ESP32 Pump Monitor

A lightweight ESP32-based pump monitoring system using an AC current switch (e.g. SZC23-NO-AL-CH).

The device detects pump activity, records pump cycles, aggregates statistics, and exposes metrics via a simple HTTP JSON API.

Features

• Detect pump activity via digital GPIO input
• Poll sensor periodically (default: 500 ms)
• Debounce state transitions
• Record completed pump cycles
• Synchronize time via NTP
• Provide rolling statistics for:
  • last 24 hours
  • last 7 days
  • last 30 days
  • lifetime
• Expose metrics via HTTP/JSON
• Designed for integration with external monitoring systems such as Icinga2

No web UI, authentication, or embedded alerting is implemented.

Pump Cycle Definition

A pump cycle consists of:

• start timestamp
• end timestamp
• idle time since previous cycle

Idle time is defined as:

next_cycle_start - previous_cycle_end

Metrics

Current State

{
  "running": true,
  "current_cycle_duration": 512,
  "time_since_last_cycle": 18234
}

Rolling Statistics

For each interval (24h, 7d, 30d, lifetime):

{
  "count": 17,
  "runtime_total": 812,
  "duration_min": 22,
  "duration_max": 91,
  "duration_avg": 47,
  "gap_min": 180,
  "gap_max": 8200,
  "gap_avg": 2400
}

HTTP API

GET /metrics

Returns current state and aggregated statistics as JSON.

Storage

Completed pump cycles are stored persistently as append-only event records.

Statistics may be recomputed from recorded events after reboot.

Intended Use

The monitor is intended to:

• observe pump behavior
• provide operational statistics
• support external monitoring and alerting

Alert thresholds and notifications should be implemented externally (e.g. in Icinga2).