znet-temp-sensor/CLAUDE.md

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

# 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:

#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

{
  "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

{
  "success": true,
  "readings_stored": 2,
  "alerts_generated": 0
}

Features

Implemented

• Dual DS18B20 sensor reading with validation
• OLED display showing current temperature
• WiFiManager for easy WiFi setup
• HTTP POST to ZNET Web API
• Offline buffering when network unavailable
• 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