diff --git a/firmware/components/sensors.yaml b/firmware/components/sensors.yaml
index 743aa57..54e3e96 100644
--- a/firmware/components/sensors.yaml
+++ b/firmware/components/sensors.yaml
@@ -1 +1,14 @@
-# placeholder — see task 3/4/5/6
+sensor:
+  - platform: bme280_i2c
+    i2c_id: i2c_bus         # shared bus declared in display.yaml — GPIO8 SDA / GPIO9 SCL
+    address: 0x76            # BME280 default; try 0x77 if SDO is pulled high
+    update_interval: 30s
+    temperature:
+      name: "Ambient Temperature"
+      id: bme280_temperature
+    humidity:
+      name: "Ambient Humidity"
+      id: bme280_humidity
+    pressure:
+      name: "Ambient Pressure"
+      id: bme280_pressure