Hannes
ac5a556c11
- firmware/: config + secrets templates committed, flashed config git-ignored - README: document the GND pour on F.Cu/B.Cu and the module keep-out rule areas - README: correct the calibration button wiring (S8 bCal_in, not an MCU GPIO) - README: v2 list - dedicated 5 V power input, decoupling, mounting holes, I2C pull-ups, schematic annotation, RoHS finish, project name, antenna keep-out
60 lines
2.1 KiB
Markdown
60 lines
2.1 KiB
Markdown
# Firmware
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ESPHome firmware for the ESP32-C3 CO₂ & environment sensor board.
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## Files
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| File | In git | Purpose |
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| `esp-sensair.yaml.example` | yes | configuration template, all credentials as `!secret` references |
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| `secrets.yaml.example` | yes | secrets template with placeholders |
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| `esp-sensair.yaml` | **no** (git-ignored) | your flashed configuration |
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| `secrets.yaml` | **no** (git-ignored) | your Wi-Fi, API, OTA and hotspot credentials |
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Setup:
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```bash
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cp firmware/esp-sensair.yaml.example firmware/esp-sensair.yaml
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cp firmware/secrets.yaml.example firmware/secrets.yaml
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# fill in firmware/secrets.yaml
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esphome run firmware/esp-sensair.yaml
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```
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Generate the Home Assistant API encryption key with:
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```bash
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python3 -c "import base64,os; print(base64.b64encode(os.urandom(32)).decode())"
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```
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## Target
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| Item | Value |
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| Chip | ESP32-C3 (RISC-V, single core, Wi-Fi) |
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| ESPHome board | `esp32-c3-devkitm-1` |
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| Framework | ESP-IDF |
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| Flashing | USB-C on the devkit module (ESPHome OTA after first flash) |
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## Peripherals
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| Peripheral | Bus | Pins | Notes |
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| Sensirion S8 (NDIR CO₂) | UART, 9600 baud 8N1 | `TX = GPIO21`, `RX = GPIO20` | 5 V supply, ~30 s preheat; the S8's own `bCal_in` pin carries the on-board calibration button |
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| BME280 (T / RH / P) | I²C, address `0x76` | `SDA = GPIO7`, `SCL = GPIO8` | powered from the module's 3.3 V output, pull-ups on the breakout |
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| SW1 | — | not on the MCU | wired to the S8 `bCal_in` input with a 1 kΩ / 100 nF RC network |
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Update interval for both sensors: 60 s.
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## Home Assistant
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Exposed as native ESPHome entities: CO₂, temperature, relative humidity, pressure. API connection is
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encrypted (noise protocol), OTA updates enabled, static IP with a fallback hotspot and captive portal
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if the Wi-Fi connection fails.
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## Ideas for v2
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- Trigger the S8 background calibration from Home Assistant (`senseair` platform actions) in addition
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to the hardware button, and log the calibration events.
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- Automatic baseline calibration window tuned to the room's nightly CO₂ minimum.
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- Report Wi-Fi signal strength and device uptime as sensors for diagnostics.
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