
   bool ok = axp192.write_byte(reg, value);
@@ -38,6 +42,7 @@ static bool axp_write(uint8_t reg, uint8_t value) {
   return ok;
 }
 
+// Read one byte from an AXP192 register; callers use this before read/modify/write updates.
 static bool axp_read(uint8_t reg, uint8_t *value) {
   if (!axp192_ready) return false;
   bool ok = axp192.read_byte(reg, value);
@@ -45,6 +50,7 @@ static bool axp_read(uint8_t reg, uint8_t *value) {
   return ok;
 }
 
+// Clear and set selected bits in an AXP192 register while preserving all other bits.
 static void axp_update(uint8_t reg, uint8_t clear_mask, uint8_t set_mask) {
   uint8_t value = 0;
   if (!axp_read(reg, &value)) return;
@@ -52,24 +58,28 @@ static void axp_update(uint8_t reg, uint8_t clear_mask, uint8_t set_mask) {
   axp_write(reg, value);
 }
 
+// Convert a desired DCDC output voltage to the 25 mV-step register encoding used by AXP192.
 static uint8_t axp_dc_voltage_data(uint16_t millivolts) {
   if (millivolts < 700) millivolts = 700;
   if (millivolts > 3500) millivolts = 3500;
   return static_cast<uint8_t>((millivolts - 700) / 25) & 0x7F;
 }
 
+// Convert a desired LDO voltage to the 100 mV-step register encoding used by AXP192.
 static uint8_t axp_ldo_voltage_data(uint16_t millivolts) {
   if (millivolts < 1800) millivolts = 1800;
   if (millivolts > 3300) millivolts = 3300;
   return static_cast<uint8_t>((millivolts - 1800) / 100) & 0x0F;
 }
 
+// Set the LCD backlight rail (DCDC3) voltage; brightness is controlled by this rail voltage.
 static void core2_axp192_set_lcd_voltage(uint16_t millivolts) {
   uint8_t value = 0;
   axp_read(0x27, &value);
   axp_write(0x27, (value & 0x80) | axp_dc_voltage_data(millivolts));  // DCDC3, LCD backlight
 }
 
+// Map a 0.0-1.0 brightness value to the Core2 LCD backlight voltage and enable/disable DCDC3.
 static void core2_axp192_set_backlight(float brightness) {
   if (brightness <= 0.0f) {
     axp_update(0x12, 0x02, 0x00);  // DCDC3 off
@@ -81,6 +91,7 @@ static void core2_axp192_set_backlight(float brightness) {
   axp_update(0x12, 0x00, 0x02);  // DCDC3 on
 }
 
+// Initialize the Core2 PMIC rails needed by ESP32, LCD logic, LCD backlight, and the display reset line.
 static void core2_axp192_init(esphome::i2c::I2CBus *bus) {
   axp192.set_i2c_bus(bus);
   axp192.set_i2c_address(AXP192_ADDR);
@@ -113,6 +124,7 @@ static void core2_axp192_init(esphome::i2c::I2CBus *bus) {
   core2_axp192_set_backlight(1.0f);
 }
 
+// 16x16 monochrome status icons drawn manually into the ESPHome display framebuffer.
 static const uint8_t ACCU_BMP[32] = {
     0b00000000, 0b00000000,
     0b00000000, 0b00000000,
@@ -229,6 +241,8 @@ static const uint8_t BUZZ_BMP[32] = {
 
 class Meter {
  public:
+  // Offsets and bit masks for the 14-byte "classic" OWON frame layout. B35T+ frames are
+  // normalized into this same buffer so the rest of the code can use one representation.
   static constexpr uint8_t REGPLUSMINUS = 0x00;
   static constexpr uint8_t FLAGPLUS = 0b00101011;
   static constexpr uint8_t FLAGMINUS = 0b00101101;
@@ -268,24 +282,29 @@ class Meter {
   static constexpr uint8_t FLAGUNITAMP = 0b01000000;
   static constexpr uint8_t FLAGUNITVOLT = 0b10000000;
 
-  bool connected{false};
+  // Connection and decoded meter state consumed by ESPHome sensors and the local display.
-  bool write_available{false};
+  bool connected{false};       // BLE link to the OWON meter is currently established.
-  bool is_plus{false};
+  bool write_available{false}; // The writable BLE characteristic is ready for button commands.
-  bool low_battery{false};
+  bool is_plus{false};         // True when the last notification used the compact B35T+ frame format.
-  bool overload{false};
+  bool low_battery{false};     // Battery indicator decoded from the meter status bits.
-  bool has_reading{false};
+  bool overload{false};        // True when the meter reports OL instead of numeric digits.
-  uint8_t selected_button{1};
+  bool has_reading{false};     // At least one valid BLE notification has been decoded.
-  uint32_t last_notify_ms{0};
+  uint8_t selected_button{1};  // UI-selected OWON remote button command (1..6).
+  uint32_t last_notify_ms{0};  // Timestamp of the last accepted meter notification.
 
+  // Decode a BLE notification from either supported OWON protocol variant and refresh cached values.
   bool handle_notify(const std::vector<uint8_t> &data) {
     if (data.size() > sizeof(this->raw_))
       return false;
+
+    // B35T+ sends a compact 6-byte binary frame; convert it into the classic 14-byte layout.
     if (data.size() == 6 && data[1] >= 0xF0) {
       memset(this->raw_, 0, sizeof(this->raw_));
       memcpy(this->raw_, data.data(), data.size());
       this->is_plus = true;
       this->parse_plus_();
     } else if (data.size() == 14 && data[12] == 0x0D && data[13] == 0x0A) {
+      // Classic B35T sends an ASCII-like 14-byte frame terminated by CR/LF; it can be used directly.
       memset(this->value_, 0, sizeof(this->value_));
       memcpy(this->value_, data.data(), data.size());
       this->is_plus = false;
@@ -294,26 +313,32 @@ class Meter {
       return false;
     }
 
+    // Cache derived states so display drawing and Home Assistant sensors do not have to re-parse frames.
     this->overload = memcmp(this->value_, OVERLOAD_FRAME, sizeof(OVERLOAD_FRAME)) == 0;
-    this->display_value = this->calc_display_value_();
+    this->display_value = this->calc_display_value_();     // Numeric value exactly as shown on the meter.
-    this->base_value = this->calc_base_value_();
+    this->base_value = this->calc_base_value_();           // Same reading converted to base SI scale.
     this->has_reading = true;
     this->last_notify_ms = millis();
     return true;
   }
 
+  // Called by the ESPHome BLE client once the meter connection and write characteristic are usable.
   void on_connect() {
     this->connected = true;
     this->write_available = true;
   }
 
+  // Reset connection flags when BLE disconnects; the last reading is kept for display/sensor continuity.
   void on_disconnect() {
     this->connected = false;
     this->write_available = false;
   }
 
+  // Numeric accessors used by ESPHome lambdas when publishing sensor state to Home Assistant.
   float value() const { return this->display_value; }
   float value_base() const { return this->base_value; }
+
+  // Boolean flag helpers keep the bit-mask details out of UI and sensor publishing code.
   bool negative() const { return (this->value_[REGPLUSMINUS] & FLAGMINUS) == FLAGMINUS; }
   bool auto_range() const { return (this->value_[REGMODE] & FLAGMODEAUTO) == FLAGMODEAUTO; }
   bool hold() const { return (this->value_[REGMODE] & FLAGMODEHOLD) == FLAGMODEHOLD; }
@@ -325,6 +350,7 @@ class Meter {
   bool diode() const { return (this->value_[REGSCALE] & FLAGSCALEDIODE) == FLAGSCALEDIODE; }
   bool continuity() const { return (this->value_[REGSCALE] & FLAGSCALEBUZZ) == FLAGSCALEBUZZ; }
 
+  // Translate decoded unit bits into the text suffix shown on the display and exposed via sensors.
   const char *unit() const {
     switch (this->value_[REGUNIT]) {
       case FLAGUNITFAHR: return "°F";
@@ -339,6 +365,7 @@ class Meter {
     }
   }
 
+  // Translate decoded scale bits into SI prefixes or duty-cycle percent.
   const char *scale() const {
     if ((this->value_[REGSCALE] & FLAGSCALEDUTY) == FLAGSCALEDUTY) return "%";
     if ((this->value_[REGSCALE] & FLAGSCALEMEGA) == FLAGSCALEMEGA) return "M";
@@ -348,6 +375,7 @@ class Meter {
     return "";
   }
 
+  // Build a compact human-readable list of active meter modes for Home Assistant text sensors.
   std::string mode_text() const {
     std::string out;
     if (this->dc()) out += "DC ";
@@ -363,6 +391,7 @@ class Meter {
     return out;
   }
 
+  // Format the current reading as a single string, including disconnected/waiting/overload states.
   std::string reading_text() const {
     if (!this->connected) return "Disconnected";
     if (!this->has_reading) return "Waiting for data";
@@ -372,6 +401,7 @@ class Meter {
     return std::string(buf);
   }
 
+  // Classify the reading so ESPHome can publish it to the correct measurement-specific sensor.
   enum Kind { KIND_OTHER, KIND_VOLTAGE, KIND_CURRENT, KIND_RESISTANCE, KIND_FREQUENCY, KIND_CAPACITANCE, KIND_TEMP_C, KIND_TEMP_F, KIND_DUTY };
   Kind kind() const {
     if ((this->value_[REGSCALE] & FLAGSCALEDUTY) == FLAGSCALEDUTY) return KIND_DUTY;
@@ -387,6 +417,7 @@ class Meter {
     }
   }
 
+  // UI label for the currently selected remote-control command sent back to the OWON meter.
   const char *selected_button_name() const {
     static const char *const names[] = {"SELECT", "RANGE", "HLD/LIG", "REL/BT", "HZ/DUTY", "MAX/MIN"};
     uint8_t index = this->selected_button;
@@ -395,6 +426,7 @@ class Meter {
     return names[index - 1];
   }
 
+  // Move the selected remote button left/right; bounds match the six commands in selected_button_name().
   void previous_button() {
     if (this->selected_button > 1) this->selected_button--;
   }
@@ -402,6 +434,7 @@ class Meter {
     if (this->selected_button < 6) this->selected_button++;
   }
 
+  // Draw either the OWON multimeter page or the Atorch DL24 load page on the M5Stack display.
   void render(esphome::display::Display &it, esphome::display::BaseFont *font,
               esphome::display::BaseFont *value_font, int display_page = 0,
               bool atorch_connected = false,
@@ -422,7 +455,9 @@ class Meter {
     if (display_page == 0) {
         // --- PAGE 1: OWON Multimeter ---
         it.fill(bg);
-        bool status_active = this->connected && this->has_reading;
+        bool status_active = this->connected && this->has_reading;  // Only highlight decoded flags after data arrives.
+
+        // Top status row mirrors the physical meter annunciators: battery, BLE, range, min/max, hold, rel, diode, buzzer.
         this->draw_icon_(it, 12, 8, 16, 16, ACCU_BMP, status_active ? (this->low_battery ? red : green) : inactive);
         this->draw_icon_(it, 46, 8, 16, 16, BLE_BMP, this->connected ? blue : inactive);
         this->label_(it, font, 86, 8, "AUTO", status_active && this->auto_range() ? fg : inactive);
@@ -436,6 +471,7 @@ class Meter {
         this->label_(it, font, 8, 104, "DC", status_active && this->dc() ? cyan : inactive);
         this->label_(it, font, 8, 124, "AC", status_active && this->ac() ? magenta : inactive);
 
+        // Main seven-segment area distinguishes connection, waiting-for-first-frame, overload, and normal readings.
         if (!this->connected) {
         this->draw_digits_(it, "----", false, inactive);
         it.print(160, 148, font, inactive, esphome::display::TextAlign::CENTER, "scan/connect");
@@ -462,6 +498,8 @@ class Meter {
 
         bool bargraph_active = status_active && !this->overload;
         this->draw_bargraph_(it, bargraph_active ? this->digits_from_buffer_() : 0, bargraph_active);
+
+        // Bottom soft-button row shows the currently selected OWON command and whether BLE writes are available.
         it.filled_rectangle(34, 212, 40, 24, this->write_available ? fg : inactive);
         it.filled_rectangle(108, 212, 100, 24, this->write_available ? fg : inactive);
         it.filled_rectangle(242, 212, 40, 24, this->write_available ? fg : inactive);
@@ -488,6 +526,7 @@ class Meter {
         const Color temp_color = atorch_connected ? magenta : dim_accent;
         const Color header_color = atorch_connected ? cyan : dim_value;
 
+        // Prepare formatted metric strings before drawing so missing/NaN Atorch values display consistently.
         char voltage_text[24];
         char current_text[24];
         char power_text[24];
@@ -508,6 +547,7 @@ class Meter {
         }
         it.print(310, 7, font, inactive, esphome::display::TextAlign::TOP_RIGHT, "DC LOAD");
 
+        // Four primary Atorch measurements are shown as dashboard cards; accumulated counters fit in the footer.
         this->draw_metric_card_(it, font, value_font, 10, 42, 145, 76, "VOLTAGE", voltage_text, voltage_color, panel, border, value_color);
         this->draw_metric_card_(it, font, value_font, 165, 42, 145, 76, "CURRENT", current_text, current_color, panel, border, value_color);
         this->draw_metric_card_(it, font, value_font, 10, 128, 145, 76, "POWER", power_text, power_color, panel, border, value_color);
@@ -526,12 +566,13 @@ class Meter {
   }
 
  private:
-  uint8_t raw_[14]{};
+  uint8_t raw_[14]{};    // Last raw BLE payload, padded to the maximum supported OWON frame length.
-  uint8_t value_[14]{};
+  uint8_t value_[14]{};  // Normalized classic-frame view used by all accessors and display rendering.
-  float display_value{NAN};
+  float display_value{NAN};  // Meter reading with its displayed prefix still applied, e.g. 12.3 kΩ -> 12.3.
-  float base_value{NAN};
+  float base_value{NAN};     // Meter reading converted to base units, e.g. 12.3 kΩ -> 12300 Ω.
-  static constexpr uint8_t OVERLOAD_FRAME[5] = {0x2B, 0x3F, 0x30, 0x3A, 0x3F};
+  static constexpr uint8_t OVERLOAD_FRAME[5] = {0x2B, 0x3F, 0x30, 0x3A, 0x3F};  // "+?0:?" OL marker.
 
+  // Reconstruct the four visible seven-segment digits as an integer for value calculations/bargraph scaling.
   uint16_t digits_from_buffer_() const {
     uint16_t out = 0;
     if (this->value_[REGDIG1] >= '0' && this->value_[REGDIG1] <= '9') out += (this->value_[REGDIG1] - '0') * 1000;
@@ -541,10 +582,12 @@ class Meter {
     return out;
   }
 
+  // Convert the normalized frame into the floating-point number shown by the meter display.
   float calc_display_value_() const {
     if (this->overload) return NAN;
 
     if (this->is_plus) {
+      // B35T+ encodes decimal placement and sign/magnitude as packed little-endian words.
       uint16_t pair1 = static_cast<uint16_t>(this->raw_[0]) | (static_cast<uint16_t>(this->raw_[1]) << 8);
       uint8_t decimal = pair1 & 0x07;
       if (decimal >= 7) return NAN;
@@ -556,6 +599,7 @@ class Meter {
       return negative ? -v : v;
     }
 
+    // Classic frames carry decimal placement as one of three point flags in the normalized buffer.
     uint8_t decimal = 0;
     switch (this->value_[REGPOINT] & 0x07) {
       case 0b001: decimal = 1; break;
@@ -567,6 +611,7 @@ class Meter {
     return this->negative() ? -v : v;
   }
 
+  // Apply the decoded SI prefix so Home Assistant receives comparable base-unit sensor values.
   float calc_base_value_() const {
     if (std::isnan(this->display_value)) return NAN;
     if (this->value_[REGUNIT] == FLAGUNITNF) return this->display_value * 1e-9f;
@@ -577,17 +622,20 @@ class Meter {
     return this->display_value;
   }
 
+  // Decode the compact B35T+ payload and synthesize the 14-byte classic representation.
   void parse_plus_() {
     memset(this->value_, 0, sizeof(this->value_));
     this->value_[5] = 0x20;
     this->value_[12] = 0x0D;
     this->value_[13] = 0x0A;
 
+    // First word: measurement function, SI scale, and decimal-point position.
     uint16_t pair1 = static_cast<uint16_t>(this->raw_[0]) | (static_cast<uint16_t>(this->raw_[1]) << 8);
     uint8_t function = (pair1 >> 6) & 0x0F;
     uint8_t scale = (pair1 >> 3) & 0x07;
     uint8_t decimal = pair1 & 0x07;
 
+    // Translate B35T+ decimal count to the classic point-flag convention used by draw_decimal_points_().
     switch (decimal) {
       case 0: this->value_[REGPOINT] = FLAGPOINT0; break;
       case 1: this->value_[REGPOINT] = FLAGPOINT3; break;
@@ -596,6 +644,7 @@ class Meter {
       default: break;
     }
 
+    // Translate the function selector into classic unit and AC/DC/mode flags.
     switch (function) {
       case 0: this->value_[REGUNIT] |= FLAGUNITVOLT; this->value_[REGMODE] |= FLAGMODEDC; break;
       case 1: this->value_[REGUNIT] |= FLAGUNITVOLT; this->value_[REGMODE] |= FLAGMODEAC; break;
@@ -613,6 +662,7 @@ class Meter {
       default: break;
     }
 
+    // Translate the B35T+ scale selector into SI-prefix flags.
     switch (scale) {
       case 2: this->value_[REGSCALE] |= FLAGSCALEMICRO; break;
       case 3: this->value_[REGSCALE] |= FLAGSCALEMILLI; break;
@@ -621,6 +671,7 @@ class Meter {
       default: break;
     }
 
+    // Second word: status flags such as hold, relative, auto-range, battery, and min/max.
     uint16_t pair2 = static_cast<uint16_t>(this->raw_[2]) | (static_cast<uint16_t>(this->raw_[3]) << 8);
     if (pair2 & (1 << 0)) this->value_[REGMODE] |= FLAGMODEHOLD;
     if (pair2 & (1 << 1)) this->value_[REGMODE] |= FLAGMODEREL;
@@ -629,6 +680,7 @@ class Meter {
     if (pair2 & (1 << 4)) this->value_[REGMINMAX] |= FLAGMIN;
     if (pair2 & (1 << 5)) this->value_[REGMINMAX] |= FLAGMAX;
 
+    // Third word: signed 4-digit display value, with bit 15 indicating a negative reading.
     uint16_t pair3 = static_cast<uint16_t>(this->raw_[4]) | (static_cast<uint16_t>(this->raw_[5]) << 8);
     if (decimal < 7) {
       uint16_t digits = pair3;
@@ -643,15 +695,18 @@ class Meter {
       this->value_[REGDIG3] = '0' + ((digits / 10) % 10);
       this->value_[REGDIG4] = '0' + (digits % 10);
     } else {
+      // Decimal values 7 and above are used by this protocol to indicate overload/OL.
       memcpy(this->value_, OVERLOAD_FRAME, sizeof(OVERLOAD_FRAME));
     }
   }
 
+  // Return a printable digit for a display register, using a blank for non-digit status bytes.
   char digit_char_(uint8_t reg) const {
     uint8_t c = this->value_[reg];
     return (c >= '0' && c <= '9') ? static_cast<char>(c) : ' ';
   }
 
+  // Format Atorch metrics, using "--" for missing values while keeping units visible.
   void format_metric_(char *buffer, size_t size, float value, const char *unit, uint8_t decimals) const {
     if (!std::isfinite(value)) {
       snprintf(buffer, size, "-- %s", unit);
@@ -662,6 +717,7 @@ class Meter {
     snprintf(buffer, size, format, value, unit);
   }
 
+  // Draw one Atorch dashboard tile with a colored accent, label, and centered numeric value.
   void draw_metric_card_(Display &it, esphome::display::BaseFont *label_font, esphome::display::BaseFont *value_font,
                          int x, int y, int w, int h, const char *title, const char *value,
                          Color accent, Color fill, Color border, Color value_color) {
@@ -678,10 +734,12 @@ class Meter {
     it.filled_rectangle(x + 10, y + h - 11, w - 20, 1, accent);
   }
 
+  // Small wrapper for consistent top-left aligned labels.
   void label_(Display &it, esphome::display::BaseFont *font, int x, int y, const char *text, Color color) {
     it.print(x, y, font, color, esphome::display::TextAlign::TOP_LEFT, text);
   }
 
+  // Draw the large four-digit OWON readout, including a separate minus sign when needed.
   void draw_digits_(Display &it, const char *text, bool negative, Color color) {
     if (negative) this->draw_segment_(it, 8, 83, 26, 9, true, color);
     constexpr int digit_x = 40;
@@ -694,6 +752,7 @@ class Meter {
     }
   }
 
+  // Draw decimal points between the large seven-segment digits according to the normalized frame flags.
   void draw_decimal_points_(Display &it, Color color) {
     uint8_t p = this->value_[REGPOINT];
     if ((p & FLAGPOINT1) == FLAGPOINT1) it.filled_rectangle(95, 135, 8, 10, color);
@@ -701,6 +760,7 @@ class Meter {
     if ((p & FLAGPOINT3) == FLAGPOINT3) it.filled_rectangle(223, 135, 8, 10, color);
   }
 
+  // Draw one beveled horizontal or vertical segment used by the custom seven-segment font.
   void draw_segment_(Display &it, int x, int y, int w, int h, bool horizontal, Color color) {
     if (horizontal) {
       int cap = h / 2;
@@ -715,6 +775,7 @@ class Meter {
     }
   }
 
+  // Plot a packed 1-bit bitmap icon, where each set bit becomes one colored display pixel.
   void draw_icon_(Display &it, int x, int y, int w, int h, const uint8_t *data, Color color) {
     for (int row = 0; row < h; row++) {
       for (int col = 0; col < w; col++) {
@@ -726,6 +787,7 @@ class Meter {
     }
   }
 
+  // Map a digit/OL/minus character to seven segment states and draw the active segments.
   void draw_seven_segment_(Display &it, int x, int y, int w, int h, char ch, Color color) {
     bool a=false,b=false,c=false,d=false,e=false,f=false,g=false;
     switch (ch) {
@@ -766,6 +828,7 @@ class Meter {
     if (g) this->draw_segment_(it, x + t / 2, mid_y, w - t, t, true, color);
   }
 
+  // Draw the OWON-style bottom bargraph by scaling raw 0..6000 display digits to a 240 px ruler.
   void draw_bargraph_(Display &it, uint16_t digits, bool active) {
     const Color fg(255, 255, 255);
     const Color inactive(80, 80, 80);

esphome/lab-ble-proxy.yaml

@@ -29,6 +29,9 @@ esphome:
   on_boot:
     priority: 850
     then:
+      # The Core2 LCD/backlight rails are controlled by the AXP192 PMIC. ESPHome's
+      # stock M5CORE2 display setup does not initialize those rails here, so the
+      # custom header performs the M5Stack-specific power sequencing once I2C exists.
       - lambda: |-
           owon_b35t::core2_axp192_init(id(core2_i2c));
   project:
@@ -77,10 +80,14 @@ wifi:
 captive_portal:
 
 globals:
+  # 0 = OWON meter page, 1 = Atorch DL24 page. This is intentionally volatile so
+  # every boot starts with the multimeter view until one device connects.
   - id: display_page
     type: int
     initial_value: "0"
     restore_value: no
+  # The Atorch external component does not expose a simple connected flag that the
+  # display lambda can query, so BLE callbacks maintain this state explicitly.
   - id: atorch_connected
     type: bool
     initial_value: "false"
@@ -100,15 +107,19 @@ script:
       - delay: 2min
       - if:
           condition:
+            # Only dim when both BLE devices are disconnected; active lab instruments
+            # keep the display fully lit so readings remain visible at a glance.
             lambda: |-
               return !owon_meter.connected && !id(atorch_connected);
           then:
             - light.turn_on:
                 id: backlight
-                brightness: 50%
+                brightness: 70%
       - delay: 3min
       - if:
           condition:
+            # Re-check before turning the backlight off, because a connection may
+            # have been established during the preceding delay.
             lambda: |-
               return !owon_meter.connected && !id(atorch_connected);
           then:
@@ -117,6 +128,8 @@ script:
 interval:
   - interval: 10s
     then:
+      # Periodic memory telemetry is useful on the Core2 because BLE, PSRAM, the
+      # MIPI framebuffer, and external components can fragment different heap pools.
       - lambda: |-
           ESP_LOGI("mem", "heap free=%u min_free=%u internal_free=%u internal_largest=%u dma_free=%u dma_largest=%u psram_free=%u psram_largest=%u",
                    static_cast<unsigned>(esp_get_free_heap_size()),
@@ -139,12 +152,16 @@ ble_client:
     on_connect:
       then:
         - script.execute: wake_backlight
+        # Notify the custom parser/display object and switch to the meter page when
+        # the OWON connects, so the on-device screen follows the active instrument.
         - lambda: |-
             owon_meter.on_connect();
             id(display_page) = 0;
             id(lcd).update();
     on_disconnect:
       then:
+        # Keep the UI useful after a disconnect: if the Atorch is still online,
+        # automatically fall back from the OWON page to the Atorch page.
         - lambda: |-
             owon_meter.on_disconnect();
             if (id(display_page) == 0 && id(atorch_connected)) {
@@ -153,6 +170,8 @@ ble_client:
             id(lcd).update();
         - if:
             condition:
+              # Start the idle timer only after both BLE clients are gone; otherwise
+              # the remaining connected instrument still deserves an active display.
               lambda: |-
                 return !owon_meter.connected && !id(atorch_connected);
             then:
@@ -163,12 +182,16 @@ ble_client:
     on_connect:
       then:
         - script.execute: wake_backlight
+        # The Atorch component handles measurements, while this explicit flag/page
+        # switch keeps the shared display state synchronized with the BLE client.
         - lambda: |-
             id(atorch_connected) = true;
             id(display_page) = 1;
             id(lcd).update();
     on_disconnect:
       then:
+        # If the load disconnects while the meter is still connected, move the
+        # physical display back to the meter instead of leaving a stale load page.
         - lambda: |-
             id(atorch_connected) = false;
             if (id(display_page) == 1 && owon_meter.connected) {
@@ -177,6 +200,8 @@ ble_client:
             id(lcd).update();
         - if:
             condition:
+              # Same idle rule as OWON disconnect: only dim/off when neither BLE
+              # target is connected anymore.
               lambda: |-
                 return !owon_meter.connected && !id(atorch_connected);
             then:
@@ -203,6 +228,8 @@ output:
     type: float
     id: lcd_backlight
     write_action:
+      # Bridge ESPHome's generic monochromatic light level to the Core2-specific
+      # AXP192 backlight voltage helper implemented in lab-ble-proxy.h.
       - lambda: |-
           owon_b35t::core2_axp192_set_backlight(state);
 
@@ -217,6 +244,8 @@ font:
   - file: "fonts/Roboto-Regular.ttf"
     id: meter_font
     size: 15
+    # Glyphs are whitelisted to save flash/RAM; include symbols used by units,
+    # status labels, soft-button names, and Atorch metric text.
     glyphs:
       [
         " ",
@@ -293,6 +322,7 @@ font:
   - file: "fonts/Roboto-Medium.ttf"
     id: atorch_value_font
     size: 22
+    # Larger Atorch value font only needs numeric characters and measurement units.
     glyphs:
       [
         " ",
@@ -322,6 +352,8 @@ display:
     id: lcd
     model: M5CORE2
     update_interval: 500ms
+    # Rendering is delegated to the custom C++ helper because ESPHome display YAML
+    # primitives would be unwieldy for the OWON seven-segment clone and Atorch dashboard.
     lambda: |-
       owon_meter.render(
         it,
@@ -346,6 +378,8 @@ touchscreen:
         - script.execute: wake_backlight
         - if:
             condition:
+              # Touching an idle/disconnected unit wakes the display briefly, then
+              # restarts the idle timer if no BLE target is available.
               lambda: |-
                 return !owon_meter.connected && !id(atorch_connected);
             then:
@@ -361,6 +395,7 @@ binary_sensor:
     y_max: 195
     on_press:
       then:
+        # The large middle touch zone toggles between the two custom render pages.
         - lambda: |-
             id(display_page) = 1 - id(display_page);
             id(lcd).update();
@@ -374,6 +409,7 @@ binary_sensor:
     internal: true
     on_press:
       then:
+        # Left soft button changes which OWON remote command the center button will send.
         - lambda: |-
             owon_meter.previous_button();
   - platform: touchscreen
@@ -396,6 +432,8 @@ binary_sensor:
               id: owon_ble_client
               service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
               characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+              # OWON remote-control payload: first byte selects the meter button,
+              # second byte selects the normal/short-press action variant.
               value: !lambda |-
                 std::vector<uint8_t> data = {owon_meter.selected_button, 0x01};
                 return data;
@@ -410,6 +448,8 @@ binary_sensor:
               id: owon_ble_client
               service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
               characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+              # Long-press encoding is not uniform: SELECT and HZ/DUTY still use
+              # 0x01, while RANGE/HOLD/REL/MAX-MIN use 0x00 for their alternate action.
               value: !lambda |-
                 uint8_t press_type = (owon_meter.selected_button == 1 || owon_meter.selected_button == 5) ? 0x01 : 0x00;
                 std::vector<uint8_t> data = {owon_meter.selected_button, press_type};
@@ -424,12 +464,14 @@ binary_sensor:
     internal: true
     on_press:
       then:
+        # Right soft button advances to the next OWON command label.
         - lambda: |-
             owon_meter.next_button();
 
   - platform: template
     name: "${friendly_name} OWON Connected"
     icon: "mdi:bluetooth-connect"
+    # Template binary sensors expose state maintained by the custom OWON parser object.
     lambda: |-
       return owon_meter.connected;
   - platform: template
@@ -450,6 +492,8 @@ binary_sensor:
       return id(atorch_connected);
 
 sensor:
+  # This hidden characteristic sensor is the bridge from OWON BLE notifications into
+  # custom C++ parsing. The returned float becomes the source numeric meter reading.
   - platform: ble_client
     type: characteristic
     ble_client_id: owon_ble_client
@@ -488,6 +532,8 @@ sensor:
       name: "${friendly_name} Atorch Dim Backlight"
       id: atorch_dim_backlight
 
+  # The DL24 component exposes power, but this config computes Wh locally so the
+  # accumulated energy can be restored and reset alongside Atorch's own counters.
   - platform: integration
     name: "${friendly_name} Atorch Energy"
     id: atorch_energy_calculated
@@ -506,18 +552,21 @@ text_sensor:
     name: "${friendly_name} OWON Reading"
     update_interval: 1s
     icon: "mdi:gauge"
+    # Human-readable mirror of the meter LCD, including waiting/disconnected/OL states.
     lambda: |-
       return owon_meter.reading_text();
   - platform: template
     name: "${friendly_name} OWON Unit"
     update_interval: 1s
     icon: "mdi:ruler"
+    # Combines SI prefix and unit into one HA text entity, e.g. mV, kΩ, µA, %.
     lambda: |-
       return std::string(owon_meter.scale()) + owon_meter.unit();
   - platform: template
     name: "${friendly_name} OWON Mode"
     icon: "mdi:knob"
     update_interval: 1s
+    # Exposes decoded annunciators such as AC/DC, AUTO, HOLD, REL, MIN/MAX.
     lambda: |-
       return owon_meter.mode_text();
 
@@ -535,6 +584,7 @@ button:
     reset_all:
       name: "${friendly_name} Atorch Reset All"
       on_press:
+        # Keep the locally integrated Wh counter in sync with the DL24 reset-all command.
         - sensor.integration.reset: atorch_energy_calculated
     usb_plus:
       name: "${friendly_name} Atorch Plus"
@@ -544,6 +594,8 @@ button:
       name: "${friendly_name} Atorch Setup"
     enter:
       name: "${friendly_name} Atorch Enter"
+  # Home Assistant button entities for direct OWON remote commands. The payloads
+  # are the same two-byte command format used by the touchscreen soft buttons.
   - platform: template
     name: "OWON SELECT"
     id: owon_btn_select
@@ -552,6 +604,7 @@ button:
           id: owon_ble_client
           service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
           characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+          # SELECT normal press.
           value: !lambda "return std::vector<uint8_t>({1, 0x01});"
 
   - platform: template
@@ -562,6 +615,7 @@ button:
           id: owon_ble_client
           service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
           characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+          # RANGE normal press.
           value: !lambda "return std::vector<uint8_t>({2, 0x01});"
 
   - platform: template
@@ -572,6 +626,7 @@ button:
           id: owon_ble_client
           service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
           characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+          # HOLD is the short/normal action on the shared HLD/LIG physical key.
           value: !lambda "return std::vector<uint8_t>({3, 0x01});"
 
   - platform: template
@@ -582,6 +637,7 @@ button:
           id: owon_ble_client
           service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
           characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+          # LIGHT is the alternate/long action on the same HLD/LIG key.
           value: !lambda "return std::vector<uint8_t>({3, 0x00});"
 
   - platform: template
@@ -592,6 +648,7 @@ button:
           id: owon_ble_client
           service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
           characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+          # RELATIVE is the short/normal action on the shared REL/BT key.
           value: !lambda "return std::vector<uint8_t>({4, 0x01});"
 
   - platform: template
@@ -602,6 +659,7 @@ button:
           id: owon_ble_client
           service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
           characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+          # BT is the alternate/long action on the same REL/BT key.
           value: !lambda "return std::vector<uint8_t>({4, 0x00});"
 
   - platform: template
@@ -612,6 +670,7 @@ button:
           id: owon_ble_client
           service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
           characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+          # HZ/DUTY command uses the normal action variant.
           value: !lambda "return std::vector<uint8_t>({5, 0x01});"
 
   - platform: template
@@ -622,4 +681,5 @@ button:
           id: owon_ble_client
           service_uuid: "0000fff0-0000-1000-8000-00805f9b34fb"
           characteristic_uuid: "0000fff3-0000-1000-8000-00805f9b34fb"
+          # MAX/MIN command uses the normal action variant.
           value: !lambda "return std::vector<uint8_t>({6, 0x01});"