From 94ed17815c64d4469a1b801aa7b2d652788d810d Mon Sep 17 00:00:00 2001
From: mtmatteo79 <74114415+mtmatteo79@users.noreply.github.com>
Date: Thu, 1 Oct 2026 01:55:39 +0200
Subject: [PATCH] [bthome_mithermometer] Decode 0.1C temperature and 1%
 humidity objects (#19956)

---
 .../bthome_mithermometer/bthome_ble.cpp       | 15 +++++
 .../sensor/bthome_objects_test.cpp            | 66 +++++++++++++++++++
 2 files changed, 81 insertions(+)
 create mode 100644 tests/components/bthome_mithermometer/sensor/bthome_objects_test.cpp

diff --git a/esphome/components/bthome_mithermometer/bthome_ble.cpp b/esphome/components/bthome_mithermometer/bthome_ble.cpp
index 1ebabea0a3..51f5d866a4 100644
--- a/esphome/components/bthome_mithermometer/bthome_ble.cpp
+++ b/esphome/components/bthome_mithermometer/bthome_ble.cpp
@@ -422,6 +422,21 @@ bool BTHomeMiThermometer::handle_service_data_(const ble_device_base::ServiceDat
         }
         break;
       }
+      case 0x45: {  // temperature (0.1C), e.g. Shelly BLU H&T
+        if (this->temperature_ != nullptr) {
+          const int16_t raw = encode_uint16(value[1], value[0]);
+          this->temperature_->publish_state(raw * 0.1f);
+          reported = true;
+        }
+        break;
+      }
+      case 0x2E: {  // humidity (uint8, 1%), e.g. Shelly BLU H&T
+        if (this->humidity_ != nullptr) {
+          this->humidity_->publish_state(value[0]);
+          reported = true;
+        }
+        break;
+      }
       default:
         break;
     }
diff --git a/tests/components/bthome_mithermometer/sensor/bthome_objects_test.cpp b/tests/components/bthome_mithermometer/sensor/bthome_objects_test.cpp
new file mode 100644
index 0000000000..e3903212be
--- /dev/null
+++ b/tests/components/bthome_mithermometer/sensor/bthome_objects_test.cpp
@@ -0,0 +1,66 @@
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <initializer_list>
+#include <vector>
+
+#include "esphome/components/bthome_mithermometer/bthome_ble.h"
+
+namespace esphome::bthome_mithermometer::testing {
+
+namespace {
+
+constexpr uint64_t SENSOR_ADDRESS = 0xA4C1384E1678ULL;
+
+// Unencrypted BTHome v2 service data (UUID 0xFCD2) sent from SENSOR_ADDRESS.
+ble_device_base::ESPBTDevice advert(std::initializer_list<uint8_t> service_data) {
+  std::vector<uint8_t> adv = {static_cast<uint8_t>(service_data.size() + 3), 0x16, 0xD2, 0xFC};
+  adv.insert(adv.end(), service_data.begin(), service_data.end());
+  uint8_t mac[6];
+  for (size_t i = 0; i < 6; i++)
+    mac[i] = static_cast<uint8_t>(SENSOR_ADDRESS >> (i * 8));
+  ble_device_base::ESPBTDevice device;
+  device.from_scan_result(mac, -60, 0, adv.data(), static_cast<uint16_t>(adv.size()));
+  return device;
+}
+
+struct Harness {
+  Harness() {
+    this->thermometer.set_address(SENSOR_ADDRESS);
+    this->thermometer.set_temperature(&this->temperature);
+    this->thermometer.set_humidity(&this->humidity);
+    this->thermometer.set_battery_level(&this->battery_level);
+  }
+
+  BTHomeMiThermometer thermometer;
+  sensor::Sensor temperature, humidity, battery_level;
+};
+
+}  // namespace
+
+// Shelly BLU H&T: packet id, battery 90 %, humidity 55 % (0x2E), temperature 22.5 C (0x45)
+TEST(BTHomeMiThermometerObjects, DecodesShellyStyleTemperatureAndHumidity) {
+  Harness h;
+  ASSERT_TRUE(h.thermometer.parse_device(advert({0x40, 0x00, 0x01, 0x01, 0x5A, 0x2E, 0x37, 0x45, 0xE1, 0x00})));
+  EXPECT_NEAR(h.temperature.state, 22.5f, 0.001f);
+  EXPECT_FLOAT_EQ(h.humidity.state, 55.0f);
+  EXPECT_FLOAT_EQ(h.battery_level.state, 90.0f);
+}
+
+TEST(BTHomeMiThermometerObjects, DecodesNegativeTenthDegreeTemperature) {
+  Harness h;
+  // -5.3 C = -53 = 0xFFCB
+  ASSERT_TRUE(h.thermometer.parse_device(advert({0x40, 0x45, 0xCB, 0xFF})));
+  EXPECT_NEAR(h.temperature.state, -5.3f, 0.001f);
+  EXPECT_FALSE(h.humidity.has_state());
+}
+
+// PVVX firmware: temperature 22.50 C (0x02) and humidity 45.67 % (0x03) keep working
+TEST(BTHomeMiThermometerObjects, StillDecodesHundredthDegreeObjects) {
+  Harness h;
+  ASSERT_TRUE(h.thermometer.parse_device(advert({0x40, 0x02, 0xCA, 0x08, 0x03, 0xD7, 0x11})));
+  EXPECT_NEAR(h.temperature.state, 22.5f, 0.001f);
+  EXPECT_NEAR(h.humidity.state, 45.67f, 0.001f);
+}
+
+}  // namespace esphome::bthome_mithermometer::testing