# 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 |