Initial release: ESP32-C3 CO2 & environment sensor board

KiCad 10 design (schematic, 2-layer layout, custom symbols and footprints),
fabrication data for PCBWay (Gerber X2, Excellon, job file), BOM, generated
documentation (schematic PDF, layer plots, 3D render) and firmware notes.

.gitignore

@@ -0,0 +1,15 @@
+# KiCad local history and backups (local only, not part of the design)
+.history/
+_restore_backup_*/
+-backups/
+*.bak
+*.kicad_prl
+
+# Generated fabrication outputs are published in gerber/ ; keep ad-hoc exports out
+*.gbr.bak
+*.drl.bak
+
+# OS / editor noise
+.DS_Store
+*~
+*.swp

README.md

@@ -0,0 +1,161 @@
+# ESP32-C3 CO₂ & Environment Sensor Board
+
+A small environmental monitoring board: **ESP32-C3** module with a **Sensirion S8** NDIR CO₂ sensor
+(UART) and a **BME280** temperature / humidity / pressure sensor (I²C). Flashed with ESPHome and
+integrated into Home Assistant.
+
+**Status:** prototype v1 — designed in KiCad, fabricated at PCBWay, hand assembled, powered up and
+running.
+
+| | |
+|---|---|
+| Board size | 50.05 × 40.05 mm |
+| Layers | 2 |
+| Assembly | through-hole / pin-header plug-in modules |
+| Firmware | ESPHome (see [`firmware/`](firmware/)) |
+| Schematic | [`docs/esp-sensair-schematic.pdf`](docs/esp-sensair-schematic.pdf) |
+| Fabrication data | [`gerber/`](gerber/) (Gerber X2 + Excellon + ODB job) |
+
+![3D render](docs/esp-sensair-3d-top.png)
+
+## Block diagram
+
+```
+                              +5 V
+                                |
+      +-------------------------+---------------------------+
+      |                         |                           |
+      |              +----------v----------+                 |
+      |              |   ESP32-C3 module   |--- 3.3 V out --+|
+      |              | (onboard 3V3 LDO)   |                ||
+      +--------------+                     |                ||
+      |  UART 9600   +----------+----------+                ||
+      |                        |                           ||
++-----v-------+         +------v-------+                    v
+| Sensirion S8|         |    BME280    |<--- I2C (SDA/SCL) --+
+|  NDIR CO2   |         |  T / RH / P  |
++-------------+         +--------------+
+
+SW1 (calibration button) -- RC debounce (1 k / 100 n) -- ESP32-C3 GPIO
+```
+
+## Connections
+
+| Signal | ESP32-C3 module | Sensirion S8 | BME280 |
+|---|---|---|---|
+| `+5V` | pad 11 | pad 0 (heater supply) | — |
+| `GND` | pad 12 | pad 1 | pads 0, 4 |
+| `+3V3` | pad 13 (module output) | — | pads 1, 5 |
+| `/TX` | pad 21 | pad 6 (`UART_RxD`) | — |
+| `/RX` | pad 20 | pad 5 (`UART_TxD`) | — |
+| `/SDA` | pad 7 | — | pad 2 |
+| `/SCL` | pad 8 | — | pad 3 |
+| `bCal_in` | — | pad 8 (`bCal_in`) | — |
+
+Sensirion S8 pins `Alarm_OC`, `PWM_1kHz`, `DVCC_out` and `UART_R/T` are left unconnected.
+
+## Bill of materials
+
+| Ref | Part | Package | Function |
+|---|---|---|---|
+| U1 | ESP32-C3 Wi-Fi/BLE module (16 pads) | custom `esp_sensair_stuff:ESP32-C3` | MCU, radio, 3.3 V regulator on module |
+| U2 | Sensirion S8 NDIR CO₂ sensor | custom `esp_sensair_stuff:Sensair S8` | CO₂ measurement, UART, 5 V heater |
+| U3 | BME280 (plug-in breakout) | custom `esp_sensair_stuff:BME280` | temperature, relative humidity, pressure, I²C |
+| SW1 | Tactile push button 6 mm | `Button_Switch_THT:SW_PUSH_6mm` | S8 manual (background) calibration trigger |
+| R1 | 1 kΩ | `Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal` | button debounce, low-pass to GND |
+| C1 | 100 nF | `Capacitor_THT:C_Disc_D10.5mm_W5.0mm_P5.00mm` | button debounce / supply decoupling |
+
+Machine-readable BOM: [`bom/esp-sensair-bom.csv`](bom/esp-sensair-bom.csv)
+
+## Fabrication
+
+Order data used for the v1 prototype:
+
+| Parameter | Value |
+|---|---|
+| Fabricator | PCBWay |
+| Layers | 2 |
+| Board size (ordered) | 40 × 50 mm |
+| Board size (design) | 40.05 × 50.05 mm |
+| Board material | FR-4 |
+| Board thickness | 1.6 mm |
+| Finished copper weight | 1 oz (35 µm) |
+| Surface finish | HASL with lead |
+| Design rules used | 0.15 mm track / 0.15 mm clearance, via 0.7 mm / 0.3 mm drill |
+| Drill sizes present | 0.8 mm, 1.0 mm, 1.1 mm (39 plated holes, 4 vias) |
+| Non-plated holes | none |
+| Solder mask / silkscreen | as ordered (see `gerber/`) |
+| Stencil | not ordered (THT assembly) |
+| Qty / lead time / cost | _fill in from your order confirmation_ |
+
+Fabrication files:
+
+- `gerber/esp-sensair.zip` — Gerber X2 plot + drill files, ready to upload
+- `gerber/esp+sensair-job.gbrjob` — Gerber job / stackup description
+
+> **Note on the job file:** the v1 project was started from a 4-layer KiCad stackup, so
+> `esp+sensair-job.gbrjob` declares `LayerNumber: 4` and labels the copper layers `L1`/`L4` even
+> though only the outer layers are used. The board was fabricated correctly as a 2-layer board.
+> For the next revision: set the stackup to 2 layers in *Board Setup → Stackup* before exporting,
+> so the job file is self-consistent for anyone re-ordering the board.
+
+## Assembly
+
+All parts are through-hole or plug-in modules on pin headers; hand soldered with a soldering iron.
+The Sensirion S8 requires a 5 V supply (its NDIR heater draws current pulses of up to ~150 mA) and
+about 30 s of preheat time before it reports valid CO₂ values.
+
+## Firmware
+
+ESPHome, see [`firmware/`](firmware/) for the config and the Home Assistant wiring.
+S8 UART: 9600 baud, 8N1. BME280 I²C: standard address `0x76` (or `0x77` depending on the breakout).
+
+## Known issues and lessons learned (v1 → v2)
+
+1. **No copper pours.** Neither layer has a ground plane. v2: solid GND pour on the bottom layer
+   with stitching vias around the ESP32-C3 module.
+2. **No mounting holes.** The board is held by its connectors only. v2: four M2.5 holes.
+3. **No I²C pull-ups populated.** The design relies on the pull-ups of the BME280 breakout.
+   v2: add 4.7 kΩ pull-up footprints on `SDA`/`SCL`.
+4. **Single 100 nF decoupling capacitor** for the whole board. v2: 100 nF per supply pin plus a
+   10–100 µF bulk capacitor close to the S8 heater supply, which is the actual current-pulse source.
+5. **Schematic is not annotated** (references `U`, `U`, `U`), so KiCad BOM export is unusable.
+   v2: annotate, set MPNs, and export the BOM from the schematic.
+6. **Leaded HASL** is not RoHS-compliant. v2: HASL lead-free, and ENIG for any impedance-controlled
+   design.
+7. **Project name contains `+`.** It propagates into the Gerber file names (`esp+sensair-Front.gbr`),
+   which some fabricator upload portals and drill parsers reject. v2: `esp-sensair`.
+8. **Antenna keep-out** for the ESP32-C3 module should be checked explicitly against the module
+   datasheet (no copper, no silkscreen, no vias under the antenna area).
+
+## Repository layout
+
+```
+.
+├── esp+sensair.kicad_pro        KiCad project
+├── esp+sensair.kicad_sch        schematic
+├── esp+sensair.kicad_pcb        board layout
+├── esp_sensair_stuff.kicad_sym  custom symbols (ESP32-C3, Sensirion S8, BME280)
+├── esp_sensair_stuff.pretty/    custom footprints, drawn from component datasheets
+├── fp-lib-table                 project-local footprint library table (${KIPRJMOD})
+├── gerber/                      Gerber X2, Excellon drills, job file, ready-to-upload zip
+├── bom/                         bill of materials (CSV)
+├── docs/                        schematic PDF, layer plots, 3D render
+├── firmware/                    ESPHome configuration
+└── photos/                      photographs of the assembled board
+```
+
+## Rebuilding the board
+
+1. Open `esp+sensair.kicad_pro` in KiCad 10.
+2. Run DRC; fix anything you change.
+3. Export Gerbers/drill (the settings are stored in the project) and upload `gerber/*.zip` to your
+   fabricator with the parameters from the fabrication table.
+4. Order parts per BOM, solder through-hole parts and pin headers.
+5. Flash the ESPHome configuration and add the device to Home Assistant.
+
+## License
+
+Not chosen yet. Recommended for a published open-hardware module:
+**CERN-OHL-S-2.0** for the hardware (schematic, layout, footprints) and **MIT** for the firmware
+configuration and scripts. A `LICENSE` file must be added before publishing.

bom/esp-sensair-bom.csv

@@ -0,0 +1,7 @@
+Reference,Qty,Part,Manufacturer,Package,Value,Function
+U1,1,ESP32-C3 Wi-Fi/BLE module,Espressif,custom ESP32-C3 (16 THT pads),,MCU with onboard 3.3 V regulator
+U2,1,S8 NDIR CO2 sensor,Sensirion,custom Sensair S8 (9 THT pads),,CO2 measurement (UART, 5 V heater)
+U3,1,BME280,TDK InvenSense,custom BME280 plug-in (6 THT pads),,Temperature / humidity / pressure (I2C)
+SW1,1,Tactile push button 6 mm,generic,Button_Switch_THT:SW_PUSH_6mm,,S8 calibration trigger
+R1,1,Resistor 1 kOhm 0.25 W,generic,Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P7.62mm_Horizontal,1k,Button debounce
+C1,1,Ceramic capacitor 100 nF,generic,Capacitor_THT:C_Disc_D10.5mm_W5.0mm_P5.00mm,100n,Button debounce / decoupling

esp+sensair.kicad_pro

@@ -0,0 +1,717 @@
+{
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+      "bus_definition_conflict": "error",
+      "bus_entry_needed": "error",
+      "bus_to_bus_conflict": "error",
+      "bus_to_net_conflict": "error",
+      "different_unit_footprint": "error",
+      "different_unit_net": "error",
+      "duplicate_reference": "error",
+      "duplicate_sheet_names": "error",
+      "endpoint_off_grid": "warning",
+      "extra_units": "error",
+      "field_name_whitespace": "warning",
+      "footprint_filter": "ignore",
+      "footprint_link_issues": "warning",
+      "four_way_junction": "ignore",
+      "ground_pin_not_ground": "warning",
+      "hier_label_mismatch": "error",
+      "isolated_pin_label": "warning",
+      "label_dangling": "error",
+      "label_multiple_wires": "warning",
+      "lib_symbol_issues": "warning",
+      "lib_symbol_mismatch": "warning",
+      "missing_bidi_pin": "warning",
+      "missing_input_pin": "warning",
+      "missing_power_pin": "error",
+      "missing_unit": "warning",
+      "multiple_net_names": "warning",
+      "net_not_bus_member": "warning",
+      "no_connect_connected": "warning",
+      "no_connect_dangling": "warning",
+      "pin_not_connected": "error",
+      "pin_not_driven": "error",
+      "pin_to_pin": "error",
+      "power_pin_not_driven": "error",
+      "same_local_global_label": "warning",
+      "similar_label_and_power": "warning",
+      "similar_labels": "warning",
+      "similar_power": "warning",
+      "simulation_model_issue": "ignore",
+      "single_global_label": "ignore",
+      "stacked_pin_name": "warning",
+      "unannotated": "error",
+      "unconnected_wire_endpoint": "warning",
+      "undefined_netclass": "error",
+      "unit_value_mismatch": "error",
+      "unresolved_variable": "error",
+      "wire_dangling": "error"
+    }
+  },
+  "libraries": {
+    "pinned_footprint_libs": [
+      "esp_sensair_stuff"
+    ],
+    "pinned_symbol_libs": [
+      "esp_sensair_stuff"
+    ]
+  },
+  "meta": {
+    "filename": "esp+sensair.kicad_pro",
+    "version": 3
+  },
+  "net_settings": {
+    "classes": [
+      {
+        "bus_width": 12,
+        "clearance": 0.15,
+        "diff_pair_gap": 0.254,
+        "diff_pair_via_gap": 0.25,
+        "diff_pair_width": 0.1524,
+        "line_style": 0,
+        "microvia_diameter": 0.6858,
+        "microvia_drill": 0.3302,
+        "name": "Default",
+        "pcb_color": "rgba(0, 0, 0, 0.000)",
+        "priority": 2147483647,
+        "schematic_color": "rgba(0, 0, 0, 0.000)",
+        "track_width": 0.15,
+        "tuning_profile": "",
+        "via_diameter": 0.7,
+        "via_drill": 0.3,
+        "wire_width": 6
+      }
+    ],
+    "meta": {
+      "version": 5
+    },
+    "net_colors": {},
+    "netclass_assignments": {},
+    "netclass_patterns": []
+  },
+  "pcbnew": {
+    "last_paths": {
+      "idf": "",
+      "netlist": "./",
+      "plot": "",
+      "specctra_dsn": "",
+      "step": "",
+      "vrml": ""
+    },
+    "page_layout_descr_file": ""
+  },
+  "schematic": {
+    "annotate_start_num": 0,
+    "annotation": {
+      "method": 0,
+      "sort_order": 0
+    },
+    "bom_export_filename": "${PROJECTNAME}.csv",
+    "bom_fmt_presets": [],
+    "bom_fmt_settings": {
+      "field_delimiter": ",",
+      "keep_line_breaks": false,
+      "keep_tabs": false,
+      "name": "CSV",
+      "ref_delimiter": ",",
+      "ref_range_delimiter": "",
+      "string_delimiter": "\""
+    },
+    "bom_presets": [],
+    "bom_settings": {
+      "exclude_dnp": false,
+      "fields_ordered": [
+        {
+          "group_by": false,
+          "label": "Reference",
+          "name": "Reference",
+          "show": true
+        },
+        {
+          "group_by": false,
+          "label": "Qty",
+          "name": "${QUANTITY}",
+          "show": true
+        },
+        {
+          "group_by": true,
+          "label": "Value",
+          "name": "Value",
+          "show": true
+        },
+        {
+          "group_by": true,
+          "label": "DNP",
+          "name": "${DNP}",
+          "show": true
+        },
+        {
+          "group_by": true,
+          "label": "Exclude from BOM",
+          "name": "${EXCLUDE_FROM_BOM}",
+          "show": true
+        },
+        {
+          "group_by": true,
+          "label": "Exclude from Board",
+          "name": "${EXCLUDE_FROM_BOARD}",
+          "show": true
+        },
+        {
+          "group_by": true,
+          "label": "Exclude from Simulation",
+          "name": "${EXCLUDE_FROM_SIM}",
+          "show": true
+        },
+        {
+          "group_by": true,
+          "label": "Exclude from Position Files",
+          "name": "${EXCLUDE_FROM_POS_FILES}",
+          "show": true
+        },
+        {
+          "group_by": true,
+          "label": "Footprint",
+          "name": "Footprint",
+          "show": true
+        },
+        {
+          "group_by": false,
+          "label": "Datasheet",
+          "name": "Datasheet",
+          "show": true
+        }
+      ],
+      "filter_string": "",
+      "group_symbols": true,
+      "include_excluded_from_bom": true,
+      "name": "Default Editing",
+      "sort_asc": true,
+      "sort_field": "Reference"
+    },
+    "bus_aliases": {},
+    "connection_grid_size": 50.0,
+    "drawing": {
+      "dashed_lines_dash_length_ratio": 12.0,
+      "dashed_lines_gap_length_ratio": 3.0,
+      "default_line_thickness": 6.0,
+      "default_text_size": 50.0,
+      "field_names": [],
+      "hop_over_size_choice": 0,
+      "intersheets_ref_own_page": false,
+      "intersheets_ref_prefix": "",
+      "intersheets_ref_short": false,
+      "intersheets_ref_show": false,
+      "intersheets_ref_suffix": "",
+      "junction_size_choice": 3,
+      "label_size_ratio": 0.375,
+      "operating_point_overlay_i_precision": 3,
+      "operating_point_overlay_i_range": "~A",
+      "operating_point_overlay_v_precision": 3,
+      "operating_point_overlay_v_range": "~V",
+      "overbar_offset_ratio": 1.23,
+      "pin_symbol_size": 25.0,
+      "text_offset_ratio": 0.15
+    },
+    "legacy_lib_dir": "",
+    "legacy_lib_list": [],
+    "meta": {
+      "version": 1
+    },
+    "ngspice": {
+      "fix_include_paths": true,
+      "meta": {
+        "version": 0
+      },
+      "model_mode": 4,
+      "workbook_filename": ""
+    },
+    "page_layout_descr_file": "",
+    "plot_directory": "",
+    "reuse_designators": true,
+    "subpart_first_id": 65,
+    "subpart_id_separator": 0,
+    "top_level_sheets": [
+      {
+        "filename": "esp+sensair.kicad_sch",
+        "name": "Root",
+        "uuid": "d19c68d2-fb5a-4249-a650-17ae87065123"
+      }
+    ],
+    "used_designators": "C1,R1,J1-7,SW1,#PWR1-12,U1-3",
+    "variants": []
+  },
+  "sheets": [
+    [
+      "d19c68d2-fb5a-4249-a650-17ae87065123",
+      "Root"
+    ]
+  ],
+  "text_variables": {},
+  "tuning_profiles": {
+    "meta": {
+      "version": 0
+    },
+    "tuning_profiles_impedance_geometric": []
+  }
+}

esp_sensair_stuff.kicad_sym

@@ -0,0 +1,791 @@
+(kicad_symbol_lib
+	(version 20251024)
+	(generator "kicad_symbol_editor")
+	(generator_version "10.0")
+	(symbol "BME280-plug-in"
+		(exclude_from_sim no)
+		(in_bom yes)
+		(on_board yes)
+		(in_pos_files yes)
+		(duplicate_pin_numbers_are_jumpers no)
+		(property "Reference" "U"
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Value" "BME280"
+			(at -9.144 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Footprint" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Datasheet" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Description" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(symbol "BME280-plug-in_0_1"
+			(rectangle
+				(start -5.08 7.62)
+				(end 5.08 -7.62)
+				(stroke
+					(width 0)
+					(type default)
+				)
+				(fill
+					(type none)
+				)
+			)
+		)
+		(symbol "BME280-plug-in_1_1"
+			(pin input line
+				(at 7.62 3.81 180)
+				(length 2.54)
+				(name "SD0"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "0"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin input line
+				(at 7.62 1.27 180)
+				(length 2.54)
+				(name "CSB"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "1"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin bidirectional line
+				(at 7.62 -1.27 180)
+				(length 2.54)
+				(name "SDA"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "2"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin input line
+				(at 7.62 -3.81 180)
+				(length 2.54)
+				(name "SCL"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "3"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin power_in line
+				(at 0 -10.16 90)
+				(length 2.54)
+				(name "GND"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "4"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin power_in line
+				(at 0 10.16 270)
+				(length 2.54)
+				(name "3V3"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "5"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+		)
+		(embedded_fonts no)
+	)
+	(symbol "ESP32-C3-plug-in"
+		(exclude_from_sim no)
+		(in_bom yes)
+		(on_board yes)
+		(in_pos_files yes)
+		(duplicate_pin_numbers_are_jumpers no)
+		(property "Reference" "U"
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Value" "ESP32-C3"
+			(at 0 -9.144 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Footprint" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Datasheet" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Description" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(symbol "ESP32-C3-plug-in_0_1"
+			(rectangle
+				(start -7.62 10.16)
+				(end 7.62 -10.16)
+				(stroke
+					(width 0)
+					(type default)
+				)
+				(fill
+					(type none)
+				)
+			)
+		)
+		(symbol "ESP32-C3-plug-in_1_1"
+			(pin bidirectional line
+				(at 10.16 -8.89 180)
+				(length 2.54)
+				(name "0"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "0"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin bidirectional line
+				(at 10.16 -6.35 180)
+				(length 2.54)
+				(name "1"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "1"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin bidirectional line
+				(at 10.16 -3.81 180)
+				(length 2.54)
+				(name "2"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "2"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin bidirectional line
+				(at 10.16 -1.27 180)
+				(length 2.54)
+				(name "3"
+					(effects
+						(font
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+						)
+					)
+				)
+				(number "3"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin bidirectional line
+				(at 10.16 1.27 180)
+				(length 2.54)
+				(name "4"
+					(effects
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+						)
+					)
+				)
+				(number "4"
+					(effects
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+					)
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+			)
+			(pin bidirectional line
+				(at -10.16 8.89 0)
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+					)
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+					)
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+				(length 2.54)
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+					)
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+			)
+			(pin bidirectional line
+				(at -10.16 -3.81 0)
+				(length 2.54)
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+						)
+					)
+				)
+				(number "10"
+					(effects
+						(font
+							(size 1.27 1.27)
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+					)
+				)
+			)
+			(pin power_in line
+				(at 10.16 8.89 180)
+				(length 2.54)
+				(name "5V"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "11"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin power_in line
+				(at 10.16 6.35 180)
+				(length 2.54)
+				(name "GND"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "12"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin power_out line
+				(at 10.16 3.81 180)
+				(length 2.54)
+				(name "3V3"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "13"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin bidirectional line
+				(at -10.16 -6.35 0)
+				(length 2.54)
+				(name "20"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "20"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+			(pin bidirectional line
+				(at -10.16 -8.89 0)
+				(length 2.54)
+				(name "21"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+				(number "21"
+					(effects
+						(font
+							(size 1.27 1.27)
+						)
+					)
+				)
+			)
+		)
+		(embedded_fonts no)
+	)
+	(symbol "Sensair-S8-Plug-in"
+		(exclude_from_sim no)
+		(in_bom yes)
+		(on_board yes)
+		(in_pos_files yes)
+		(duplicate_pin_numbers_are_jumpers no)
+		(property "Reference" "U"
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Value" "Sensair-S8"
+			(at -0.254 -9.144 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Footprint" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Datasheet" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(property "Description" ""
+			(at 0 0 0)
+			(show_name no)
+			(do_not_autoplace no)
+			(hide yes)
+			(effects
+				(font
+					(size 1.27 1.27)
+				)
+			)
+		)
+		(symbol "Sensair-S8-Plug-in_0_1"
+			(rectangle
+				(start -10.16 10.16)
+				(end 10.16 -10.16)
+				(stroke
+					(width 0)
+					(type default)
+				)
+				(fill
+					(type none)
+				)
+			)
+		)
+		(symbol "Sensair-S8-Plug-in_1_1"
+			(pin power_in line
+				(at -12.7 6.35 0)
+				(length 2.54)
+				(name "5V"
+					(effects
+						(font
+							(size 1.27 1.27)
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+					)
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+				(number "0"
+					(effects
+						(font
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+						)
+					)
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+			(pin power_in line
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+				(length 2.54)
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+					(effects
+						(font
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+				)
+				(number "1"
+					(effects
+						(font
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+			(pin no_connect line
+				(at -12.7 -2.54 0)
+				(length 2.54)
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+						(font
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+						)
+					)
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+				(number "2"
+					(effects
+						(font
+							(size 1.27 1.27)
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+				)
+			)
+			(pin no_connect line
+				(at -12.7 -6.35 0)
+				(length 2.54)
+				(name "PWM_1kHz"
+					(effects
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+						)
+					)
+				)
+				(number "3"
+					(effects
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+			(pin no_connect line
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+			(pin input line
+				(at 12.7 3.81 180)
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+					(effects
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+				(number "5"
+					(effects
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+				(at 12.7 0 180)
+				(length 2.54)
+				(name "UART_TxD"
+					(effects
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+					)
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+				(number "6"
+					(effects
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+			(pin no_connect line
+				(at 12.7 -3.81 180)
+				(length 2.54)
+				(name "UART_R/T"
+					(effects
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+					)
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+				(number "7"
+					(effects
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+			)
+			(pin input line
+				(at 12.7 -7.62 180)
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+					(effects
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+				(number "8"
+					(effects
+						(font
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+					)
+				)
+			)
+		)
+		(embedded_fonts no)
+	)
+)

esp_sensair_stuff.pretty/BME280.kicad_mod

@@ -0,0 +1,243 @@
+(footprint "BME280"
+	(version 20260206)
+	(generator "pcbnew")
+	(generator_version "10.0")
+	(layer "F.Cu")
+	(property "Reference" "REF**"
+		(at 3.3 8.2 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "0c66aec5-8a1a-4da8-b390-d0721d915622")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+		)
+	)
+	(property "Value" "BME280"
+		(at 0 1 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(uuid "658ed8c8-9365-4671-b0d9-2dc5ebfce178")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(property "Datasheet" ""
+		(at 0 0 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(hide yes)
+		(uuid "06e6cad0-970f-4f82-83fe-d0fe7e731d05")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(property "Description" ""
+		(at 0 0 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(hide yes)
+		(uuid "012f2eb9-98c3-4d69-9bfc-5535812a22bb")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(attr smd)
+	(duplicate_pad_numbers_are_jumpers no)
+	(fp_rect
+		(start -5.35 -7.5)
+		(end 5.35 7.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(fill no)
+		(layer "F.SilkS")
+		(uuid "45df38fe-fcde-4152-8510-181d11b2c62d")
+	)
+	(fp_text user "SDA"
+		(at 3.6 -0.6 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "04a01547-e6e6-4661-a057-786d77c9f7d8")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify right bottom)
+		)
+	)
+	(fp_text user "SD0"
+		(at 3.7 -5.7 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "3bb453b1-b0ca-4cbc-9578-8db4dfb9c533")
+		(effects
+			(font
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+		(at 3.7 -3.1 0)
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+		(uuid "45af1f45-b5a7-42f2-a946-b6e9dd9252f1")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify right bottom)
+		)
+	)
+	(fp_text user "SCL"
+		(at 3.7 1.9 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "59fad60f-e307-4788-bf6c-7f0326f7f6c4")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
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+			(justify right bottom)
+		)
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+		(unlocked yes)
+		(layer "F.SilkS")
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+		(effects
+			(font
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+		(effects
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+		)
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+	(fp_text user "${REFERENCE}"
+		(at 0 2.5 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(uuid "3ccb3a1b-11dd-4b9a-8621-60a9f27c863b")
+		(effects
+			(font
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+				(thickness 0.15)
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+		)
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+	(pad "0" thru_hole roundrect
+		(at 4.44 -6.35)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "4cee3a06-5372-4aba-85f2-66017f742b41")
+	)
+	(pad "1" thru_hole roundrect
+		(at 4.44 -3.81)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "a4e2b9c0-addd-414b-ad2c-403d84cc0f4a")
+	)
+	(pad "2" thru_hole roundrect
+		(at 4.44 -1.27)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "45733ace-2c8d-4ca9-9abe-5eeff998230e")
+	)
+	(pad "3" thru_hole roundrect
+		(at 4.44 1.27)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "911967b3-a51d-4c14-a30c-f93dc996c274")
+	)
+	(pad "4" thru_hole rect
+		(at 4.44 3.81)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(uuid "43ca01a1-1ac5-475a-9a19-0d514b2c3d6f")
+	)
+	(pad "5" thru_hole circle
+		(at 4.44 6.35)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(thermal_bridge_angle 90)
+		(uuid "9e88efde-b8e2-48d7-acf9-9058d5dc8a45")
+	)
+	(zone
+		(layer "F.SilkS")
+		(uuid "9d32a799-ee3e-4eab-ba36-fa0325100fe5")
+		(hatch edge 0.5)
+		(connect_pads
+			(clearance 0)
+		)
+		(min_thickness 0.25)
+		(keepout
+			(tracks allowed)
+			(vias allowed)
+			(pads not_allowed)
+			(copperpour allowed)
+			(footprints not_allowed)
+		)
+		(placement
+			(enabled no)
+			(sheetname "")
+		)
+		(fill
+			(thermal_gap 0.5)
+			(thermal_bridge_width 0.5)
+			(island_removal_mode 0)
+		)
+		(polygon
+			(pts
+				(xy -5.35 -7.5) (xy -5.35 7.5) (xy 5.35 7.5) (xy 5.35 -7.5)
+			)
+		)
+	)
+	(embedded_fonts no)
+)

esp_sensair_stuff.pretty/ESP32-C3.kicad_mod

@@ -0,0 +1,474 @@
+(footprint "ESP32-C3"
+	(version 20260206)
+	(generator "pcbnew")
+	(generator_version "10.0")
+	(layer "F.Cu")
+	(property "Reference" "REF**"
+		(at 6.985 12.7 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "67e62b4c-cf19-4529-97ae-4184bd53c369")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+		)
+	)
+	(property "Value" "ESP32-C3"
+		(at 0 1 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(uuid "ed33dc66-0b67-4d77-8d12-b252ca297820")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(property "Datasheet" ""
+		(at 0 0 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(hide yes)
+		(uuid "7509f94b-b17e-49ab-9efc-25f4c6e2909b")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(property "Description" ""
+		(at 0 0 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(hide yes)
+		(uuid "3e538944-ff1b-4de5-9f05-058b757eaf31")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(attr smd)
+	(duplicate_pad_numbers_are_jumpers no)
+	(fp_rect
+		(start -9 -11.5)
+		(end 9 11.2)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(fill no)
+		(layer "F.SilkS")
+		(uuid "f2c86894-e460-4d88-b151-83b05372a7cc")
+	)
+	(fp_rect
+		(start -7 -23.5)
+		(end 7 -11.5)
+		(stroke
+			(width 0.05)
+			(type default)
+		)
+		(fill no)
+		(layer "Edge.Cuts")
+		(uuid "f6486428-7a04-483f-a87d-d4505fb8e076")
+	)
+	(fp_text user "5"
+		(at -6.675 -9.144 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "641a4eb3-7f09-4d36-8a95-d81656eea776")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "6"
+		(at -6.675 -6.579 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "c4d8755e-2c42-4908-ae1a-7116f58a03be")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "7"
+		(at -6.675 -4.039 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "dfed05a2-b006-44f0-a3a8-6821b1e4409d")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "8"
+		(at -6.675 -1.499 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "29e7fe22-79e7-4b49-bbea-49752c7f1064")
+		(effects
+			(font
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+	(fp_text user "9"
+		(at -6.675 1.041 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "7437fc67-b2fe-4a64-82c6-963e8450e1d6")
+		(effects
+			(font
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+		)
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+	(fp_text user "10"
+		(at -6.675 3.581 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "88a1e96d-8f34-4364-9f42-7e335e379720")
+		(effects
+			(font
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+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "20"
+		(at -6.675 6.121 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "dfbce507-6cdf-4d14-94c6-490bcd09826a")
+		(effects
+			(font
+				(size 1 1)
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+		)
+	)
+	(fp_text user "21"
+		(at -6.675 8.661 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "0c5a01f6-d9ce-4b0f-b44d-861a080ef82f")
+		(effects
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+		(uuid "9b4774b0-40df-426c-ab8f-5e0260baf5af")
+		(effects
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+		(at 6.604 -6.579 0)
+		(unlocked yes)
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+		(uuid "9153476b-92ab-408c-8be7-8de1f99daff8")
+		(effects
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+	)
+	(fp_text user "3V3"
+		(at 6.604 -4.039 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "61d3c43b-32d9-4c1a-adae-12a9996b4aeb")
+		(effects
+			(font
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+		)
+	)
+	(fp_text user "4"
+		(at 6.604 -1.499 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "77c156db-5128-4eb8-b924-e3860a7f884b")
+		(effects
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+	)
+	(fp_text user "2"
+		(at 6.604 3.581 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "0528fcd7-b5a6-46ee-af9d-b887b493de96")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify right bottom)
+		)
+	)
+	(fp_text user "1"
+		(at 6.604 6.121 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "87de232f-deba-40ab-87d2-37e9029e350e")
+		(effects
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+	(fp_text user "0"
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+		(uuid "fef757e5-07ad-473a-9d3c-7de10287d4a4")
+		(effects
+			(font
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+		)
+	)
+	(fp_text user "${REFERENCE}"
+		(at 0 2.5 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(uuid "eee234ee-4723-4765-9be9-4675967c5341")
+		(effects
+			(font
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+				(thickness 0.15)
+			)
+		)
+	)
+	(pad "0" thru_hole roundrect
+		(at 7.62 8.02)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "5b008f66-97e2-4ec5-99fa-9b4fc5a37559")
+	)
+	(pad "1" thru_hole roundrect
+		(at 7.62 5.48)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "0d03f4e1-7846-43fa-8650-6b5f366a5b0f")
+	)
+	(pad "2" thru_hole roundrect
+		(at 7.62 2.94)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "1285ffc7-fadc-4fa1-9253-e3de9b3d5ab7")
+	)
+	(pad "3" thru_hole roundrect
+		(at 7.62 0.4)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "86b4d665-88d1-4d9c-8bd0-68b22cc6ee55")
+	)
+	(pad "4" thru_hole roundrect
+		(at 7.62 -2.14)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "06377a08-c5aa-4a85-bef7-e7e4ac2a77a4")
+	)
+	(pad "5" thru_hole roundrect
+		(at -7.62 -9.76)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "f44ca30e-3e82-4e86-a30d-4de4f274d40f")
+	)
+	(pad "6" thru_hole roundrect
+		(at -7.62 -7.22)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "a9598c26-ab62-4914-bb26-998a2b0e01e2")
+	)
+	(pad "7" thru_hole roundrect
+		(at -7.62 -4.68)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "03cce8e4-1c17-4807-98c2-679b1d4d10cb")
+	)
+	(pad "8" thru_hole roundrect
+		(at -7.62 -2.14)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "1f1b00b9-a67b-48f7-ae56-d51d7d7a96b6")
+	)
+	(pad "9" thru_hole roundrect
+		(at -7.62 0.4)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "dd462c5a-7062-46c6-80bb-586c0363d8fa")
+	)
+	(pad "10" thru_hole roundrect
+		(at -7.62 2.94)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "a0ac2c0c-f657-4821-b706-fad57dce35d4")
+	)
+	(pad "11" thru_hole circle
+		(at 7.62 -9.76)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(thermal_bridge_angle 90)
+		(uuid "ff67e290-dcc2-4cf6-aa9e-52b47e7e2505")
+	)
+	(pad "12" thru_hole rect
+		(at 7.62 -7.22)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(uuid "9b4062d9-a81a-4feb-90ab-f52a4702dd22")
+	)
+	(pad "13" thru_hole circle
+		(at 7.62 -4.68)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(thermal_bridge_angle 90)
+		(uuid "57a0eb34-a60c-43db-ac5a-1ef89098cfe6")
+	)
+	(pad "20" thru_hole roundrect
+		(at -7.62 5.48)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "71f1a91c-3e50-4f7e-99f2-7c3a8d8d3b13")
+	)
+	(pad "21" thru_hole roundrect
+		(at -7.62 8.02)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "c1648a41-eada-4616-ba95-544c9aba37a1")
+	)
+	(zone
+		(layer "F.SilkS")
+		(uuid "cec382bf-3fc0-45d6-8c4b-2b379527a890")
+		(hatch edge 0.5)
+		(connect_pads
+			(clearance 0)
+		)
+		(min_thickness 0.25)
+		(keepout
+			(tracks allowed)
+			(vias allowed)
+			(pads not_allowed)
+			(copperpour allowed)
+			(footprints not_allowed)
+		)
+		(placement
+			(enabled no)
+			(sheetname "")
+		)
+		(fill
+			(thermal_gap 0.5)
+			(thermal_bridge_width 0.5)
+			(island_removal_mode 0)
+		)
+		(polygon
+			(pts
+				(xy -9 -11.5) (xy 9 -11.5) (xy 9 11.2) (xy -9 11.2)
+			)
+		)
+	)
+	(embedded_fonts no)
+)

esp_sensair_stuff.pretty/Sensair S8.kicad_mod

@@ -0,0 +1,560 @@
+(footprint "Sensair S8"
+	(version 20260206)
+	(generator "pcbnew")
+	(generator_version "10.0")
+	(layer "F.Cu")
+	(property "Reference" "REF**"
+		(at 0 -0.5 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "6a1aa33b-ac13-4328-ab4c-9a2837a7b786")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+		)
+	)
+	(property "Value" "Sensair S8"
+		(at 0 1 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(uuid "06cc6499-d79c-44e3-8373-4a7284908d8d")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(property "Datasheet" ""
+		(at 0 0 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(hide yes)
+		(uuid "a871e716-4118-4539-a990-70058f982170")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(property "Description" ""
+		(at 0 0 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(hide yes)
+		(uuid "312aa692-905e-4aee-9da3-b2040c9f122f")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(attr smd)
+	(duplicate_pad_numbers_are_jumpers no)
+	(fp_line
+		(start -16.07 -6.32)
+		(end -16.07 4.38)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "4e8aa03e-6790-4893-aada-93361e365177")
+	)
+	(fp_line
+		(start -16.07 4.38)
+		(end -13.1 4.38)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "b65618df-0040-40f4-9aa0-bc8b12ddc83e")
+	)
+	(fp_line
+		(start -14.1 -10.5)
+		(end 14.1 -10.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "dcd5cafb-a52b-4564-841b-de174ea93023")
+	)
+	(fp_line
+		(start -14.1 -6.3)
+		(end -14.1 -10.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "131dbcfd-316e-4547-9747-daa82335b740")
+	)
+	(fp_line
+		(start -14.1 10.5)
+		(end -14.1 4.35)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "a1582b3d-4850-4b2c-bbff-80654db3818f")
+	)
+	(fp_line
+		(start -13.1 -9.5)
+		(end -13.1 -6.32)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "e789a32b-a120-47e4-bdf7-82136e1b4332")
+	)
+	(fp_line
+		(start -13.1 -6.32)
+		(end -16.07 -6.32)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "e49eb3f6-7bc1-4532-ab9c-fda5100fbfef")
+	)
+	(fp_line
+		(start -13.1 4.38)
+		(end -13.1 9.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "92fbbe05-d739-47f2-ba98-b81d043b3913")
+	)
+	(fp_line
+		(start -13.1 9.5)
+		(end 13.1 9.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "3c21cf21-4ce1-452a-9ee0-85b2018ca42e")
+	)
+	(fp_line
+		(start 13.1 -9.5)
+		(end -13.1 -9.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "c87c5f56-a181-4aae-9062-efb5a43c7f78")
+	)
+	(fp_line
+		(start 13.1 -6.32)
+		(end 13.1 -9.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "b6e22611-1fdf-4210-9e25-ccf0dc7c8695")
+	)
+	(fp_line
+		(start 13.1 6.88)
+		(end 16.07 6.88)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "4a49cf34-3e04-4eb5-ab6c-3959b6522259")
+	)
+	(fp_line
+		(start 13.1 9.5)
+		(end 13.1 6.88)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "1cad9a7c-9f9e-4885-8112-4b1a8556a686")
+	)
+	(fp_line
+		(start 14.1 -10.5)
+		(end 14.1 -6.3)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "8adfc9f6-a472-457d-8a50-16adae10c890")
+	)
+	(fp_line
+		(start 14.1 -6.3)
+		(end 14.1 -6.35)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "b3fefa0f-a0ed-4efa-b1db-ed8887a94109")
+	)
+	(fp_line
+		(start 14.1 6.9)
+		(end 14.1 10.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "49e93a5f-19c8-4fcc-9949-0418c7289965")
+	)
+	(fp_line
+		(start 14.1 10.5)
+		(end -14.1 10.5)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "e4c489d9-f45f-4ebc-9f6e-ca2617467e16")
+	)
+	(fp_line
+		(start 16.07 -6.32)
+		(end 13.1 -6.32)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "bd80a5a2-fceb-4a52-a626-92ff21a55091")
+	)
+	(fp_line
+		(start 16.07 6.88)
+		(end 16.07 -6.32)
+		(stroke
+			(width 0.1)
+			(type default)
+		)
+		(layer "F.SilkS")
+		(uuid "b992e8a2-db19-41e3-b652-6e3abec9f8ff")
+	)
+	(fp_rect
+		(start -14.1 -10.5)
+		(end 14.1 10.5)
+		(stroke
+			(width 0.05)
+			(type default)
+		)
+		(fill no)
+		(layer "Edge.Cuts")
+		(uuid "928181a3-bbad-4131-88a8-f282e4de80be")
+	)
+	(fp_text user "5V"
+		(at -16.2 -4.1 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "402112dc-8b99-4674-a69b-f7ee80303a28")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify right bottom)
+		)
+	)
+	(fp_text user "GND"
+		(at -16.2 -1.6 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "442a69ea-290d-4fcb-8b60-b60ddad287c9")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify right bottom)
+		)
+	)
+	(fp_text user "Alarm_OC"
+		(at -16.2 1 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "cd75fd21-283e-4b07-8004-c0672209ae86")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify right bottom)
+		)
+	)
+	(fp_text user "PWM_1kHz"
+		(at -16.2 3.5 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "0f42750a-0f11-4bc3-b4fe-a7361bc59634")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify right bottom)
+		)
+	)
+	(fp_text user "DVCC_out"
+		(at 16.2 -4 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "f48ba3bd-c514-4fb0-a4e1-b445464469ea")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "UART_RxD"
+		(at 16.2 -1.62 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "a32492c1-a233-45a5-ae8f-9e5ccab89e27")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "UART_TxD"
+		(at 16.2 0.92 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "1435641f-cc62-49e4-8a04-fcae5288578e")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "UART_R/T"
+		(at 16.2 3.46 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "4132d630-c033-4590-bf83-16dae8ec71ad")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "bCal_in"
+		(at 16.2 6 0)
+		(unlocked yes)
+		(layer "F.SilkS")
+		(uuid "f27447c0-7e80-4763-88c3-54da18a9077e")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.1)
+			)
+			(justify left bottom)
+		)
+	)
+	(fp_text user "${REFERENCE}"
+		(at 0 2.5 0)
+		(unlocked yes)
+		(layer "F.Fab")
+		(uuid "0ae51aaa-ef31-441a-810e-76550cc6137a")
+		(effects
+			(font
+				(size 1 1)
+				(thickness 0.15)
+			)
+		)
+	)
+	(pad "0" thru_hole roundrect
+		(at -14.85 -4.78)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "d0a11e81-5ba6-4d93-8991-9392d7824a8a")
+	)
+	(pad "1" thru_hole roundrect
+		(at -14.85 -2.24)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "f138287e-1d7c-460f-8b13-47e58ea5b685")
+	)
+	(pad "2" thru_hole roundrect
+		(at -14.85 0.3)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "12a1e03d-e2d3-4e01-bdd9-9694f3192002")
+	)
+	(pad "3" thru_hole roundrect
+		(at -14.85 2.84)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "88ec7a17-e3bc-4f2a-ad7b-feb43dbb8b31")
+	)
+	(pad "4" thru_hole roundrect
+		(at 14.85 -4.78)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "4486bfdf-7a75-4a99-871a-3f8c382b2f0e")
+	)
+	(pad "5" thru_hole roundrect
+		(at 14.85 -2.24)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "da005d43-50b1-4d73-ba59-e733cef40f48")
+	)
+	(pad "6" thru_hole roundrect
+		(at 14.85 0.3)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "f739bcc0-1df7-41de-bf15-cc0f60922108")
+	)
+	(pad "7" thru_hole roundrect
+		(at 14.85 2.84)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "dc83bfdb-ed5f-4cd6-8258-e2805fb8c181")
+	)
+	(pad "8" thru_hole roundrect
+		(at 14.85 5.38)
+		(size 1.27 1.27)
+		(drill 0.8)
+		(layers "*.Cu" "*.Mask")
+		(remove_unused_layers no)
+		(roundrect_rratio 0.15)
+		(uuid "1f27dbad-eb78-4187-ac42-2491ece9b3ec")
+	)
+	(zone
+		(layer "F.SilkS")
+		(uuid "14708e9f-d985-43ab-a9ab-af419031a345")
+		(hatch edge 0.5)
+		(connect_pads
+			(clearance 0)
+		)
+		(min_thickness 0.25)
+		(keepout
+			(tracks allowed)
+			(vias allowed)
+			(pads not_allowed)
+			(copperpour allowed)
+			(footprints not_allowed)
+		)
+		(placement
+			(enabled no)
+			(sheetname "")
+		)
+		(fill
+			(thermal_gap 0.5)
+			(thermal_bridge_width 0.5)
+			(island_removal_mode 0)
+		)
+		(polygon
+			(pts
+				(xy -16.07 -6.32) (xy -13.1 -6.32) (xy -13.1 4.38) (xy -16.07 4.38)
+			)
+		)
+	)
+	(zone
+		(layer "F.SilkS")
+		(uuid "d16a9ebf-29d3-402a-8944-d267a36daa01")
+		(hatch edge 0.5)
+		(connect_pads
+			(clearance 0)
+		)
+		(min_thickness 0.25)
+		(keepout
+			(tracks allowed)
+			(vias allowed)
+			(pads not_allowed)
+			(copperpour allowed)
+			(footprints not_allowed)
+		)
+		(placement
+			(enabled no)
+			(sheetname "")
+		)
+		(fill
+			(thermal_gap 0.5)
+			(thermal_bridge_width 0.5)
+			(island_removal_mode 0)
+		)
+		(polygon
+			(pts
+				(xy -13.1 -9.5) (xy 13.1 -9.5) (xy 13.1 9.5) (xy -13.1 9.5)
+			)
+		)
+	)
+	(zone
+		(layer "F.SilkS")
+		(uuid "e276edeb-dee2-4a01-b436-51aa053efcf0")
+		(hatch edge 0.5)
+		(connect_pads
+			(clearance 0)
+		)
+		(min_thickness 0.25)
+		(keepout
+			(tracks allowed)
+			(vias allowed)
+			(pads not_allowed)
+			(copperpour allowed)
+			(footprints not_allowed)
+		)
+		(placement
+			(enabled no)
+			(sheetname "")
+		)
+		(fill
+			(thermal_gap 0.5)
+			(thermal_bridge_width 0.5)
+			(island_removal_mode 0)
+		)
+		(polygon
+			(pts
+				(xy 13.1 -6.32) (xy 16.07 -6.32) (xy 16.07 6.88) (xy 13.1 6.88)
+			)
+		)
+	)
+	(embedded_fonts no)
+)

firmware/README.md

@@ -0,0 +1,31 @@
+# Firmware
+
+ESPHome configuration for the ESP32-C3 CO₂ & environment sensor board.
+
+## Target
+
+| Item | Value |
+|---|---|
+| Chip | ESP32-C3 (RISC-V, single core, Wi-Fi + BLE) |
+| Framework | ESPHome (`esp32` platform, `framework: esp-idf` or `arduino`) |
+| Board | this project's board, flashed via the module's UART/USB boot pins |
+
+## Peripherals
+
+| Peripheral | Bus | Notes |
+|---|---|---|
+| Sensirion S8 (NDIR CO₂) | UART, 9600 baud 8N1 | needs 5 V supply, ~30 s preheat; `bCal_in` starts a manual background calibration |
+| BME280 (T / RH / P) | I²C, address `0x76` (some breakouts `0x77`) | powered from the module's 3.3 V output; pull-ups come from the breakout |
+| SW1 | GPIO, active low with 1 kΩ / 100 nF RC debounce | calibration button |
+
+## Add here
+
+- `esp-sensair.yaml` — the ESPHome configuration actually flashed to the board
+- `secrets.yaml` — **do not commit** (Wi-Fi credentials, Home Assistant token); keep
+  `secrets.yaml.example` with placeholders
+- flashing notes: `esptool` / `esphome flash`, boot-mode entry on the module
+
+## Home Assistant
+
+The device is exposed as native ESPHome entities: `co2`, `temperature`, `relative_humidity`,
+`pressure`, plus the calibration button as a sensor event.

fp-lib-table

@@ -0,0 +1,4 @@
+(fp_lib_table
+	(version 7)
+	(lib (name "esp_sensair_stuff") (type "KiCad") (uri "${KIPRJMOD}/esp_sensair_stuff.pretty") (options "") (descr ""))
+)

gerber/esp+sensair-B_Silkscreen.gbr

@@ -0,0 +1,15 @@
+G04 #@! TF.GenerationSoftware,KiCad,Pcbnew,10.0.6*
+G04 #@! TF.CreationDate,2026-09-08T00:42:25+02:00*
+G04 #@! TF.ProjectId,esp+sensair,6573702b-7365-46e7-9361-69722e6b6963,rev?*
+G04 #@! TF.SameCoordinates,Original*
+G04 #@! TF.FileFunction,Legend,Bot*
+G04 #@! TF.FilePolarity,Positive*
+%FSLAX46Y46*%
+G04 Gerber Fmt 4.6, Leading zero omitted, Abs format (unit mm)*
+G04 Created by KiCad (PCBNEW 10.0.6) date 2026-09-08 00:42:25*
+%MOMM*%
+%LPD*%
+G01*
+G04 APERTURE LIST*
+G04 APERTURE END LIST*
+M02*

gerber/esp+sensair-Edge_Cuts.gbr

@@ -0,0 +1,34 @@
+G04 #@! TF.GenerationSoftware,KiCad,Pcbnew,10.0.6*
+G04 #@! TF.CreationDate,2026-09-08T00:42:25+02:00*
+G04 #@! TF.ProjectId,esp+sensair,6573702b-7365-46e7-9361-69722e6b6963,rev?*
+G04 #@! TF.SameCoordinates,Original*
+G04 #@! TF.FileFunction,Profile,NP*
+%FSLAX46Y46*%
+G04 Gerber Fmt 4.6, Leading zero omitted, Abs format (unit mm)*
+G04 Created by KiCad (PCBNEW 10.0.6) date 2026-09-08 00:42:25*
+%MOMM*%
+%LPD*%
+G01*
+G04 APERTURE LIST*
+G04 #@! TA.AperFunction,Profile*
+%ADD10C,0.050000*%
+G04 #@! TD*
+G04 APERTURE END LIST*
+D10*
+X126300000Y-67000000D02*
+X99500000Y-67000000D01*
+X126300000Y-50500000D02*
+X126300000Y-67000000D01*
+X126300000Y-50500000D02*
+X138500000Y-50500000D01*
+X99500000Y-50500000D02*
+X99500000Y-67000000D01*
+X88500000Y-50500000D02*
+X99500000Y-50500000D01*
+X88500000Y-90500000D02*
+X88500000Y-50500000D01*
+X138500000Y-90500000D02*
+X88500000Y-90500000D01*
+X138500000Y-50500000D02*
+X138500000Y-90500000D01*
+M02*

gerber/esp+sensair-NPTH.drl

@@ -0,0 +1,6 @@
+M48
+INCH,TZ
+%
+G90
+G05
+M30

gerber/esp+sensair-PTH.drl

@@ -0,0 +1,51 @@
+M48
+INCH,TZ
+T1C0.0315
+T2C0.0394
+T3C0.0433
+%
+G90
+G05
+T1
+X35558Y-28343
+X35558Y-34343
+X36558Y-28343
+X36558Y-34343
+X37558Y-28343
+X37558Y-34343
+X38504Y-20520
+X38504Y-21520
+X38504Y-22520
+X38504Y-23520
+X38558Y-28343
+X38558Y-34343
+X39558Y-28343
+X39558Y-34343
+X40558Y-28343
+X40558Y-34343
+X41558Y-28343
+X41558Y-34343
+X42558Y-28343
+X42558Y-34343
+X44610Y-31563
+X44610Y-34563
+X50197Y-20520
+X50197Y-21520
+X50197Y-22520
+X50197Y-23520
+X50197Y-24520
+X50417Y-29587
+X50417Y-30587
+X50417Y-31587
+X50417Y-32587
+X50417Y-33587
+X50417Y-34587
+T2
+X45146Y-27953
+X45146Y-29921
+T3
+X50984Y-26280
+X50984Y-28051
+X53543Y-26280
+X53543Y-28051
+M30

gerber/esp+sensair-job.gbrjob

@@ -0,0 +1,147 @@
+{
+  "Header": {
+    "GenerationSoftware": {
+      "Vendor": "KiCad",
+      "Application": "Pcbnew",
+      "Version": "10.0.6"
+    },
+    "CreationDate": "2026-09-08T00:42:25+02:00"
+  },
+  "GeneralSpecs": {
+    "ProjectId": {
+      "Name": "esp+sensair",
+      "GUID": "6573702b-7365-46e7-9361-69722e6b6963",
+      "Revision": "rev?"
+    },
+    "Size": {
+      "X": 50.05,
+      "Y": 40.05
+    },
+    "LayerNumber": 4,
+    "BoardThickness": 1.6002,
+    "Finish": "None"
+  },
+  "DesignRules": [
+    {
+      "Layers": "Outer",
+      "PadToPad": 0.15,
+      "PadToTrack": 0.15,
+      "TrackToTrack": 0.15,
+      "MinLineWidth": 0.4,
+      "TrackToRegion": 0.5,
+      "RegionToRegion": 0.5
+    },
+    {
+      "Layers": "Inner",
+      "PadToPad": 0.15,
+      "PadToTrack": 0.15,
+      "TrackToTrack": 0.15
+    }
+  ],
+  "FilesAttributes": [
+    {
+      "Path": "esp+sensair-Front.gbr",
+      "FileFunction": "Copper,L1,Top",
+      "FilePolarity": "Positive"
+    },
+    {
+      "Path": "esp+sensair-Back.gbr",
+      "FileFunction": "Copper,L4,Bot",
+      "FilePolarity": "Positive"
+    },
+    {
+      "Path": "esp+sensair-F_Silkscreen.gbr",
+      "FileFunction": "Legend,Top",
+      "FilePolarity": "Positive"
+    },
+    {
+      "Path": "esp+sensair-B_Silkscreen.gbr",
+      "FileFunction": "Legend,Bot",
+      "FilePolarity": "Positive"
+    },
+    {
+      "Path": "esp+sensair-F_Mask.gbr",
+      "FileFunction": "SolderMask,Top",
+      "FilePolarity": "Negative"
+    },
+    {
+      "Path": "esp+sensair-B_Mask.gbr",
+      "FileFunction": "SolderMask,Bot",
+      "FilePolarity": "Negative"
+    },
+    {
+      "Path": "esp+sensair-Edge_Cuts.gbr",
+      "FileFunction": "Profile",
+      "FilePolarity": "Positive"
+    }
+  ],
+  "MaterialStackup": [
+    {
+      "Type": "Legend",
+      "Name": "Top Silk Screen"
+    },
+    {
+      "Type": "SolderPaste",
+      "Name": "Top Solder Paste"
+    },
+    {
+      "Type": "SolderMask",
+      "Thickness": 0.01,
+      "Name": "Top Solder Mask"
+    },
+    {
+      "Type": "Copper",
+      "Thickness": 0.035,
+      "Name": "Front"
+    },
+    {
+      "Type": "Dielectric",
+      "Thickness": 0.4801,
+      "Material": "FR4",
+      "Name": "Front/In1.Cu",
+      "Notes": "Type: dielectric layer 1 (from Front to In1.Cu)"
+    },
+    {
+      "Type": "Copper",
+      "Thickness": 0.035,
+      "Name": "In1.Cu"
+    },
+    {
+      "Type": "Dielectric",
+      "Thickness": 0.4801,
+      "Material": "FR4",
+      "Name": "In1.Cu/In2.Cu",
+      "Notes": "Type: dielectric layer 2 (from In1.Cu to In2.Cu)"
+    },
+    {
+      "Type": "Copper",
+      "Thickness": 0.035,
+      "Name": "In2.Cu"
+    },
+    {
+      "Type": "Dielectric",
+      "Thickness": 0.4801,
+      "Material": "FR4",
+      "Name": "In2.Cu/Back",
+      "Notes": "Type: dielectric layer 3 (from In2.Cu to Back)"
+    },
+    {
+      "Type": "Copper",
+      "Thickness": 0.035,
+      "Name": "Back"
+    },
+    {
+      "Type": "SolderMask",
+      "Thickness": 0.01,
+      "Name": "Bottom Solder Mask"
+    },
+    {
+      "Type": "SolderPaste",
+      "Name": "Bottom Solder Paste"
+    },
+    {
+      "Type": "Legend",
+      "Name": "Bottom Silk Screen"
+    }
+  ]
+}

photos/README.md

@@ -0,0 +1,13 @@
+Photographs of the assembled board.
+
+Suggested shots for the README (top-down, evenly lit, plain background, 1600 px wide):
+
+- `top.jpg`      assembled board, front side, all parts visible
+- `bottom.jpg`   solder side
+- `installed.jpg` board in its final location / enclosure
+- `running.jpg`  Home Assistant dashboard showing live values
+
+Add them to the README once taken:
+
+    ![Assembled board, top](photos/top.jpg)
+    ![Assembled board, bottom](photos/bottom.jpg)