Initial commit: ZNET Temperature Sensor ESP32 firmware

- PlatformIO project for Meshnology ESP32 LoRa V3 - DS18B20 dual sensor support for tank verification - OLED display for local temperature visibility - HTTP POST to ZNET Web API - WiFiManager for easy WiFi configuration - Offline buffering when network unavailable Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2026-01-24 16:48:12 -06:00
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+# ZNET Temperature Sensor - ESP32 LoRa Gateway
+
+## Project Overview
+
+ESP32-based temperature monitoring system for e-coat paint tanks. Reads DS18B20 waterproof temperature probes immersed in the paint tank and sends data to ZNET Web for real-time monitoring and ML feature collection.
+
+## Hardware
+
+| Component | Model | Purpose |
+|-----------|-------|---------|
+| MCU | Meshnology ESP32 LoRa V3 | Main controller with WiFi, LoRa, OLED |
+| Temp Sensor | DS18B20 (x2) | Waterproof stainless steel probes in paint tank |
+| Display | Built-in 0.96" OLED | Local temperature display for operators |
+| Radio | Built-in SX1262 | LoRa 915MHz for future remote sensors |
+
+## Quick Start
+
+### Build & Upload
+```bash
+# Install PlatformIO CLI
+pip install platformio
+
+# Build
+cd ~/Nextcloud/Dev/znet-temp-sensor
+pio run
+
+# Upload to ESP32 (connect via USB)
+pio run --target upload
+
+# Monitor serial output
+pio device monitor
+```
+
+### Configure WiFi
+1. Power on the ESP32
+2. Connect to WiFi network: `ZNET-TempSensor` (password: `znettemp123`)
+3. Browser opens captive portal - enter your WiFi credentials
+4. Device connects and starts posting to ZNET Web
+
+### Configure API Endpoint
+Edit `include/config.h`:
+```cpp
+#define ZNET_API_URL "http://192.168.1.100:8000/api/v1/sensors/readings"
+```
+
+## Wiring
+
+### DS18B20 Connection (1-Wire bus, both sensors on same pin)
+```
+ESP32 GPIO7 ─────┬───────────── DS18B20 #1 DATA (yellow)
+                 │
+                 └───────────── DS18B20 #2 DATA (yellow)
+
+ESP32 3.3V ──────┬───────────── DS18B20 #1 VCC (red)
+                 │
+                 └───────────── DS18B20 #2 VCC (red)
+
+ESP32 GND ───────┬───────────── DS18B20 #1 GND (black)
+                 │
+                 └───────────── DS18B20 #2 GND (black)
+
+4.7kΩ pullup resistor between DATA and VCC
+```
+
+### GPIO Pinout (Heltec V3 / Meshnology)
+| Function | GPIO |
+|----------|------|
+| OneWire Data | 7 |
+| OLED SDA | 17 |
+| OLED SCL | 18 |
+| OLED RST | 21 |
+| LoRa SCK | 9 |
+| LoRa MISO | 11 |
+| LoRa MOSI | 10 |
+| LoRa SS | 8 |
+| LoRa RST | 12 |
+| LoRa DIO1 | 14 |
+| LoRa BUSY | 13 |
+
+## Configuration
+
+All configuration in `include/config.h`:
+
+| Setting | Default | Description |
+|---------|---------|-------------|
+| `ZNET_API_URL` | - | ZNET Web API endpoint |
+| `DEVICE_ID` | `tank_gateway_1` | Unique device identifier |
+| `TEMP_READ_INTERVAL_MS` | 30000 | Reading interval (30 sec) |
+| `TEMP_MIN_VALID_F` | 32.0 | Minimum valid temperature |
+| `TEMP_MAX_VALID_F` | 150.0 | Maximum valid temperature |
+
+## API Integration
+
+### POST /api/v1/sensors/readings
+```json
+{
+  "device_id": "tank_gateway_1",
+  "device_name": "E-Coat Tank Gateway",
+  "readings": [
+    {
+      "sensor_id": "tank_primary",
+      "temperature_f": 85.5,
+      "is_valid": true
+    },
+    {
+      "sensor_id": "tank_secondary",
+      "temperature_f": 85.3,
+      "is_valid": true
+    }
+  ]
+}
+```
+
+### Response
+```json
+{
+  "success": true,
+  "readings_stored": 2,
+  "alerts_generated": 0
+}
+```
+
+## Features
+
+### Implemented
+- [x] Dual DS18B20 sensor reading with validation
+- [x] OLED display showing current temperature
+- [x] WiFiManager for easy WiFi setup
+- [x] HTTP POST to ZNET Web API
+- [x] Offline buffering when network unavailable
+- [x] Automatic sensor discovery (1-Wire)
+
+### Future (Phase 3)
+- [ ] LoRa receive for remote sensor nodes
+- [ ] Battery-powered remote node firmware
+- [ ] Sensor agreement monitoring
+- [ ] Flash storage for offline buffer persistence
+
+## Related Projects
+
+- **ZNET Web**: `~/Nextcloud/Dev/znet-web` - Backend receives temperature data
+- **Baserow**: Table for lab temperature logs (to be created)
+
+## Git Repository
+
+- **Remote:** https://git.ecoat.us/leehughes/znet-temp-sensor.git
+- **Main branch:** `main`
+
+## Change Log
+
+| Date | Version | Change |
+|------|---------|--------|
+| 2026-01-24 | 1.0.0 | Initial implementation |